Enhanced Luminol Chemiluminescence with Oxidase-like Activity of NiOOH/Ni(OH)2 Nanoflakes for the Sensitive Detection of Mn2+

Enhanced Luminol Chemiluminescence with Oxidase-like Activity of NiOOH/Ni(OH)2 Nanoflakes for the Sensitive Detection of Mn2+ | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Enhanced Luminol Chemiluminescence with Oxidase-like Activity of NiOOH/Ni(OH) 2 Nanoflakes for the Sensitive Detection of Mn 2+ Jiaqian Qi, Yang Chen, Jing Chen, Funan Chen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6520640/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Jun, 2025 Read the published version in Microchimica Acta → Version 1 posted 13 You are reading this latest preprint version Abstract Nickel hydroxide nanoflakes incorporating amorphous nickel oxyhydroxide (NiOOH/Ni(OH) 2 NFs) were synthesized through a chemical oxidation approach. NiOOH/Ni(OH) 2 NFs maintains the two-dimensional structure of Ni(OH) 2 nanoflakes with an enlarged specific surface area. Furthermore, the amorphous NiOOH possesses abundant high-valence nickel active sites, endowing the material with remarkable oxidase-like activity. This catalytic property enabled the generation of reactive oxygen species (ROS) from dissolved oxygen, enhancing the luminol chemiluminescence (CL) intensity by over 2,000-fold without requiring external oxidants. Mn 2+ significantly quenched the CL signal by scavenging ROS, enabling a linear detection range of 1‒30 μmol·L −1 and a detection limit of 0.60 μmol·L −1 , which is 3-fold lower than the World Health Organization (WHO) permissible limit (1.80 μmol·L −1 ) for drinking water. The sensor was successfully applied to tap and lake water samples, demonstrating simplicity, rapid response, and high selectivity, making it a promising method for environmental monitoring. chemiluminescence luminol nickel oxyhydroxides oxidase-like Mn2+ Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Chemiluminescence (CL) is a phenomenon in which electronically excited species generated during a chemical reaction return to their ground state, releasing energy in the form of light radiation [ 1 ]. Due to its advantages such as high sensitivity, broad linear range, requiring no external light source, as well as its simple instrumentation, ease of operation, and rapid analysis speed, CL analysis has become a powerful trace analysis technique [ 2 , 3 ]. It finds extensive applications in fields such as environmental monitoring [ 4 ], biomedical and clinical testing [ 5 ], and food safety [ 6 ]. Since the chemiluminescent properties of luminol under alkaline conditions were first documented by Albrecht in 1928 [ 7 ], luminol has become one of the most common CL reagents due to its advantages such as simple structure, good water solubility, and low cost. It can generate CL when combined with some common oxidants such as hydrogen peroxide, potassium permanganate, and hypochlorite [ 8 ]. Conventional luminol-based systems are inherently limited by chemical instability and low luminescence efficiency [ 9 , 10 ]. This requires the development of novel luminol CL systems that operate without external oxidants to overcome these limitations. Metal oxyhydroxides demonstrate remarkable catalytic activity owing to their high-valent metal active sites and the charge transfer capability among varying valence states [ 11 , 12 ]. Specifically, nickel oxyhydroxides (NiOOH) exhibit superior surface reactivity and electrocatalytic activity, along with non-toxicity, unique structure and biocompatibility, which have been widely applied in urea oxidation reactions[ 13 ] and alkaline water electrolysis[ 14 ]. However, current research has primarily focused on the electrocatalytic properties of NiOOH, while its potential in optical biosensing remains largely unexplored. Notably, other metal oxyhydroxides have shown exceptional performance in oxidant-free optical detection systems, FeOOH nanorods [ 15 ] enabled luminol CL-based ultrasensitive detection of uric acid, CoOOH nanosheets [ 16 ] directly oxidized luminol for glutathione sensing. These studies clearly demonstrate the enzyme-like catalytic potential of metal oxyhydroxides. Building upon these findings, we systematically investigated the oxidase-like activity of NiOOH and developed a novel oxidant-free luminol chemiluminescence system, thereby expanding the application frontiers of NiOOH in optical biosensing. Manganese ions (Mn 2+ ) serve as crucial trace elements in human physiology, playing essential roles in numerous enzymatic processes and metabolic pathways [ 17 ]. Chronic exposure to excessive Mn²⁺ levels may trigger irreversible Parkinsonian-like neurodegeneration, while occupational or environmental exposure can lead to cognitive impairment and motor coordination deficits [ 18 – 20 ]. Therefore, precise quantification of Mn 2+ concentrations in both tap water and environmental water samples carries significant analytical importance. Extensive research efforts have been devoted to developing analytical techniques for Mn 2+ detection in aqueous solutions, primarily including inductively coupled plasma techniques (ICP) [ 21 ], atomic absorption spectroscopy (AAS) [ 22 ], spectrophotometry [ 23 ], electrochemical sensor [ 24 ], fluorescence spectroscopy [ 25 ], and so on. Although these methods exhibit good sensitivity for Mn 2+ detection, they still present certain limitations. For instance, AAS and ICP-MS require lengthy sample pretreatment and instrument calibration, along with expensive equipment and complex operations, Spectrophotometry and fluorometry rely on external light sources and may be interfered with by sample matrices and impurities [ 26 ]. In contrast, CL detection offers distinct advantages for Mn²⁺ monitoring, including operational simplicity without requiring external light sources and rapid response times (< 1 minute). These characteristics position CL as a particularly promising technique for Mn²⁺ detection. In this work, Ni(OH) 2 nanoflakes incorporating amorphous NiOOH (NiOOH/Ni(OH) 2 NFs) was synthesized through a chemical oxidation method. The material preserved the two-dimensional structure of Ni(OH) 2 nanoflakes with a large specific surface area, while the incorporated amorphous NiOOH exhibited inherent flexibility and abundant active sites [ 27 , 28 ]. we discovered that NiOOH/Ni(OH) 2 NFs can dramatically enhance the CL intensity of luminol in an oxidant-free system. This enhancement originates from their intrinsic oxidase-like activity, which catalyzes the generation of reactive oxygen species (ROS) from dissolved oxygen, these ROS subsequently react with luminol anions to produce intense CL emission. Significant CL quenching was observed upon Mn 2+ addition, indicating high selectivity and sensitivity toward Mn 2+ detection. Utilizing this phenomenon, we constructed a novel CL sensor for Mn 2+ detection in water samples, which offers rapid analysis and simple operation. 2. Experimental 2.1. Synthesis of NiOOH/Ni(OH)₂ NFs The synthesis of Ni(OH)₂ nanoflakes was performed according to the reported procedure [ 29 ]. 0.9 g of NiSO 4 ·6H 2 O was dissolved in 60 mL deionized water with constant stirring for 30 min at ambient temperature. Subsequently, 15 mL of NaOH solution (1 mol·L − 1 ) was added, and the mixture was stirred for an additional 30 minutes. The solution was transferred to a 100 mL autoclave and heated at 200°C for 12 hours. The resulting product was collected by centrifugation, washed repeatedly with deionized water, and dried under vacuum at 60°C overnight, obtaining a pale green powder. For the preparation of NiOOH/Ni(OH) 2 NFs, 0.25 g of Ni(OH) 2 and 0.6 g of NaOH were added to 10 mL K 2 S 2 O 8 solution (5 mg·L − 1 ). The mixture was stirred at 200 rpm for 3 hours, followed by centrifugation to collect the precipitate. The obtained precipitate was washed three times with deionized water and then dried overnight at 60°C to yield a black powder. 2.2. CL analysis program The flow injection chemiluminescence (FI-CL) analysis system, schematically illustrated in Fig. S1 . The system configuration consists of two peristaltic pumps and a photomultiplier tube (PMT), connected by PTFE tubing with dimensions of 1 mm (inner diameter) and 3 mm (outer diameter). In the experiment, 1000 µL of NiOOH/Ni(OH) 2 NFs was mixed with 500 µL of Mn 2+ solutions at varying concentrations. The mixture was injected into the system using pump P1, while pump P2 delivered the alkaline luminol solution (containing NaOH). Both solutions were transported through PTFE tubing to the reaction cell, where CL emission was detected. The light signals were amplified by the PMT and subsequently recorded using BPCL software on a Windows XP system 2.3. Detection of Mn 2+ in water samples Untreated tap water samples were directly used to assess the sensor performance. Lake water samples were settled for 12 hours to sediment silt, followed by filtration using a syringe equipped with a 0.22 µm membrane filter. Working solutions were prepared by combining 1000 µL NiOOH/Ni(OH) 2 NFs with 500 µL water samples spiked with Mn 2+ (5, 15, 25 µmol·L − 1 ). 3. Results and discussion 3.1 Characterization of NiOOH/Ni(OH) 2 NFs The XRD pattern in Fig. 1 a shows characteristic peaks at 19.0 °, 33.1 °, 38.5 °, and 52.1 °, corresponding to the (001), (100), (101), and (102) crystallographic planes of β-Ni(OH) 2 (JCPDS 14–0117), respectively. The weaker broad diffraction peaks at 37.3 ° and 66.6 ° are attributed to amorphous NiOOH [ 30 ]. From the TEM images (Fig S2), horizontally or vertically oriented hexagonal nanosheets can be observed. The HRTEM images (Fig. 1 b) demonstrate the lattice spacings of 0.272 nm and 0.459 nm for the (100) and (001) planes of Ni(OH) 2 [ 31 ]. The absence of distinct lattice fringes in the region marked by the blue squares further confirms the formation of amorphous NiOOH [ 32 ], consistent with the XRD results. The above analysis demonstrates the successful synthesis of Ni(OH) 2 nanosheets incorporating amorphous NiOOH. The surface functional groups of NiOOH/Ni(OH) 2 NFs were analyzed using FT-IR spectroscopy. Figure 1 c showed a characteristic peak at 3635 cm − 1 , corresponding to the free O-H stretching vibration. The broad band at 3450 cm − 1 was assigned hydrogen-bonded O-H stretching vibrations from hydroxyl groups and water molecules. Additionally, the band at 1631 cm − 1 was attributed to the bending vibration of water molecules, confirming the presence of surface-adsorbed water on the NiOOH/Ni(OH) 2 NFs [ 33 ]. The low-frequency band at approximately 1379 cm − 1 can be ascribed to the vibration of carbonate ions, resulting from CO 2 adsorption in the open synthesis environment. Additionally, the strong and sharp band centered at 524 cm − 1 was associated with the Ni-O-H bending vibrations and Ni 3+ -O stretching vibrations [ 34 ]. The elemental composition and chemical states of NiOOH/Ni(OH) 2 NFs were further investigated by XPS. The survey spectrum (Fig. S3) confirms the presence of Ni and O elements. In the high-resolution Ni 2p spectrum (Fig. 1 d), two spin-orbit doublets were observed, corresponding to Ni 2p 3/2 and Ni 2p 1/2 . The peaks at 856.4 and 874.2 eV were assigned to Ni 3+ , whereas those at 855.3 eV and 872.8 eV are attributed to Ni 2+ . The observed binding energies and peak separation were characteristic of mixed-valence nickel compounds [ 35 , 36 ]. The high-resolution O 1s XPS spectrum (Fig. 1 e) can be deconvoluted into three distinct components, representing different oxygen chemical environments: the peak at 529.3 eV was attributed to Ni-O bonds, 530.9 eV to O-H groups, and 532.2 eV to adsorbed water or oxygen species. [ 37 ]. 3.2 Oxidase-like activity of NiOOH/Ni(OH) 2 NFs The oxidase-like activity of NiOOH/Ni(OH) 2 NFs was examined using TMB as the substrate, and the formation of oxidized TMB (oxTMB) was tracked by UV-Vis spectroscopy. As shown in Fig. S4, no significant absorption peaks were observed in the visible range when TMB or NiOOH/Ni(OH) 2 NFs were tested individually. However, upon the addition of NiOOH/Ni(OH) 2 NFs to the TMB solution, the solution rapidly changed from colorless to blue (inset in the upper right corner of the Fig. S4), and a peak at 650 nm assigned to oxTMB was observed [ 38 , 39 ]. Furthermore, no oxTMB formation was detected when Ni(OH) 2 or Ni 2+ was added to TMB. These results demonstrate that NiOOH/Ni(OH) 2 NFs exhibits excellent oxidase-like activity. 3.3 Catalytic activity of NiOOH/Ni(OH) 2 NFs for luminol CL system The CL kinetics of the luminol- NiOOH/Ni(OH) 2 NFs system were obtained using the FL-CL system. As shown in Fig. 2 a, the alkaline luminol solution alone produces minimal CL, and Ni(OH) 2 does not enhance the CL signal. However, the addition of NiOOH/Ni(OH) 2 NFs results in a dramatic CL enhancement, approximately 2,000 times stronger than alkaline luminol alone, demonstrating the excellent catalytic activity of NiOOH/Ni(OH) 2 NFs in the luminol CL system. The enhanced catalytic activity is likely due to the high specific surface area and abundant active sites provided by the two-dimensional NiOOH/Ni(OH) 2 NFs structure. Key experimental parameters, including luminol concentration, NaOH concentration, NiOOH/Ni(OH) 2 NFs concentration, and flow rate, were optimized to achieve optimal catalytic performance. Based on the optimization results shown in Fig. S5, the following conditions were selected for subsequent experiments: 0.6 mmol·L − 1 luminol, 0.02 mol·L − 1 NaOH, 30 µg·mL − 1 NiOOH/Ni(OH) 2 NFs, and a flow rate of 2.00 mL·min − 1 . To elucidate the chemiluminescent species generated in the luminol-NiOOH/Ni(OH) 2 NFs system, the CL emission spectrum was acquired using a fluorescence spectrophotometer operated in CL mode (xenon lamp off). As depicted in Fig. 2 b, the system exhibits a characteristic emission maximum at 425 nm, which corresponds precisely to the known luminescence of the excited-state 3-aminophthalate anion (3-APA*), the oxidation product of luminol. This spectral evidence confirms that the CL mechanism involves the formation of 3-APA* through the catalytic oxidation of luminol by NiOOH/Ni(OH) 2 NFs [ 40 , 41 ]. Additionally, the UV-Vis absorption spectrum of NiOOH/Ni(OH) 2 NFs after the CL reaction was studied. As illustrated in the Fig. 2 c, compared to the individual NiOOH/Ni(OH) 2 NFs and luminol systems, the maximum absorption position of the luminol- NiOOH/Ni(OH) 2 NFs system shows no change, indicating that the addition of NiOOH/Ni(OH) 2 NFs does not generate new species [ 15 , 16 , 42 ]. This further confirms that NiOOH/Ni(OH) 2 NFs acts solely as a catalyst in the system. 3.4 CL mechanism of luminol with NiOOH/Ni(OH) 2 NFs systems The system operated without exogenous oxidants. To verify dissolved oxygen as the reactive oxygen species (ROS) source for the luminol CL reaction catalyzed by NiOOH/Ni(OH) 2 NFs, all test reagents were purged with N 2 /O 2 (30 min), while control reagents were exposed to ambient air under identical conditions. As shown in the Fig. 3a, the CL intensity of the luminol-NiOOH/Ni(OH) 2 NFs system decreased by approximately 50% under N 2 -saturated conditions, while it increased by about 30% under O 2 -saturated conditions, compared to ambient conditions. These results clearly demonstrate the crucial role of dissolved oxygen in the CL reaction. To identify the specific ROS involved in the luminol-NiOOH/Ni(OH) 2 NFs CL system, a series of radical scavenging experiments were systematically conducted. Three well-established scavengers were employed: thiourea(TH) for hydroxyl radicals (·OH), benzoquinone (BQ) for superoxide anions (·O − 2), and sodium azide (NaN 3 ) for singlet oxygen ( 1 O 2 ) [ 43 ]. As shown in Fig. 3b, in the luminol- NiOOH/Ni(OH) 2 NFs system, both BQ and TH significantly reduced the CL intensity, while NaN 3 had a negligible effect on the CL. This indicates that ·OH and ·O − 2 are the primary ROS involved in the CL emission process. To obtain unambiguous evidence of radical generation, electron spin resonance (ESR) spectroscopy was employed using 5,5′-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trapping agent. As shown in Fig. S6, characteristic signals of DMPO/·OH and DMPO/·O − 2 adducts were observed, providing direct evidence for the generation of both ·OH and ·O − 2 radicals during the CL reaction. Based on the experimental results, we propose a reaction mechanism for the luminol-NiOOH/Ni(OH) 2 NFs CL system (Scheme 1). The NiOOH/Ni(OH) 2 NFs catalyze the generation of ·O− 2 and ·OH from dissolved oxygen due to their oxidase-like activity. These ROS then oxidize luminol anion to form excited-state 3-APA*, which emits light at 425 nm when returning to its ground state. 3.5 Detection of Mn 2+ Leveraging the reducing properties of Mn 2+ , which effectively scavenges ROS and radicals generated in the system, we developed a highly sensitive CL sensor based on the luminol-NiOOH/Ni(OH) 2 NFs platform for direct Mn 2+ detection. Under optimized experimental conditions, the CL intensity exhibited a concentration-dependent decrease with increasing Mn 2+ levels, as shown in Fig. 4 a. Quantitative analysis revealed an excellent linear relationship between ( I ₀ − I )/ I ₀ and Mn 2+ concentration (Fig. 4 b), described by the equation ( I ₀ − I )/ I ₀ = 3.02 C Mn²⁺ + 3.71 ( R ² = 0.9977, n = 7), where I ₀ and I represent the CL intensities in the absence and presence of Mn 2+ , respectively. The linear dynamic range spanned from 1.00 to 30.00 µmol·L − 1 , with a limit of detection (LOD) of 0.60 µmol·L − 1 (3σ/k). The analytical precision of the Mn 2+ detection system was evaluated through 11 replicate measurements of a 5 µmol·L − 1 Mn 2+ standard solution, yielding a relative standard deviation (RSD) of 3.42%, which demonstrates exceptional method reproducibility. The developed sensor meets the detection requirement of the World Health Organization (WHO) drinking water standard of 1.80 µmol·L − 1 for Mn 2+ and exhibits superior sensitivity with a lower detection limit compared to existing methods, as detailed in Table S1 . Furthermore, the sensor offers significant advantages in terms of rapid response time and operational simplicity, requiring no complex sample pretreatment. To evaluate the practical applicability of the luminol-NiOOH/Ni(OH) 2 NFs sensor, we assessed potential interference from common coexisting ions in real water samples, including K + , Na + , Ag + , Ca 2+ , Ba 2+ , Zn 2+ , Cr 2+ , Hg 2+ , Pb 2+ , Cd 2+ , and Fe 3+ at 300 µmol·L − 1 . As illustrated in Fig. 4 c, the CL intensity significantly decreased upon the addition of 30 µmol·L − 1 Mn 2+ , while other ions showed negligible interference. These results confirmed the high specificity of the sensor for Mn 2+ detection, suggesting its suitability for analyzing real environmental water samples. The sensor was further applied to detect Mn 2+ in tap water and treated lake water samples. Spike recovery experiments were conducted to validate its practicality. As summarized in the Table S2, recoveries ranged from 96.92–102.86% for Mn 2+ spiked at 5 µmol·L − 1 , 15 µmol·L − 1 , and 25 µmol·L − 1 in tap water and lake water, with RSD values between 1.32% and 3.58% (n = 3). These results demonstrate the reliability and promising potential of this method for efficient Mn²⁺ determination in real water samples. 4. Conclusion In summary, we have proposed a novel luminol CL system induced by NiOOH/Ni(OH) 2 NFs without the addition of oxidants. The enhancement of luminescence is attributed to the excellent oxidase-like activity of NiOOH/Ni(OH) 2 NFs, which can decompose dissolved oxygen to generate various ROS such as ·OH and ·O − 2, leading to the enhancement of CL. Due to the significant inhibitory effect of Mn 2+ on the CL intensity of the luminol-NiOOH/Ni(OH) 2 NFs system, a simple, rapid, and sensitive method for detecting Mn 2+ has been developed. This study reveals that NiOOH/Ni(OH) 2 NFs is an efficient catalyst for the luminol chemiluminescence reaction, showcasing great potential for applications in the field of chemiluminescence. Statements and Declarations Competing Interest: We declare that we have no known competing financial interests or personal relationships that could have influenced the work reported in this paper. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Ethical Approval: Our study did not involve human participants, animals, or any ethical issues requiring approval. Author Contributions: All authors contributed to the study conception, design, and manuscript preparation. We approved the final version for submission. References Yang M, Huang J, Fan J, et al (2020) Chemiluminescence for bioimaging and therapeutics: recent advances and challenges. Chem Soc Rev 49:6800–6815. https://doi.org/10.1039/D0CS00348D Li S, Jiang Y, Huang R, Zhang X (2024) DNA-mediated chemiluminescence bioassays. TrAC Trends Anal Chem 175:117720. https://doi.org/10.1016/j.trac.2024.117720 David M, Gutkin S, Nithun RV, et al (2025) Unprecedented Photoinduced-Electron-Transfer Probe with a Turn-ON Chemiluminescence Mode-of-Action. Angew Chem Int Ed 64:e202417924. https://doi.org/10.1002/anie.202417924 Gou J, Qin Y, Tang W, et al (2025) Phosphorus nitride dot-activated ferrate (VI) with enhanced singlet oxygen mediating chemiluminescence for pyroquilon determination. Chem Eng J 505:159477. https://doi.org/10.1016/j.cej.2025.159477 Liu J, Huang J, Wei X, et al (2024) Near-Infrared Chemiluminescence Imaging of Chemotherapy-Induced Peripheral Neuropathy. Adv Mater 36:2310605. https://doi.org/10.1002/adma.202310605 Mao F, Yang X, He Z, et al (2025) Mimotope peptides for nanobodies: A nontoxic alternative to ochratoxin A and its application in chemiluminescence immunoassays for analysis of pepper samples. Food Chem 465:142061. https://doi.org/10.1016/j.foodchem.2024.142061 Albrecht HO (1928) Über die Chemiluminescenz des Aminophthalsäurehydrazids. Z Für Phys Chem 136U:321–330. https://doi.org/10.1515/zpch-1928-13625 Dong Z, Du F, Hanif S, et al (2024) Development of chemiluminescent systems and devices for analytical applications. Chem Commun 60:11837–11848. https://doi.org/10.1039/D4CC04414B Jiang Y, Yang X, Li S, et al (2024) Chemiluminescence initiated by nebulization of oxidant- and catalyst-free aqueous luminol solutions. Chem Eng J 481:148753. https://doi.org/10.1016/ j.cej.2024.148753 Deepa S, Venkatesan R, Jayalakshmi S, et al (2023) Recent advances in catalyst-enhanced luminol chemiluminescence system and its environmental and chemical applications. J Environ Chem Eng 11:109853. https://doi.org/10.1016/j.jece.2023.109853 Xu L, Li M, Zhao F, et al (2024) Low oxidation state engineering in transition metal-based interfacial regulation layer accelerates charge transfer kinetics toward enhanced photoelectrochemical water splitting. Appl Catal B Environ Energy 359:124503. https://doi.org/10.1016/j.apcatb.2024.124503 Theerthagiri J, Karuppasamy K, Justin Raj C, et al (2024) Structural engineering of metal oxyhydroxide for electrochemical energy conversion and storage. Coord Chem Rev 513:215880. https://doi.org/10.1016/j.ccr.2024.215880 Li X, Ma S, Tu L, et al (2025) Efficient urea removal with hydroperoxide production in bipolar membrane electrochemical cell using MoNiOOH nanoarray anode electrocatalyst. Appl Catal B Environ Energy 370:125158. https://doi.org/10.1016/j.apcatb.2025.125158 Shi F, Xiao L, Zhou Z, et al Accelerating the Transformation of Active β-NiOOH on NiFe Layered Double Hydroxide via Cation–anion Collaborative Coordination for Alkaline Water Oxidation at High Current Densities. Adv Funct Mater n/a:2501070. https://doi.org/10.1002/adfm.202501070 Ji K, Xia S, Sang X, et al (2023) Enhanced Luminol Chemiluminescence with Oxidase-like Properties of FeOOH Nanorods for the Sensitive Detection of Uric Acid. Anal Chem 95:3267–3273. https://doi.org/10.1021/acs.analchem.2c04247 Yang XJ, Li RS, Li CM, et al (2020) Cobalt oxyhydroxide nanoflakes with oxidase-mimicking activity induced chemiluminescence of luminol for glutathione detection. Talanta 215:120928. https://doi.org/10.1016/j.talanta.2020.120928 Obeng SK, Kulhánek M, Balík J, et al (2024) Manganese: From Soil to Human Health—A Comprehensive Overview of Its Biological and Environmental Significance. Nutrients 16:3455. https://doi.org/10.3390/nu16203455 Markiv B, Expósito A, Ruiz-Azcona L, et al (2023) Environmental exposure to manganese and health risk assessment from personal sampling near an industrial source of airborne manganese. Environ Res 224:115478. https://doi.org/10.1016/j.envres.2023.115478 Horning KJ, Caito SW, Tipps KG, et al (2015) Manganese Is Essential for Neuronal Health. Annu Rev Nutr 35:71–108. https://doi.org/10.1146/annurev-nutr-071714-034419 Ramachandran M, Schwabe KA, Ying SC (2021) Shallow Groundwater Manganese Merits Deeper Consideration. Environ Sci Technol 55:3465–3466. https://doi.org/10.1021/acs.est.0c08065 Alkas FB, Shaban JA, Sukuroglu AA, et al (2017) Monitoring and assessment of heavy metal/metalloid concentration by inductively coupled plasma mass spectroscopy (ICP-MS) method in Gonyeli Lake, Cyprus. Environ Monit Assess 189:516. https://doi.org/10.1007/s10661-017-6222-x Shilina Y, Ziv B, Meir A, et al (2016) Combined Electron Paramagnetic Resonance and Atomic Absorption Spectroscopy/Inductively Coupled Plasma Analysis As Diagnostics for Soluble Manganese Species from Mn-Based Positive Electrode Materials in Li-ion Cells. Anal Chem 88:4440–4447. https://doi.org/10.1021/acs.analchem.6b00204 Xu Y, Xu F, Liu Y, et al (2025) The clean analysis process of Mn 2+ for industries: a comparative study on direct determination of high-concentration Mn 2+ in solution using spectrophotometry. BMC Chem 19:21. https://doi.org/10.1186/s13065-024-01367-0 Boselli E, Wu Z, Friedman A, et al (2021) Validation of Electrochemical Sensor for Determination of Manganese in Drinking Water. Environ Sci Technol 55:7501–7509. https://doi.org/10.1021/ acs.est.0c05929 Yang L, Huang K, Li X, et al (2024) Fluorescence switching sensor for sensitive detection of curcumin/Mn 2+ using biomass carbon quantum dots: A combination of experimental and theoretical insights. J Environ Chem Eng 12:114533. https://doi.org/10.1016/j.jece.2024.114533 Alosaimi EH Recent Developments in Colorimetric and Fluorimetric Chemosensors for the Detection of Mn 2+ Ions: A Review (2010–2024). Crit Rev Anal Chem 0:1–21. https://doi.org/ 10.1080/10408347.2025.2460091 Zhang H, He X, Dong K, et al (2023) Selenate promoted stability improvement of nickel selenide nanosheet array with an amorphous NiOOH layer for seawater oxidation. Mater Today Phys 38:101249. https://doi.org/10.1016/j.mtphys.2023.101249 Wang T, Li X, Pang Y, et al (2021) Unlocking the synergy of interface and oxygen vacancy by core-shell nickel phosphide@oxyhydroxide nanosheets arrays for accelerating alkaline oxygen evolution kinetics. Chem Eng J 425:131491. https://doi.org/10.1016/j.cej.2021.131491 Kim N, Lim D, Choi Y, et al (2019) Hexagonal β-Ni(OH) 2 nanoplates with oxygen vacancies as efficient catalysts for the oxygen evolution reaction. Electrochimica Acta 324:134868. https://doi.org/10.1016/j.electacta.2019.134868 Pan J, Du J, Sun Y, et al (2009) The change of structure and electrochemical property in the synthesis process of spherical NiOOH. Electrochimica Acta 54:3812–3818. https://doi.org/10.1016/j.electacta. 2009.01.083 Hall DS, Lockwood DJ, Bock C, MacDougall BR (2015) Nickel hydroxides and related materials: a review of their structures, synthesis and properties. Proc R Soc Math Phys Eng Sci 471:20140792. https://doi.org/10.1098/rspa.2014.0792 Long G, Chen L, Chen X, et al (2025) Interface engineering in Ni(OH) 2 /NiOOH heterojunction to enhance energy-efficient hydrogen production via urea electrolysis. J Colloid Interface Sci 680:880–889. https://doi.org/10.1016/j.jcis.2024.11.023 Lyu C, Zhang L, He D, et al (2022) Micrometer-sized NiOOH hierarchical spheres for enhanced degradation of sulfadiazine via synergistic adsorption and catalytic oxidation in peroxymonosulfate system. Chin Chem Lett 33:930–934. https://doi.org/10.1016/j.cclet.2021.07.012 Shangguan E, Tang H, Chang Z, et al (2011) Effects of different Ni(OH) 2 precursors on the structure and electrochemical properties of NiOOH. Int J Hydrog Energy 36:10057–10064. https://doi.org/ 10.1016/j.ijhydene.2011.02.132 He B, Ling Y, Wang Z, et al (2024) Modulating selective interaction of NiOOH with Mg ions for high-performance aqueous batteries. eScience 4:100293. https://doi.org/10.1016/j.esci.2024.100293 Kavinkumar T, Sivagurunathan AT, Kim D-H (2025) Hierarchical assembly of NiMn nanoflowers edged with NiOOH sheets for high-performance oxygen evolution reaction. J Alloys Compd 1010:178314. https://doi.org/10.1016/j.jallcom.2024.178314 Li X, Han G-Q, Liu Y-R, et al (2016) NiSe@NiOOH Core–Shell Hyacinth-like Nanostructures on Nickel Foam Synthesized by in Situ Electrochemical Oxidation as an Efficient Electrocatalyst for the Oxygen Evolution Reaction. ACS Appl Mater Interfaces 8:20057–20066. https://doi.org/ 10.1021/acsami.6b05597 Zhang F, Chen Z, Liu J, et al (2024) Reactive oxygen species independent oxidase like nanozyme for dual-mode analysis of α-glucosidase. Chem Eng J 492:152328. https://doi.org/10.1016/j.cej. 2024.152328 Li F-F, Liu Y, Jia W-L, et al (2025) Pd nanoparticles on Zn/Co zeolitic imidazolate frameworks: A H 2 O 2 -free oxidase mimic for dual colorimetric and fluorescent detection of glutathione. Sens Actuators B Chem 429:137294. https://doi.org/10.1016/j.snb.2025.137294 Al Lawati HAJ, Hassanzadeh J, Al-Maqbali L, Morsali A (2025) Fully integrated microfluidic paper-based analytical device for straightforward extraction and estimation of the total phenolic content of olive oil samples. Sens Actuators B Chem 431:137419. https://doi.org/10.1016/ j.snb.2025.137419 Gao H, Sun T, Wang W, et al (2024) Self-Illuminating Copper-Luminol Coordination Polymers for Bioluminescence Imaging of Oxidative Damage. Anal Chem. https://doi.org/10.1021/acs.analchem. 4c04258 Huang C, Zhou W, Guan W, Ye N (2024) Molybdenum disulfide nanosheet induced reactive oxygen species for high-efficiency luminol chemiluminescence. Anal Chim Acta 1295:342324. https:// doi.org/10.1016/j.aca.2024.342324 Lu D, Ge M, Qian F, et al (2024) Single-holed cobalt−nitrogen−carbon hollow structure with oxidase-mimicking activity for the chemiluminescence determination of β−galactosidase activity. Microchim Acta 191:200. https://doi.org/10.1007/s00604-024-06285-5 Scheme 1 Scheme 1 is available in the Supplementary Additional Declarations No competing interests reported. Supplementary Files TableS1.docx TableS2.docx ESM1.pdf GraphicalAbstract.png Graphical Abstract Scheme1.docx Cite Share Download PDF Status: Published Journal Publication published 25 Jun, 2025 Read the published version in Microchimica Acta → Version 1 posted Editorial decision: Revision requested 20 May, 2025 Reviews received at journal 18 May, 2025 Reviews received at journal 09 May, 2025 Reviews received at journal 07 May, 2025 Reviews received at journal 06 May, 2025 Reviewers agreed at journal 05 May, 2025 Reviewers agreed at journal 03 May, 2025 Reviewers agreed at journal 30 Apr, 2025 Reviewers agreed at journal 30 Apr, 2025 Reviewers invited by journal 30 Apr, 2025 Editor assigned by journal 25 Apr, 2025 Submission checks completed at journal 25 Apr, 2025 First submitted to journal 24 Apr, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6520640","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":452225395,"identity":"599ccddf-e439-4f27-b790-974cf7e72d26","order_by":0,"name":"Jiaqian Qi","email":"","orcid":"","institution":"Southwest University","correspondingAuthor":false,"prefix":"","firstName":"Jiaqian","middleName":"","lastName":"Qi","suffix":""},{"id":452225396,"identity":"46cfd9e1-b121-451e-939e-795dad1ea3e1","order_by":1,"name":"Yang Chen","email":"","orcid":"","institution":"Southwest University","correspondingAuthor":false,"prefix":"","firstName":"Yang","middleName":"","lastName":"Chen","suffix":""},{"id":452225398,"identity":"430e21cb-44ef-4e8e-ada4-a49b902b6432","order_by":2,"name":"Jing Chen","email":"","orcid":"","institution":"Southwest University","correspondingAuthor":false,"prefix":"","firstName":"Jing","middleName":"","lastName":"Chen","suffix":""},{"id":452225399,"identity":"b8e8c4c8-f230-4ee7-a8ce-b51b1952bd78","order_by":3,"name":"Funan Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAu0lEQVRIiWNgGAWjYDACCSCuYLCBcHiI1nKGIY10LYdJ0MI/u/nYg4M7ztsb3EhgfPC2jUHenKAld46lGxw8cztxw40EZsO5bQyGOxsIaDGQyDGT/th2O8HsRgKbNG8bQ4LBAYJa8r9JHGw7Zw/Uwv6bSC05bEAtBxi3AW1hJkqLxI00M6CW5MT9Zx42S845J2G4gZAW/hnJz4Ba7Owl25MPfnhTZiNP0BYkwNjAAImmUTAKRsEoGAUUAwD85ED6dS+e5wAAAABJRU5ErkJggg==","orcid":"","institution":"Southwest University","correspondingAuthor":true,"prefix":"","firstName":"Funan","middleName":"","lastName":"Chen","suffix":""}],"badges":[],"createdAt":"2025-04-24 12:08:34","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6520640/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6520640/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00604-025-07318-3","type":"published","date":"2025-06-25T15:56:57+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":82058271,"identity":"be8b41a8-e141-410c-860c-482a8212ea56","added_by":"auto","created_at":"2025-05-06 10:56:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":502837,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e XRD pattern (blue curve) of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs. \u003cstrong\u003eb\u003c/strong\u003e HRTEM image of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs. \u003cstrong\u003ec\u003c/strong\u003e FT-IR spectra of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs. \u003cstrong\u003ed\u003c/strong\u003e High-resolution XPS spectra of Ni 2p. \u003cstrong\u003ee\u003c/strong\u003e High-resolution XPS spectra of O 1s\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/70cce87050193942e380fea6.png"},{"id":82058588,"identity":"a6def545-ac9a-42c4-ae7c-71986f2d3b5a","added_by":"auto","created_at":"2025-05-06 11:04:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":152087,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e kinetic profiles of luminol (ⅰ), NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e (ⅱ), luminol-Ni(OH)\u003csub\u003e2\u003c/sub\u003e (ⅲ) and luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs (ⅳ) systems with the wavelength of the emission at 425 nm. \u003cstrong\u003eb\u003c/strong\u003e CL spectroscopy of luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003ec\u003c/strong\u003e UV-vis absorption spectra of luminol (ⅰ), NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs (ⅱ) and luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs (ⅲ). Experimental conditions: 0.60 mmol·L\u003csup\u003e−1\u003c/sup\u003e luminol, 0.02 mol·L\u003csup\u003e−1\u003c/sup\u003e NaOH, 30 μg·mL\u003csup\u003e−1\u003c/sup\u003e\u003cstrong\u003e \u003c/strong\u003eNiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs, flow rate at 2.00 mL·min\u003csup\u003e−1\u003c/sup\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/66e431f42134850ae0ef28b1.png"},{"id":82059387,"identity":"356ea062-88b8-4126-abfe-3573013b07af","added_by":"auto","created_at":"2025-05-06 11:12:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":195040,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e CL signal of luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs in air, nitrogen and oxygen saturated solution. \u003cstrong\u003eb\u003c/strong\u003e Effects of different radical scavengers on the CL emission of luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs. Experimental conditions: 0.60 mmol·L\u003csup\u003e−1\u003c/sup\u003e luminol, 0.02 mol·L\u003csup\u003e−1\u003c/sup\u003e NaOH, 30 μg·mL\u003csup\u003e−1\u003c/sup\u003e\u003cstrong\u003e \u003c/strong\u003eNiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs, flow rate at 2.00 mL·min\u003csup\u003e−1\u003c/sup\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/1a5241486a0efb20cb70f766.png"},{"id":82058275,"identity":"7b9ae6e8-ddb6-4c13-8551-04d7a6fe008d","added_by":"auto","created_at":"2025-05-06 10:56:05","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":125795,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea \u003c/strong\u003eCL intensity of the probe after adding different concentrations of Mn\u003csup\u003e2+\u003c/sup\u003e.\u003cstrong\u003e b\u003c/strong\u003e Linear relationship between (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e − \u003cem\u003eI\u003c/em\u003e)/\u003cem\u003eI\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e and \u003cem\u003eC\u003c/em\u003e\u003csub\u003eMn²⁺\u003c/sub\u003e (µmol·L\u003csup\u003e−1\u003c/sup\u003e). \u003cstrong\u003ec\u003c/strong\u003e Selectivity assay for the detection of Mn\u003csup\u003e2+\u003c/sup\u003e by monitoring the relative CL intensity, [Cr\u003csup\u003e2+\u003c/sup\u003e] = [K\u003csup\u003e+\u003c/sup\u003e] = [Hg\u003csup\u003e2+\u003c/sup\u003e] = [Ag\u003csup\u003e+\u003c/sup\u003e] = [Ba\u003csup\u003e2+\u003c/sup\u003e] = [Pb\u003csup\u003e2+\u003c/sup\u003e] = [Cd\u003csup\u003e2+\u003c/sup\u003e] = [Na\u003csup\u003e+\u003c/sup\u003e] = [Fe\u003csup\u003e3+\u003c/sup\u003e] = [Zn\u003csup\u003e2+\u003c/sup\u003e] = [Mg\u003csup\u003e2+\u003c/sup\u003e] = [Ca\u003csup\u003e2+\u003c/sup\u003e] = 300 µmol·L\u003csup\u003e−1\u003c/sup\u003e, [Mn\u003csup\u003e2+\u003c/sup\u003e] = 30 µmol·L\u003csup\u003e−1\u003c/sup\u003e. Experimental conditions: 0.60 mmol·L\u003csup\u003e−1\u003c/sup\u003e luminol, 0.02 mol·L\u003csup\u003e−1\u003c/sup\u003e NaOH, 30 μg·mL\u003csup\u003e−1\u003c/sup\u003e\u003cstrong\u003e \u003c/strong\u003eNiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs, flow rate at 2.00 mL·min\u003csup\u003e−1\u003c/sup\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/8f44757bfbb26c8976c12bc6.png"},{"id":85686023,"identity":"963407f2-9101-4c79-9f49-26ed71777b58","added_by":"auto","created_at":"2025-06-30 16:00:56","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1479539,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/8d05b527-6743-4ef3-b8fd-f6a59181adf2.pdf"},{"id":82058585,"identity":"61db670b-b035-446d-b677-2f04e52ccf25","added_by":"auto","created_at":"2025-05-06 11:04:05","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":22438,"visible":true,"origin":"","legend":"","description":"","filename":"TableS1.docx","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/89486e3d58b977f3479b2d12.docx"},{"id":82058273,"identity":"723fb819-088d-4fcc-a839-19a272c5fedb","added_by":"auto","created_at":"2025-05-06 10:56:05","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":17974,"visible":true,"origin":"","legend":"","description":"","filename":"TableS2.docx","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/c9e38eeedfbe8c259cd7ea33.docx"},{"id":82058590,"identity":"18bd0158-3e51-4b30-840f-c0cd0a970fc6","added_by":"auto","created_at":"2025-05-06 11:04:05","extension":"pdf","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":713670,"visible":true,"origin":"","legend":"","description":"","filename":"ESM1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/26951b00e8a1ecdd70c965d1.pdf"},{"id":82058282,"identity":"2786689c-d168-433b-bf57-72a7830b53b9","added_by":"auto","created_at":"2025-05-06 10:56:05","extension":"png","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":152352,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical Abstract\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"GraphicalAbstract.png","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/38f91324724212373332c99e.png"},{"id":82058586,"identity":"d0263b7c-27c3-4bb8-9d90-f0a165d2859f","added_by":"auto","created_at":"2025-05-06 11:04:05","extension":"docx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":124492,"visible":true,"origin":"","legend":"","description":"","filename":"Scheme1.docx","url":"https://assets-eu.researchsquare.com/files/rs-6520640/v1/b7350dd83261bb27d8c37487.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eEnhanced Luminol Chemiluminescence with Oxidase-like Activity of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e Nanoflakes for the Sensitive Detection of Mn\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eChemiluminescence (CL) is a phenomenon in which electronically excited species generated during a chemical reaction return to their ground state, releasing energy in the form of light radiation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Due to its advantages such as high sensitivity, broad linear range, requiring no external light source, as well as its simple instrumentation, ease of operation, and rapid analysis speed, CL analysis has become a powerful trace analysis technique [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. It finds extensive applications in fields such as environmental monitoring [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], biomedical and clinical testing [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], and food safety [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Since the chemiluminescent properties of luminol under alkaline conditions were first documented by Albrecht in 1928 [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], luminol has become one of the most common CL reagents due to its advantages such as simple structure, good water solubility, and low cost. It can generate CL when combined with some common oxidants such as hydrogen peroxide, potassium permanganate, and hypochlorite [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Conventional luminol-based systems are inherently limited by chemical instability and low luminescence efficiency [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This requires the development of novel luminol CL systems that operate without external oxidants to overcome these limitations.\u003c/p\u003e \u003cp\u003eMetal oxyhydroxides demonstrate remarkable catalytic activity owing to their high-valent metal active sites and the charge transfer capability among varying valence states [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Specifically, nickel oxyhydroxides (NiOOH) exhibit superior surface reactivity and electrocatalytic activity, along with non-toxicity, unique structure and biocompatibility, which have been widely applied in urea oxidation reactions[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] and alkaline water electrolysis[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, current research has primarily focused on the electrocatalytic properties of NiOOH, while its potential in optical biosensing remains largely unexplored. Notably, other metal oxyhydroxides have shown exceptional performance in oxidant-free optical detection systems, FeOOH nanorods [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] enabled luminol CL-based ultrasensitive detection of uric acid, CoOOH nanosheets [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] directly oxidized luminol for glutathione sensing. These studies clearly demonstrate the enzyme-like catalytic potential of metal oxyhydroxides. Building upon these findings, we systematically investigated the oxidase-like activity of NiOOH and developed a novel oxidant-free luminol chemiluminescence system, thereby expanding the application frontiers of NiOOH in optical biosensing.\u003c/p\u003e \u003cp\u003eManganese ions (Mn\u003csup\u003e2+\u003c/sup\u003e) serve as crucial trace elements in human physiology, playing essential roles in numerous enzymatic processes and metabolic pathways [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Chronic exposure to excessive Mn\u0026sup2;⁺ levels may trigger irreversible Parkinsonian-like neurodegeneration, while occupational or environmental exposure can lead to cognitive impairment and motor coordination deficits [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Therefore, precise quantification of Mn\u003csup\u003e2+\u003c/sup\u003e concentrations in both tap water and environmental water samples carries significant analytical importance. Extensive research efforts have been devoted to developing analytical techniques for Mn\u003csup\u003e2+\u003c/sup\u003e detection in aqueous solutions, primarily including inductively coupled plasma techniques (ICP) [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], atomic absorption spectroscopy (AAS) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], spectrophotometry [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], electrochemical sensor [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], fluorescence spectroscopy [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], and so on. Although these methods exhibit good sensitivity for Mn\u003csup\u003e2+\u003c/sup\u003e detection, they still present certain limitations. For instance, AAS and ICP-MS require lengthy sample pretreatment and instrument calibration, along with expensive equipment and complex operations, Spectrophotometry and fluorometry rely on external light sources and may be interfered with by sample matrices and impurities [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. In contrast, CL detection offers distinct advantages for Mn\u0026sup2;⁺ monitoring, including operational simplicity without requiring external light sources and rapid response times (\u0026lt;\u0026thinsp;1 minute). These characteristics position CL as a particularly promising technique for Mn\u0026sup2;⁺ detection.\u003c/p\u003e \u003cp\u003eIn this work, Ni(OH)\u003csub\u003e2\u003c/sub\u003e nanoflakes incorporating amorphous NiOOH (NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs) was synthesized through a chemical oxidation method. The material preserved the two-dimensional structure of Ni(OH)\u003csub\u003e2\u003c/sub\u003e nanoflakes with a large specific surface area, while the incorporated amorphous NiOOH exhibited inherent flexibility and abundant active sites [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. we discovered that NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs can dramatically enhance the CL intensity of luminol in an oxidant-free system. This enhancement originates from their intrinsic oxidase-like activity, which catalyzes the generation of reactive oxygen species (ROS) from dissolved oxygen, these ROS subsequently react with luminol anions to produce intense CL emission. Significant CL quenching was observed upon Mn\u003csup\u003e2+\u003c/sup\u003e addition, indicating high selectivity and sensitivity toward Mn\u003csup\u003e2+\u003c/sup\u003e detection. Utilizing this phenomenon, we constructed a novel CL sensor for Mn\u003csup\u003e2+\u003c/sup\u003e detection in water samples, which offers rapid analysis and simple operation.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e2.1. Synthesis of NiOOH/Ni(OH)₂ NFs\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eThe synthesis of Ni(OH)₂ nanoflakes was performed according to the reported procedure [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. 0.9 g of NiSO\u003csub\u003e4\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO was dissolved in 60 mL deionized water with constant stirring for 30 min at ambient temperature. Subsequently, 15 mL of NaOH solution (1 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) was added, and the mixture was stirred for an additional 30 minutes. The solution was transferred to a 100 mL autoclave and heated at 200\u0026deg;C for 12 hours. The resulting product was collected by centrifugation, washed repeatedly with deionized water, and dried under vacuum at 60\u0026deg;C overnight, obtaining a pale green powder.\u003c/p\u003e \u003cp\u003eFor the preparation of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs, 0.25 g of Ni(OH)\u003csub\u003e2\u003c/sub\u003e and 0.6 g of NaOH were added to 10 mL K\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e8\u003c/sub\u003e solution (5 mg\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). The mixture was stirred at 200 rpm for 3 hours, followed by centrifugation to collect the precipitate. The obtained precipitate was washed three times with deionized water and then dried overnight at 60\u0026deg;C to yield a black powder.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. CL analysis program\u003c/h2\u003e \u003cp\u003eThe flow injection chemiluminescence (FI-CL) analysis system, schematically illustrated in Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e. The system configuration consists of two peristaltic pumps and a photomultiplier tube (PMT), connected by PTFE tubing with dimensions of 1 mm (inner diameter) and 3 mm (outer diameter). In the experiment, 1000 \u0026micro;L of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs was mixed with 500 \u0026micro;L of Mn\u003csup\u003e2+\u003c/sup\u003e solutions at varying concentrations. The mixture was injected into the system using pump P1, while pump P2 delivered the alkaline luminol solution (containing NaOH). Both solutions were transported through PTFE tubing to the reaction cell, where CL emission was detected. The light signals were amplified by the PMT and subsequently recorded using BPCL software on a Windows XP system\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Detection of Mn\u003csup\u003e2+\u003c/sup\u003e in water samples\u003c/h2\u003e \u003cp\u003eUntreated tap water samples were directly used to assess the sensor performance. Lake water samples were settled for 12 hours to sediment silt, followed by filtration using a syringe equipped with a 0.22 \u0026micro;m membrane filter. Working solutions were prepared by combining 1000 \u0026micro;L NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs with 500 \u0026micro;L water samples spiked with Mn\u003csup\u003e2+\u003c/sup\u003e (5, 15, 25 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Characterization of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs\u003c/h2\u003e\n \u003cp\u003eThe XRD pattern in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ea shows characteristic peaks at 19.0 \u0026deg;, 33.1 \u0026deg;, 38.5 \u0026deg;, and 52.1 \u0026deg;, corresponding to the (001), (100), (101), and (102) crystallographic planes of \u0026beta;-Ni(OH)\u003csub\u003e2\u003c/sub\u003e (JCPDS 14\u0026ndash;0117), respectively. The weaker broad diffraction peaks at 37.3 \u0026deg; and 66.6 \u0026deg; are attributed to amorphous NiOOH [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e]. From the TEM images (Fig S2), horizontally or vertically oriented hexagonal nanosheets can be observed. The HRTEM images (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eb) demonstrate the lattice spacings of 0.272 nm and 0.459 nm for the (100) and (001) planes of Ni(OH)\u003csub\u003e2\u003c/sub\u003e [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e]. The absence of distinct lattice fringes in the region marked by the blue squares further confirms the formation of amorphous NiOOH [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e], consistent with the XRD results. The above analysis demonstrates the successful synthesis of Ni(OH)\u003csub\u003e2\u003c/sub\u003e nanosheets incorporating amorphous NiOOH.\u003c/p\u003e\n \u003cp\u003eThe surface functional groups of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs were analyzed using FT-IR spectroscopy. Figure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec showed a characteristic peak at 3635 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, corresponding to the free O-H stretching vibration. The broad band at 3450 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was assigned hydrogen-bonded O-H stretching vibrations from hydroxyl groups and water molecules. Additionally, the band at 1631 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was attributed to the bending vibration of water molecules, confirming the presence of surface-adsorbed water on the NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. The low-frequency band at approximately 1379 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be ascribed to the vibration of carbonate ions, resulting from CO\u003csub\u003e2\u003c/sub\u003e adsorption in the open synthesis environment. Additionally, the strong and sharp band centered at 524 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was associated with the Ni-O-H bending vibrations and Ni\u003csup\u003e3+\u003c/sup\u003e-O stretching vibrations [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe elemental composition and chemical states of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs were further investigated by XPS. The survey spectrum (Fig. S3) confirms the presence of Ni and O elements. In the high-resolution Ni 2p spectrum (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ed), two spin-orbit doublets were observed, corresponding to Ni 2p\u003csub\u003e3/2\u003c/sub\u003e and Ni 2p\u003csub\u003e1/2\u003c/sub\u003e. The peaks at 856.4 and 874.2 eV were assigned to Ni\u003csup\u003e3+\u003c/sup\u003e, whereas those at 855.3 eV and 872.8 eV are attributed to Ni\u003csup\u003e2+\u003c/sup\u003e. The observed binding energies and peak separation were characteristic of mixed-valence nickel compounds [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. The high-resolution O 1s XPS spectrum (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ee) can be deconvoluted into three distinct components, representing different oxygen chemical environments: the peak at 529.3 eV was attributed to Ni-O bonds, 530.9 eV to O-H groups, and 532.2 eV to adsorbed water or oxygen species. [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003e\u003cstrong\u003e3.2 Oxidase-like activity of NiOOH/Ni(OH)\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e \u003cstrong\u003eNFs\u003c/strong\u003e\u003c/h2\u003e\n \u003cp\u003eThe oxidase-like activity of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs was examined using TMB as the substrate, and the formation of oxidized TMB (oxTMB) was tracked by UV-Vis spectroscopy. As shown in Fig. S4, no significant absorption peaks were observed in the visible range when TMB or NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs were tested individually. However, upon the addition of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs to the TMB solution, the solution rapidly changed from colorless to blue (inset in the upper right corner of the Fig. S4), and a peak at 650 nm assigned to oxTMB was observed [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e]. Furthermore, no oxTMB formation was detected when Ni(OH)\u003csub\u003e2\u003c/sub\u003e or Ni\u003csup\u003e2+\u003c/sup\u003e was added to TMB. These results demonstrate that NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs exhibits excellent oxidase-like activity.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3 Catalytic activity of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs for luminol CL system\u003c/h2\u003e\n \u003cp\u003eThe CL kinetics of the luminol- NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs system were obtained using the FL-CL system. As shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea, the alkaline luminol solution alone produces minimal CL, and Ni(OH)\u003csub\u003e2\u003c/sub\u003e does not enhance the CL signal. However, the addition of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs results in a dramatic CL enhancement, approximately 2,000 times stronger than alkaline luminol alone, demonstrating the excellent catalytic activity of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs in the luminol CL system. The enhanced catalytic activity is likely due to the high specific surface area and abundant active sites provided by the two-dimensional NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs structure. Key experimental parameters, including luminol concentration, NaOH concentration, NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs concentration, and flow rate, were optimized to achieve optimal catalytic performance. Based on the optimization results shown in Fig. S5, the following conditions were selected for subsequent experiments: 0.6 mmol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e luminol, 0.02 mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e NaOH, 30 \u0026micro;g\u0026middot;mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs, and a flow rate of 2.00 mL\u0026middot;min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eTo elucidate the chemiluminescent species generated in the luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs system, the CL emission spectrum was acquired using a fluorescence spectrophotometer operated in CL mode (xenon lamp off). As depicted in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb, the system exhibits a characteristic emission maximum at 425 nm, which corresponds precisely to the known luminescence of the excited-state 3-aminophthalate anion (3-APA*), the oxidation product of luminol. This spectral evidence confirms that the CL mechanism involves the formation of 3-APA* through the catalytic oxidation of luminol by NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e]. Additionally, the UV-Vis absorption spectrum of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs after the CL reaction was studied. As illustrated in the Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec, compared to the individual NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs and luminol systems, the maximum absorption position of the luminol- NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs system shows no change, indicating that the addition of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs does not generate new species [\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e]. This further confirms that NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs acts solely as a catalyst in the system.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e3.4 CL mechanism of luminol with NiOOH/Ni(OH)\u003c/strong\u003e \u003csub\u003e\u0026nbsp;\u003cstrong\u003e2\u003c/strong\u003e\u0026nbsp;\u003c/sub\u003e \u003cstrong\u003eNFs systems\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eThe system operated without exogenous oxidants. To verify dissolved oxygen as the reactive oxygen species (ROS) source for the luminol CL reaction catalyzed by NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs, all test reagents were purged with N\u003csub\u003e2\u003c/sub\u003e/O\u003csub\u003e2\u003c/sub\u003e (30 min), while control reagents were exposed to ambient air under identical conditions. As shown in the Fig. 3a, the CL intensity of the luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs system decreased by approximately 50% under N\u003csub\u003e2\u003c/sub\u003e-saturated conditions, while it increased by about 30% under O\u003csub\u003e2\u003c/sub\u003e-saturated conditions, compared to ambient conditions. These results clearly demonstrate the crucial role of dissolved oxygen in the CL reaction.\u003c/p\u003e\n \u003cp\u003eTo identify the specific ROS involved in the luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs CL system, a series of radical scavenging experiments were systematically conducted. Three well-established scavengers were employed: thiourea(TH) for hydroxyl radicals (\u0026middot;OH), benzoquinone (BQ) for superoxide anions (\u0026middot;O\u0026thinsp;\u0026minus;\u0026thinsp;2), and sodium azide (NaN\u003csub\u003e3\u003c/sub\u003e) for singlet oxygen (\u003csup\u003e1\u003c/sup\u003eO\u003csub\u003e2\u003c/sub\u003e) [\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]. As shown in Fig.\u0026nbsp;3b, in the luminol- NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs system, both BQ and TH significantly reduced the CL intensity, while NaN\u003csub\u003e3\u003c/sub\u003e had a negligible effect on the CL. This indicates that \u0026middot;OH and \u0026middot;O\u0026thinsp;\u0026minus;\u0026thinsp;2 are the primary ROS involved in the CL emission process. To obtain unambiguous evidence of radical generation, electron spin resonance (ESR) spectroscopy was employed using 5,5\u0026prime;-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trapping agent. As shown in Fig. S6, characteristic signals of DMPO/\u0026middot;OH and DMPO/\u0026middot;O\u0026thinsp;\u0026minus;\u0026thinsp;2 adducts were observed, providing direct evidence for the generation of both \u0026middot;OH and \u0026middot;O\u0026thinsp;\u0026minus;\u0026thinsp;2 radicals during the CL reaction.\u003c/p\u003e\n \u003cp\u003eBased on the experimental results, we propose a reaction mechanism for the luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs CL system (Scheme 1). The NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs catalyze the generation of \u0026middot;O\u0026minus; 2 and \u0026middot;OH from dissolved oxygen due to their oxidase-like activity. These ROS then oxidize luminol anion to form excited-state 3-APA*, which emits light at 425 nm when returning to its ground state.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e3.5 Detection of Mn\u003c/strong\u003e \u003csup\u003e\u0026nbsp;\u003cstrong\u003e2+\u003c/strong\u003e\u0026nbsp;\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eLeveraging the reducing properties of Mn\u003csup\u003e2+\u003c/sup\u003e, which effectively scavenges ROS and radicals generated in the system, we developed a highly sensitive CL sensor based on the luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs platform for direct Mn\u003csup\u003e2+\u003c/sup\u003e detection. Under optimized experimental conditions, the CL intensity exhibited a concentration-dependent decrease with increasing Mn\u003csup\u003e2+\u003c/sup\u003e levels, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea. Quantitative analysis revealed an excellent linear relationship between (\u003cem\u003eI\u003c/em\u003e₀ \u0026minus; \u003cem\u003eI\u003c/em\u003e)/\u003cem\u003eI\u003c/em\u003e₀ and Mn\u003csup\u003e2+\u003c/sup\u003e concentration (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb), described by the equation (\u003cem\u003eI\u003c/em\u003e₀ \u0026minus; \u003cem\u003eI\u003c/em\u003e)/\u003cem\u003eI\u003c/em\u003e₀ = 3.02\u003cem\u003eC\u003c/em\u003e\u003csub\u003eMn\u0026sup2;⁺\u003c/sub\u003e + 3.71 (\u003cem\u003eR\u003c/em\u003e\u0026sup2; = 0.9977, n\u0026thinsp;=\u0026thinsp;7), where \u003cem\u003eI\u003c/em\u003e₀ and \u003cem\u003eI\u003c/em\u003e represent the CL intensities in the absence and presence of Mn\u003csup\u003e2+\u003c/sup\u003e, respectively. The linear dynamic range spanned from 1.00 to 30.00 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, with a limit of detection (LOD) of 0.60 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (3\u0026sigma;/k). The analytical precision of the Mn\u003csup\u003e2+\u003c/sup\u003e detection system was evaluated through 11 replicate measurements of a 5 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e Mn\u003csup\u003e2+\u003c/sup\u003e standard solution, yielding a relative standard deviation (RSD) of 3.42%, which demonstrates exceptional method reproducibility. The developed sensor meets the detection requirement of the World Health Organization (WHO) drinking water standard of 1.80 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Mn\u003csup\u003e2+\u003c/sup\u003e and exhibits superior sensitivity with a lower detection limit compared to existing methods, as detailed in Table \u003cspan class=\"InternalRef\"\u003eS1\u003c/span\u003e. Furthermore, the sensor offers significant advantages in terms of rapid response time and operational simplicity, requiring no complex sample pretreatment.\u003c/p\u003e\n \u003cp\u003eTo evaluate the practical applicability of the luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs sensor, we assessed potential interference from common coexisting ions in real water samples, including K\u003csup\u003e+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, Ag\u003csup\u003e+\u003c/sup\u003e, Ca\u003csup\u003e2+\u003c/sup\u003e, Ba\u003csup\u003e2+\u003c/sup\u003e, Zn\u003csup\u003e2+\u003c/sup\u003e, Cr\u003csup\u003e2+\u003c/sup\u003e, Hg\u003csup\u003e2+\u003c/sup\u003e, Pb\u003csup\u003e2+\u003c/sup\u003e, Cd\u003csup\u003e2+\u003c/sup\u003e, and Fe\u003csup\u003e3+\u003c/sup\u003e at 300 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. As illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec, the CL intensity significantly decreased upon the addition of 30 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e Mn\u003csup\u003e2+\u003c/sup\u003e, while other ions showed negligible interference. These results confirmed the high specificity of the sensor for Mn\u003csup\u003e2+\u003c/sup\u003e detection, suggesting its suitability for analyzing real environmental water samples.\u003c/p\u003e\n \u003cp\u003eThe sensor was further applied to detect Mn\u003csup\u003e2+\u003c/sup\u003e in tap water and treated lake water samples. Spike recovery experiments were conducted to validate its practicality. As summarized in the Table S2, recoveries ranged from 96.92\u0026ndash;102.86% for Mn\u003csup\u003e2+\u003c/sup\u003e spiked at 5 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 15 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and 25 \u0026micro;mol\u0026middot;L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in tap water and lake water, with RSD values between 1.32% and 3.58% (n\u0026thinsp;=\u0026thinsp;3). These results demonstrate the reliability and promising potential of this method for efficient Mn\u0026sup2;⁺ determination in real water samples.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eIn summary, we have proposed a novel luminol CL system induced by NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs without the addition of oxidants. The enhancement of luminescence is attributed to the excellent oxidase-like activity of NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs, which can decompose dissolved oxygen to generate various ROS such as \u0026middot;OH and \u0026middot;O\u0026thinsp;\u0026minus;\u0026thinsp;2, leading to the enhancement of CL. Due to the significant inhibitory effect of Mn\u003csup\u003e2+\u003c/sup\u003e on the CL intensity of the luminol-NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs system, a simple, rapid, and sensitive method for detecting Mn\u003csup\u003e2+\u003c/sup\u003e has been developed. This study reveals that NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs is an efficient catalyst for the luminol chemiluminescence reaction, showcasing great potential for applications in the field of chemiluminescence.\u003c/p\u003e"},{"header":"Statements and Declarations","content":"\u003cp\u003eCompeting Interest: We declare that we have no known competing financial interests or personal relationships that could have influenced the work reported in this paper.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFunding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEthical Approval: Our study did not involve human participants, animals, or any ethical issues requiring approval.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAuthor Contributions: All authors contributed to the study conception, design, and manuscript preparation. We approved the final version for submission.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eYang M, Huang J, Fan J, et al (2020) Chemiluminescence for bioimaging and therapeutics: recent advances and challenges. Chem Soc Rev 49:6800\u0026ndash;6815. https://doi.org/10.1039/D0CS00348D\u003c/li\u003e\n \u003cli\u003eLi S, Jiang Y, Huang R, Zhang X (2024) DNA-mediated chemiluminescence bioassays. TrAC Trends Anal Chem 175:117720. https://doi.org/10.1016/j.trac.2024.117720\u003c/li\u003e\n \u003cli\u003eDavid M, Gutkin S, Nithun RV, et al (2025) Unprecedented Photoinduced-Electron-Transfer Probe with a Turn-ON Chemiluminescence Mode-of-Action. Angew Chem Int Ed 64:e202417924. https://doi.org/10.1002/anie.202417924\u003c/li\u003e\n \u003cli\u003eGou J, Qin Y, Tang W, et al (2025) Phosphorus nitride dot-activated ferrate (VI) with enhanced singlet oxygen mediating chemiluminescence for pyroquilon determination. Chem Eng J 505:159477. https://doi.org/10.1016/j.cej.2025.159477\u003c/li\u003e\n \u003cli\u003eLiu J, Huang J, Wei X, et al (2024) Near-Infrared Chemiluminescence Imaging of Chemotherapy-Induced Peripheral Neuropathy. Adv Mater 36:2310605. https://doi.org/10.1002/adma.202310605\u003c/li\u003e\n \u003cli\u003eMao F, Yang X, He Z, et al (2025) Mimotope peptides for nanobodies: A nontoxic alternative to ochratoxin A and its application in chemiluminescence immunoassays for analysis of pepper samples. Food Chem 465:142061. https://doi.org/10.1016/j.foodchem.2024.142061\u003c/li\u003e\n \u003cli\u003eAlbrecht HO (1928) \u0026Uuml;ber die Chemiluminescenz des Aminophthals\u0026auml;urehydrazids. Z F\u0026uuml;r Phys Chem 136U:321\u0026ndash;330. https://doi.org/10.1515/zpch-1928-13625\u003c/li\u003e\n \u003cli\u003eDong Z, Du F, Hanif S, et al (2024) Development of chemiluminescent systems and devices for analytical applications. Chem Commun 60:11837\u0026ndash;11848. https://doi.org/10.1039/D4CC04414B\u003c/li\u003e\n \u003cli\u003eJiang Y, Yang X, Li S, et al (2024) Chemiluminescence initiated by nebulization of oxidant- and catalyst-free aqueous luminol solutions. Chem Eng J 481:148753. https://doi.org/10.1016/ j.cej.2024.148753\u003c/li\u003e\n \u003cli\u003eDeepa S, Venkatesan R, Jayalakshmi S, et al (2023) Recent advances in catalyst-enhanced luminol chemiluminescence system and its environmental and chemical applications. J Environ Chem Eng 11:109853. https://doi.org/10.1016/j.jece.2023.109853\u003c/li\u003e\n \u003cli\u003eXu L, Li M, Zhao F, et al (2024) Low oxidation state engineering in transition metal-based interfacial regulation layer accelerates charge transfer kinetics toward enhanced photoelectrochemical water splitting. Appl Catal B Environ Energy 359:124503. https://doi.org/10.1016/j.apcatb.2024.124503\u003c/li\u003e\n \u003cli\u003eTheerthagiri J, Karuppasamy K, Justin Raj C, et al (2024) Structural engineering of metal oxyhydroxide for electrochemical energy conversion and storage. Coord Chem Rev 513:215880. https://doi.org/10.1016/j.ccr.2024.215880\u003c/li\u003e\n \u003cli\u003eLi X, Ma S, Tu L, et al (2025) Efficient urea removal with hydroperoxide production in bipolar membrane electrochemical cell using MoNiOOH nanoarray anode electrocatalyst. Appl Catal B Environ Energy 370:125158. https://doi.org/10.1016/j.apcatb.2025.125158\u003c/li\u003e\n \u003cli\u003eShi F, Xiao L, Zhou Z, et al Accelerating the Transformation of Active \u0026beta;-NiOOH on NiFe Layered Double Hydroxide via Cation\u0026ndash;anion Collaborative Coordination for Alkaline Water Oxidation at High Current Densities. Adv Funct Mater n/a:2501070. https://doi.org/10.1002/adfm.202501070\u003c/li\u003e\n \u003cli\u003eJi K, Xia S, Sang X, et al (2023) Enhanced Luminol Chemiluminescence with Oxidase-like Properties of FeOOH Nanorods for the Sensitive Detection of Uric Acid. Anal Chem 95:3267\u0026ndash;3273. https://doi.org/10.1021/acs.analchem.2c04247\u003c/li\u003e\n \u003cli\u003eYang XJ, Li RS, Li CM, et al (2020) Cobalt oxyhydroxide nanoflakes with oxidase-mimicking activity induced chemiluminescence of luminol for glutathione detection. Talanta 215:120928. https://doi.org/10.1016/j.talanta.2020.120928\u003c/li\u003e\n \u003cli\u003eObeng SK, Kulh\u0026aacute;nek M, Bal\u0026iacute;k J, et al (2024) Manganese: From Soil to Human Health\u0026mdash;A Comprehensive Overview of Its Biological and Environmental Significance. Nutrients 16:3455. https://doi.org/10.3390/nu16203455\u003c/li\u003e\n \u003cli\u003eMarkiv B, Exp\u0026oacute;sito A, Ruiz-Azcona L, et al (2023) Environmental exposure to manganese and health risk assessment from personal sampling near an industrial source of airborne manganese. Environ Res 224:115478. https://doi.org/10.1016/j.envres.2023.115478\u003c/li\u003e\n \u003cli\u003eHorning KJ, Caito SW, Tipps KG, et al (2015) Manganese Is Essential for Neuronal Health. Annu Rev Nutr 35:71\u0026ndash;108. https://doi.org/10.1146/annurev-nutr-071714-034419\u003c/li\u003e\n \u003cli\u003eRamachandran M, Schwabe KA, Ying SC (2021) Shallow Groundwater Manganese Merits Deeper Consideration. Environ Sci Technol 55:3465\u0026ndash;3466. https://doi.org/10.1021/acs.est.0c08065\u003c/li\u003e\n \u003cli\u003eAlkas FB, Shaban JA, Sukuroglu AA, et al (2017) Monitoring and assessment of heavy metal/metalloid concentration by inductively coupled plasma mass spectroscopy (ICP-MS) method in Gonyeli Lake, Cyprus. Environ Monit Assess 189:516. https://doi.org/10.1007/s10661-017-6222-x\u003c/li\u003e\n \u003cli\u003eShilina Y, Ziv B, Meir A, et al (2016) Combined Electron Paramagnetic Resonance and Atomic Absorption Spectroscopy/Inductively Coupled Plasma Analysis As Diagnostics for Soluble Manganese Species from Mn-Based Positive Electrode Materials in Li-ion Cells. Anal Chem 88:4440\u0026ndash;4447. https://doi.org/10.1021/acs.analchem.6b00204\u003c/li\u003e\n \u003cli\u003eXu Y, Xu F, Liu Y, et al (2025) The clean analysis process of Mn\u003csup\u003e2+\u003c/sup\u003e for industries: a comparative study on direct determination of high-concentration Mn\u003csup\u003e2+\u003c/sup\u003e in solution using spectrophotometry. BMC Chem 19:21. https://doi.org/10.1186/s13065-024-01367-0\u003c/li\u003e\n \u003cli\u003eBoselli E, Wu Z, Friedman A, et al (2021) Validation of Electrochemical Sensor for Determination of Manganese in Drinking Water. Environ Sci Technol 55:7501\u0026ndash;7509. https://doi.org/10.1021/ acs.est.0c05929\u003c/li\u003e\n \u003cli\u003eYang L, Huang K, Li X, et al (2024) Fluorescence switching sensor for sensitive detection of curcumin/Mn\u003csup\u003e2+\u003c/sup\u003e using biomass carbon quantum dots: A combination of experimental and theoretical insights. J Environ Chem Eng 12:114533. https://doi.org/10.1016/j.jece.2024.114533\u003c/li\u003e\n \u003cli\u003eAlosaimi EH Recent Developments in Colorimetric and Fluorimetric Chemosensors for the Detection of Mn\u003csup\u003e2+\u003c/sup\u003e Ions: A Review (2010\u0026ndash;2024). Crit Rev Anal Chem 0:1\u0026ndash;21. https://doi.org/ 10.1080/10408347.2025.2460091\u003c/li\u003e\n \u003cli\u003eZhang H, He X, Dong K, et al (2023) Selenate promoted stability improvement of nickel selenide nanosheet array with an amorphous NiOOH layer for seawater oxidation. Mater Today Phys 38:101249. https://doi.org/10.1016/j.mtphys.2023.101249\u003c/li\u003e\n \u003cli\u003eWang T, Li X, Pang Y, et al (2021) Unlocking the synergy of interface and oxygen vacancy by core-shell nickel phosphide@oxyhydroxide nanosheets arrays for accelerating alkaline oxygen evolution kinetics. Chem Eng J 425:131491. https://doi.org/10.1016/j.cej.2021.131491\u003c/li\u003e\n \u003cli\u003eKim N, Lim D, Choi Y, et al (2019) Hexagonal \u0026beta;-Ni(OH)\u003csub\u003e2\u003c/sub\u003e nanoplates with oxygen vacancies as efficient catalysts for the oxygen evolution reaction. Electrochimica Acta 324:134868. https://doi.org/10.1016/j.electacta.2019.134868\u003c/li\u003e\n \u003cli\u003ePan J, Du J, Sun Y, et al (2009) The change of structure and electrochemical property in the synthesis process of spherical NiOOH. Electrochimica Acta 54:3812\u0026ndash;3818. https://doi.org/10.1016/j.electacta. 2009.01.083\u003c/li\u003e\n \u003cli\u003eHall DS, Lockwood DJ, Bock C, MacDougall BR (2015) Nickel hydroxides and related materials: a review of their structures, synthesis and properties. Proc R Soc Math Phys Eng Sci 471:20140792. https://doi.org/10.1098/rspa.2014.0792\u003c/li\u003e\n \u003cli\u003eLong G, Chen L, Chen X, et al (2025) Interface engineering in Ni(OH)\u003csub\u003e2\u003c/sub\u003e/NiOOH heterojunction to enhance energy-efficient hydrogen production via urea electrolysis. J Colloid Interface Sci 680:880\u0026ndash;889. https://doi.org/10.1016/j.jcis.2024.11.023\u003c/li\u003e\n \u003cli\u003eLyu C, Zhang L, He D, et al (2022) Micrometer-sized NiOOH hierarchical spheres for enhanced degradation of sulfadiazine via synergistic adsorption and catalytic oxidation in peroxymonosulfate system. Chin Chem Lett 33:930\u0026ndash;934. https://doi.org/10.1016/j.cclet.2021.07.012\u003c/li\u003e\n \u003cli\u003eShangguan E, Tang H, Chang Z, et al (2011) Effects of different Ni(OH)\u003csub\u003e2\u003c/sub\u003e precursors on the structure and electrochemical properties of NiOOH. Int J Hydrog Energy 36:10057\u0026ndash;10064. https://doi.org/ 10.1016/j.ijhydene.2011.02.132\u003c/li\u003e\n \u003cli\u003eHe B, Ling Y, Wang Z, et al (2024) Modulating selective interaction of NiOOH with Mg ions for high-performance aqueous batteries. eScience 4:100293. https://doi.org/10.1016/j.esci.2024.100293\u003c/li\u003e\n \u003cli\u003eKavinkumar T, Sivagurunathan AT, Kim D-H (2025) Hierarchical assembly of NiMn nanoflowers edged with NiOOH sheets for high-performance oxygen evolution reaction. J Alloys Compd 1010:178314. https://doi.org/10.1016/j.jallcom.2024.178314\u003c/li\u003e\n \u003cli\u003eLi X, Han G-Q, Liu Y-R, et al (2016) NiSe@NiOOH Core\u0026ndash;Shell Hyacinth-like Nanostructures on Nickel Foam Synthesized by in Situ Electrochemical Oxidation as an Efficient Electrocatalyst for the Oxygen Evolution Reaction. ACS Appl Mater Interfaces 8:20057\u0026ndash;20066. https://doi.org/ 10.1021/acsami.6b05597\u003c/li\u003e\n \u003cli\u003eZhang F, Chen Z, Liu J, et al (2024) Reactive oxygen species independent oxidase like nanozyme for dual-mode analysis of \u0026alpha;-glucosidase. Chem Eng J 492:152328. https://doi.org/10.1016/j.cej. 2024.152328\u003c/li\u003e\n \u003cli\u003eLi F-F, Liu Y, Jia W-L, et al (2025) Pd nanoparticles on Zn/Co zeolitic imidazolate frameworks: A H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e-free oxidase mimic for dual colorimetric and fluorescent detection of glutathione. Sens Actuators B Chem 429:137294. https://doi.org/10.1016/j.snb.2025.137294\u003c/li\u003e\n \u003cli\u003eAl Lawati HAJ, Hassanzadeh J, Al-Maqbali L, Morsali A (2025) Fully integrated microfluidic paper-based analytical device for straightforward extraction and estimation of the total phenolic content of olive oil samples. Sens Actuators B Chem 431:137419. https://doi.org/10.1016/ j.snb.2025.137419\u003c/li\u003e\n \u003cli\u003eGao H, Sun T, Wang W, et al (2024) Self-Illuminating Copper-Luminol Coordination Polymers for Bioluminescence Imaging of Oxidative Damage. Anal Chem. https://doi.org/10.1021/acs.analchem. 4c04258\u003c/li\u003e\n \u003cli\u003eHuang C, Zhou W, Guan W, Ye N (2024) Molybdenum disulfide nanosheet induced reactive oxygen species for high-efficiency luminol chemiluminescence. Anal Chim Acta 1295:342324. https:// doi.org/10.1016/j.aca.2024.342324\u003c/li\u003e\n \u003cli\u003eLu D, Ge M, Qian F, et al (2024) Single-holed cobalt\u0026minus;nitrogen\u0026minus;carbon hollow structure with oxidase-mimicking activity for the chemiluminescence determination of \u0026beta;\u0026minus;galactosidase activity. Microchim Acta 191:200. https://doi.org/10.1007/s00604-024-06285-5\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme 1","content":"\u003cp\u003eScheme 1 is available in the Supplementary \u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"chemiluminescence, luminol, nickel oxyhydroxides, oxidase-like, Mn2+","lastPublishedDoi":"10.21203/rs.3.rs-6520640/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6520640/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eNickel hydroxide nanoflakes incorporating amorphous nickel oxyhydroxide (NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs) were synthesized through a chemical oxidation approach. NiOOH/Ni(OH)\u003csub\u003e2\u003c/sub\u003e NFs maintains the two-dimensional structure of Ni(OH)\u003csub\u003e2\u003c/sub\u003e nanoflakes with an enlarged specific surface area. Furthermore, the amorphous NiOOH possesses abundant high-valence nickel active sites, endowing the material with remarkable oxidase-like activity. This catalytic property enabled the generation of reactive oxygen species (ROS) from dissolved oxygen, enhancing the luminol chemiluminescence (CL) intensity by over 2,000-fold without requiring external oxidants. Mn\u003csup\u003e2+\u003c/sup\u003e significantly quenched the CL signal by scavenging ROS, enabling a linear detection range of 1‒30 μmol·L\u003csup\u003e−1\u003c/sup\u003e and a detection limit of 0.60 μmol·L\u003csup\u003e−1\u003c/sup\u003e, which is 3-fold lower than the World Health Organization (WHO) permissible limit (1.80 μmol·L\u003csup\u003e−1\u003c/sup\u003e) for drinking water. The sensor was successfully applied to tap and lake water samples, demonstrating simplicity, rapid response, and high selectivity, making it a promising method for environmental monitoring.\u003c/p\u003e","manuscriptTitle":"Enhanced Luminol Chemiluminescence with Oxidase-like Activity of NiOOH/Ni(OH)2 Nanoflakes for the Sensitive Detection of Mn2+","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-06 10:56:00","doi":"10.21203/rs.3.rs-6520640/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-20T04:50:29+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-18T18:53:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-09T13:20:56+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-08T03:05:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-06T04:06:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"242243971378307629391552423458944866568","date":"2025-05-06T02:37:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"208641193495185473129490914213738897723","date":"2025-05-03T07:47:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"284722687320673197042624317132683508654","date":"2025-04-30T23:57:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"267313843356421365041580398750242436448","date":"2025-04-30T16:56:59+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-30T16:54:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-25T12:33:42+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-04-25T12:29:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microchimica Acta","date":"2025-04-24T12:03:15+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a13a9f33-8427-42fc-a302-b5efb4c05a15","owner":[],"postedDate":"May 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-06-30T15:58:20+00:00","versionOfRecord":{"articleIdentity":"rs-6520640","link":"https://doi.org/10.1007/s00604-025-07318-3","journal":{"identity":"microchimica-acta","isVorOnly":false,"title":"Microchimica Acta"},"publishedOn":"2025-06-25 15:56:57","publishedOnDateReadable":"June 25th, 2025"},"versionCreatedAt":"2025-05-06 10:56:00","video":"","vorDoi":"10.1007/s00604-025-07318-3","vorDoiUrl":"https://doi.org/10.1007/s00604-025-07318-3","workflowStages":[]},"version":"v1","identity":"rs-6520640","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6520640","identity":"rs-6520640","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}