Compressive Strain Boosts IrBa-Co3O4 for Acidic Water Oxidation

Compressive Strain Boosts IrBa-Co3O4 for Acidic Water Oxidation | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 21 April 2025 V1 Latest version Share on Compressive Strain Boosts IrBa-Co3O4 for Acidic Water Oxidation Authors : Mengtian Huo , Qianyu Li , Yu Liang , Wei Liu , Huiying Wang , Kaichi Qin , Xinran Sun , Yue Ma , Zihao Xing , and Jinfa Chang 0000-0002-5066-3625 [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.174520647.78729472/v1 311 views 206 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Iridium (Ir)-based materials are promising candidates for acidic oxygen evolution reaction (OER) but face challenges such as high cost and aggregation. In this study, we synthesized a low-Ir-content catalyst (1.47 at. %) via electrodeposition, where barium (Ba) doping introduces compressive strain to optimize Ir active sites while mitigating Ir aggregation into clusters or nanoparticles. Structural analyses, including X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), and extended X-ray absorption fine structure (EXAFS), confirm atomic-level dispersion of Ir and Ba, lattice contraction, and shortened Co-O bonds. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) reveal electron transfer from Ir to Co/Ba, elevating Ir’s oxidation state and enhancing OER activity. In 0.5 M H2SO4, the IrBa-Co3O4 catalyst achieves 10 mA cm-2 at an overpotential of 251 mV and operates stable for 100 hours, outperforming most reported spinel type catalysts. In-situ Raman spectroscopy and XANES attribute the improved kinetics to compressive-strain-induced octahedral Co-oxygen (Cooct-O) bond shortening and optimized Ir-O-Ba/Co coordination. This work demonstrates a strategy for designing cost-effective, durable acidic OER catalysts through synergistic doping and strain engineering. Cite this paper: Chin. J. Chem. 2024 , 42 , XXX—XXX. DOI: 10.1002/cjoc.202400XXX Compressive Strain Boosts IrBa-Co 3 O 4 for Acidic Water Oxidation Mengtian Huo, a, # Qianyu Li, a, # Yu Liang a Wei Liu, a Huiying Wang, a Kaichi Qin, a Xinran Sun, a Yue Ma, a Zihao Xing,* , a, Jinfa Chang* , a a Faculty of Chemistry, Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, Northeast Normal University, Changchun 130024, PR China # These authors contributed equally. “‘latex oxygen evolution reaction | iridium catalysts | compressive strain | transition metal oxides | lattice contraction | Comprehensive Summary Iridium (Ir)-based materials are promising candidates for acidic oxygen evolution reaction (OER) but face challenges such as high cost and aggregation. In this study, we synthesized a low-Ir-content catalyst (1.47 at. %) via electrodeposition, where barium (Ba) doping introduces compressive strain to optimize Ir active sites while mitigating Ir aggregation into clusters or nanoparticles. Structural analyses, including X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), and extended X-ray absorption fine structure (EXAFS), confirm atomic-level dispersion of Ir and Ba, lattice contraction, and shortened Co-O bonds. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) reveal electron transfer from Ir to Co/Ba, elevating Ir’s oxidation state and enhancing OER activity. In 0.5 M H2SO4, the IrBa-Co3O4 catalyst achieves 10 mA cm-2 at an overpotential of 251 mV and operates stable for 100 hours, outperforming most reported spinel type catalysts. In-situ Raman spectroscopy and XANES attribute the improved kinetics to compressive-strain-induced octahedral Co-oxygen (Cooct-O) bond shortening and optimized Ir-O-Ba/Co coordination. This work demonstrates a strategy for designing cost-effective, durable acidic OER catalysts through synergistic doping and strain engineering. Background and Originality Content Please show here in this paragraph how original your results are clearly. The editorial team will decide whether this manuscript will be sent out for peer-review. Renewable hydrogen electrolysis benefits from acidic electrolyzers due to their compact cell size, low ohmic losses, high current density, and efficiency [1-6]. However, most oxygen evolution reaction (OER) electrocatalysts, such as nickel-iron (Ni-Fe) oxides/alloys [7-13] and metal hydroxides/nitrides [14-18], exhibit superior performance in alkaline rather than acidic environments. Under strongly acidic and oxidizing conditions, these catalysts suffer from sluggish kinetics and degradation, limiting their efficacy and stability [19-22]. Iridium (Ir)-based materials have emerged as the most viable candidates for industrial acidic OER electrocatalysts due to their activity and stability [4, 23-25]. However, Ir’s scarcity and high cost [26, 27], coupled with its high atomization enthalpy (669.4 kJ mol -1 ), promote aggregation, reducing catalytic activity [28]. Thus, a key challenge is minimizing Ir content while maintain high OER performance [29-32]. Transition metal oxides (TMOs), particularly cobalt-based oxides like Co3O4, offer potential for optimizing Ir active sites due to their flexible lattice structure, tenable d-orbitals, and electron-donating properties [33-35]. However, in acidic media, Co 3 O 4 -based catalysts follow an adsorption evolution mechanism (AEM)[36, 37], involving multiple oxygen intermediates that slow catalytic performance and stability. In alkaline/neutral media, Co 3 O 4 enables direct O-O radical coupling, enhancing OER activity [38, 39]. In acidic conditions, achieving the optimal Co 3 O 4 -Ir distance to activate the dual oxygen mechanism (DOM) pathway remains challenging. A promising solution is introducing compressive strain via exogenous atoms doping [40, 41], which shortens interatomic distances and enables controllable lattice contraction. Barium (Ba), with its larger atomic radius, stabilizes Co 3 O 4 ’s bulk phase and induces compressive strain, reducing the Co-O-Co bond distances. Here, we prepared Co 3 O 4 -supported Ir catalysts via electrodeposition, reducing Ir content to 1.473 atom% while preventing aggregation. This approach maximizes the electrochemically active surface area, suppresses particle migration/agglomeration, and establishes efficient mass transport, improving both activity and stability. The IrBa-Co 3 O 4 catalyst achieves 10 mA cm -2 in 0.5 M H 2 SO 4 at 251 mV overpotential with 100-hour stability. XAFS and in-situ Raman spectroscopy confirm Ba/Ir doping shortens Co–O–Co bonds, optimizing Ir–Co and Co–O distances to enhance acidic OER performance. This work offers an effective chemical approach to activate the DOM pathway, advancing acidic OER catalysis. Results and Discussion Please show your observations here followed by discussion leading to scientific rules and/or conclusion with Tables and Figures. Synthesis and structural characterization of IrBa-Co 3 O 4 The target catalyst, IrBa-Co 3 O 4 , was synthesized following the procedure illustrated in Figure 1a . Scanning electron microscopy (SEM) images ( Figures 1b, c ) reveal that the material exhibits a uniform nanosheet morphology, with each nanosheet approximately 0.8 nm in length, evenly dispersed on a carbon cloth substrate. This nanostructure enhances the contact area between the material and the electrolyte, thereby increasing the availability of active Ir sites. The impregnation method used to incorporate Ir into the Ba-Co 3 O 4 precursor ensures optimal dispersion of Ir active sites on the surface, maximizing catalytic efficiency even at ultra-low loadings. Aberration-corrected scanning transmission electron microscopy (AC-STEM) images (Figure 1d ) of Ba-Co 3 O 4 reveal distinct lattice fringes corresponding to the (111) and (311) planes of Co 3 O 4 . Compared to pure Co 3 O 4 , the lattice spacings of the (311) and (400) planes in IrBa-Co 3 O 4 decrease from 0.202 nm to 0.191 nm and 0.243 nm to 0.241 nm, respectively, indicating significant lattice contraction due to Ir and Ba doping. The observed brightness variations further confirm the atomic-level dispersion of Ir and Ba. Selected area electron diffraction (SAED) patterns ( Figure 1e ) confirm the polycrystalline nature of the material, with all discernible rings corresponding to Co₃O₄. Inductively coupled plasma optical emission spectroscopy (ICP-OES) verified the successful incorporation of Ir and Ba, with an optimized atomic ratio of 89.06% Co : 1.47% Ir : 9.47% Ba (Table S1). Additionally, energy-dispersive spectroscopy (EDS) elemental mapping ( Figures 1f-j ) corroborated the uniform distribution of Ir and Ba within the structure. For comparison, control samples (Ba-Co₃O₄, Ir-Co₃O₄, and Co₃O₄) were prepared using the same method and subjected to physical characterization ( Figures S1–S3 ) and electrochemical testing. Electronic structure and atomic structure analysis of IrBa-Co 3 O 4 X-ray diffraction (XRD) patterns ( Figure 2a ) of IrBa-Co 3 O 4 , Ba-Co 3 O 4 , Ir-Co 3 O 4 , and Co 3 O 4 exhibit characteristic peaks corresponding to the spinel Co 3 O 4 phase (JCPDS 43-1003). A comparison the XRD characteristic patterns reveals that the diffraction peaks of the doped materials shift to higher angles relative to Co 3 O 4 , with the degree of shift following the order: Ir-Co 3 O 4 > Ba-Co 3 O 4 > IrBa-Co 3 O 4 . This indicates that Ir and Ba doping induces lattice contraction in Co 3 O 4 , with the most pronounced effect observed in IrBa-Co 3 O 4 , likely due to the larger atomic radii of Ir and Ba exerting compressive strain on the lattice [42]. Notably, no secondary phases corresponding to Ir or Ba oxides were detected, suggesting their atomic-level dispersion ( Figure 1d ). Raman spectroscopy ( Figure 2b ) further elucidates the structural modifications induced by doping. The A 1 g peak (representing octahedral Co 3+ sites) at 693.90 cm -1 in Co 3 O 4 undergoes a significant redshift upon Ir and Ba co-doping[43-45], confirming that these dopants primarily influence the octahedral sites in Co 3 O 4 . X-ray photoelectron spectroscopy (XPS) was employed to investigate the electronic states of the material. The Co 2p spectrum (Figure S4a) of Co 3 O 4 exhibits peaks at 780.2 eV (Co³⁺) and 781.9 eV (Co 2 ⁺), along with satellite features near 787.0 eV[33, 44]. While Ba-Co 3 O 4 shows minimal changes in the Co 2p region, the introduction of Ir leads to a decrease in the 2p 3/2 binding energy in Ir-Co 3 O 4 and IrBa-Co 3 O 4 , suggesting electron transfer frm Ir to Co and Ba. The Ir 4f spectra ( Figure 2c ) of Ir-Co 3 O 4 and IrBa-Co 3 O 4 reveal that the 4f 5/2 (65.3 eV) and 4f 7/2 (62.5 eV) peaks in IrBa-Co 3 O 4 shift to higher binding energies, indicating an increase in the oxidation state of Ir due to electron transfer to Ba. This higher Ir valence state is beneficial for enhanced catalytic activity and stability in OER[23, 46-49]. The Ba 2p spectrum (Figure S4b) supports this conclusion, showing a lower binding energy shift in IrBa-Co 3 O 4 compared to Ba-Co 3 O 4 , confirming electron transfer from Ir to Ba. The O 1s XPS (Figure S4c) was deconvoluted into three components: lattice oxygen (M−O) at 529.8 eV, oxygen vacancies/hydroxyl oxygen (O v /OH) at 531.4 eV, and adsorbed water (O-H 2 O) at 532.5 eV. A 0.6 eV redshift in the O 1s spectrum of IrBa-Co 3 O 4 (relative to Ba-Co 3 O 4 ) suggests stronger surface coupling due to Ir–O x species formation. Additionally, Ir and Ba doping increases the oxygen vacancy (O v ) concentration, with the highest proportion observed in IrBa-Co 3 O 4 . Electron paramagnetic resonance (EPR) spectroscopy ( Figure 2d ) further confirms this trend, showing the strongest signal for IrBa-Co 3 O 4 , attributed to electrons trapped in O v sites. X-ray absorption near edge structure (XANES) analysis of the Co K-edge ( Figure 3a ) reveals that IrBa-Co 3 O 4 exhibits a lower Co oxidation state compared to Co 3 O 4 , consistent with electron donation from Ir/Ba to the Co 3 O 4 lattice. The Ir L 3 -edge XANES spectrum ( Figure 3b ) of IrBa-Co 3 O 4 shows a white line peak shifted toward higher energies relative to Ir foil, approaching that of IrO 2 , indicating an Ir oxidation state close to +4. The increased white line intensity suggests a higher density of unoccupied d-states, which may enhance electrocatalytic activity. Extended X-ray absorption fine structure (EXAFS) analysis ( Figures 3c, d ) reveals that the bulk structure of IrBa-Co 3 O 4 remains largely unchanged after doping, though the Co oct –Co oct bond length slightly decreases, confirming compressive strain in the lattice. The Ir L-edge EXAFS spectrum (Figure 3d) exhibits a dominant Ir–O peak, with no evidence of Ir–Ir bonds, confirming the absence of Ir clusters/nanoparticles. A unique feature at R = 2.03 Å suggests the presence of Ir–O–Ba/Co bonds, distinct from the Ir–O scattering in IrO 2 (R = 1.98 Å). “‘latex Electrochemical OER performance of IrBa-Co 3 O 4 To evaluate the OER activity of IrBa-Co 3 O 4 , electrochemical measurements were conducted using a three-electrode setup in 0.5 M H 2 SO 4 electrolyte, with reference samples including Ir-Co 3 O 4 , Ba-Co 3 O 4 , and Co 3 O 4 . The linear sweep voltammetry (LSV) curves ( Figure 4a ) revealed that IrBa-Co 3 O 4 exhibited superior OER performance compared to the reference catalysts. Specifically, at a current density of 10 mA cm -2 , IrBa-Co 3 O 4 required an exceptionally low overpotential of 251 mV ( Figure 4a ), outperforming Ir-Co 3 O 4 (283 mV), Ba-Co 3 O 4 (449 mV), and Co 3 O 4 (471 mV) ( Figure 4b ). Even at a higher current density of 100 mA cm −2 , IrBa-Co 3 O 4 maintained excellent acidic OER activity with an overpotential of 389 mV ( Figure 4a ). The enhanced OER activity of Ir-Co 3 O 4 and IrBa-Co 3 O 4 can be attributed to the presence of Ir at the octahedral sites of the spinel Co 3 O 4 , confirming Ir as the primary active species for acidic OER. To further assess reaction kinetics, Tafel slopes were measured ( Figure 4c ). Among all catalysts, IrBa-Co 3 O 4 exhibited the lowest Tafel slope (65.28 mV dec -1 ), significantly lower than Ir-Co 3 O 4 (94.6 mV dec -1 ), Co 3 O 4 (212.8 mV dec -1 ), and Ba-Co 3 O 4 (245.5 mV dec -1 ). This indicates faster OER kinetics for IrBa-Co 3 O 4 , suggesting that Ir incorporation into the spinel structure not only enhances OER activity but also accelerates reaction kinetics. Moreover, electrochemical impedance spectroscopy (EIS) measurements at an overpotential of 0.2 V (Figure 4d) confirmed that IrBa-Co 3 O 4 had the lowest charge transfer resistance (Rct), further supporting its improved reaction kinetics. To evaluate intrinsic OER activity, current densities were normalized using electrochemical active surface area (ECSA, Figure 4e ), determined via double-layer capacitance (Cdl, Figure S5). The ECSA of IrBa-Co 3 O 4 (0.613 cm²) was significantly higher than that of Ir-Co 3 O 4 (0.531 cm²), Ba-Co 3 O 4 (0.266 cm²), and Co 3 O 4 (0.127 cm²). This confirms that IrBa-Co 3 O 4 possesses a greater number of active sites, confirming to its superior performance. The OER performance of IrBa-Co 3 O 4 exceeds that of most high-activity electrocatalysts reported previously (Table S2). Due to its outstanding OER activity, IrBa-Co 3 O 4 was employed as the anode in a two-electrode acidic water electrolysis setup, with Pt/C as the cathode ( Figure 4f ). The IrBa-Co 3 O 4 || Pt/C system demonstrated excellent performance, cell voltages of 1.57 V and 1.85 V are required to reach a current density of 10 mA cm -2 and 50 mA cm -2 , respectively. Chronoamperometry (CA) tests in 0.5 M H 2 SO 4 ( Figure 4g ) confirmed that IrBa-Co 3 O 4 || Pt/C maintained stable operation at 10 mA cm⁻² for 100 hours. Post-reaction characterization via SEM, XRD, and EDS mapping (Figures S6-S8) further validated the catalyst’s durability, where no crystal structure changes, morphological degradation, particle aggregation, or structural collapse can be found. Exploring the OER mechanism Identifying the structural changes during the OER is essential for elucidating its underlying mechanisms. To achieve this, we monitored the structural evolution of IrBa-Co 3 O 4 under acidic OER conditions (1.0-2.0 V) in real-time using in situ surface-enhanced Raman spectroscopy. As shown in Figure 5a , IrBa-Co 3 O 4 exhibited five Raman-active modes: A 1g , E g , and three F 2g modes, characteristic of its spinel structure. The A 1g mode corresponds to the stretching of Co 3+ -O bonds in octahedral CoO 6 (Co oct ), while the F 2g modes arise from Co 2+ -O bonds in tetrahedral CoO 4 (Co tet ). Notably, changes in the A 1g mode (685 cm -1 ) were more pronounced than those in the F 2g modes (195 cm⁻¹) ( Figure 5b ). This enhancement can be attributed to compressive strain induced by Ir and Ba co-doping. With increasing applied voltage, the A 1g peak shifted rightward, indicating compression and shortening of the Co oct -O bond, a phenomenon that may activate the DOM pathway and enhance catalytic activity in acid environments. In contrast, Ir-Co 3 O 4 and Ba-Co 3 O 4 exhibited leftward shifts in their A 1g modes (Figure S9), corresponding to bond elongation, which compromises catalyst stability under acid conditions. Thus, we conclude that IrBa-Co 3 O 4 exhibits superior activity and stability in acidic OER conditions due to Ir/Ba co-doping, which induces Co-O bond compression and shortening, consistent with XAS results. Conclusions This study successfully developed an Ir/Ba co-doped Co 3 O 4 (IrBa-Co 3 O 4 ) electrocatalyst with low Ir content (1.473 at. %) for efficient acidic OER. By leveraging Ba-induced compressive strain, we achieved atomic-level Ir dispersion, optimizing the geometric and electronic structure of active sites for exceptional catalytic performance and stability under harsh acidic conditions. Ba doping shortened Co-Co bond distances, stabilizing Ir sites against aggregation. Atomic-resolution STEM and EDS mapping confirmed uniform Ir/Ba dispersion. IrBa-Co 3 O 4 achieved a low overpotential of 251 mV at 10 mA cm -2 and >100 hours of stability in 0.5 M H 2 SO 4 . In situ Raman spectroscopy revealed that Co oct -O bond contraction under OER conditions stems from compressive strain due to co-doping of Ir and Ba, minimizing lattice oxygen loss. This work provides an efficient design strategy for advanced electrocatalysts in renewable hydrogen technologies. Experimental Chemicals and materials. Hexachloroiridic acid hexahydrate (H 2 IrCl 6 ·6H 2 O), barium nitrate(Ba(NO 3 ) 2 ·6H 2 O), Cobalt nitrate hexahydrate (Co(NO 3 ) 2 ·6H 2 O, ≥99%), concentrated sulfuric acid (H 2 SO 4 A.R.), and ethanol (C 2 H 5 OH, ≥99.7%) were purchased from Sinopharm Chemical Reagent Co., Ltd. All chemicals were used without further purification. Aqueous solutions were prepared using ultrapure water (18.2 MΩ·cm -1 ) obtained from a Millipore purification system. Synthesis of Co 3 O 4 Co 3 O 4 nanosheets on carbon cloth (CC) were synthesized via electrodeposition followed by calcination in air. In a typical synthesis, 3.6932 g Co(NO 3 ) 2 ·6H 2 O was dissolved in 250 mL of distilled water to prepare the plating solution. A piece of CC (1 cm × 2 cm), precleaned sequentially with acetone, distilled water, and ethanol (each for 10 min under ultrasonication), served as the working electrode, while a saturated calomel electrode (SCE) and a Pt sheet (1 cm × 2 cm) were used as the reference and counter electrodes, respectively. Electrodeposition was performed at -1.0 V vs. SCE for 30 min at ambient temperature. The CC with deposited Co(OH) 2 nanosheets was then rinsed several times with distilled water and calcined at 370 °C for 3 h in air at a heating rate of 5 °C min -1 . Synthesis of Ba-Co 3 O 4 A mixture of 3.6932 g Co(NO 3 ) 2 ·6H 2 O and 0.5626 g Ba(NO 3 ) 2 ·4H 2 O was dissolved in 250 mL distilled water to prepare the plating solution. The electrodeposition procedure followed the same steps for Co 3 O 4 synthesis. The resulting CC with deposited nanosheets was rinsed with distilled water and calcined at 370 °C for 3 h in air (heating rate: 5 °C min -1 ) to obtain Ba-Co 3 O 4 . Synthesis of Ir-Co 3 O 4 A piece of CC coated with Co 3 O 4 nanosheets was immersed into an aqueous Ir solution (12 mg in 20 mL) and maintained at 60 °C in an air oven for 9 h. After the reaction, the Ir-doped Co 3 O 4 was calcined at 250 °C for 3 h in air (heating rate: 5 °C min -1 ). Synthesis of IrBa-Co 3 O 4 A piece of CC coated with Ba-Co 3 O 4 nanosheets was immersed an aqueous Ir solution (12 mg in 20 mL) and kept at 60 °C in an air oven for 9 h. The Ir-doped Ba-Co 3 O 4 was then calcined at 250 °C for 3 h in air (heating rate: 5 °C min -1 ) to obtain IrBa-Co 3 O 4 . Physical characterization Scanning electron microscopy (SEM) images were acquired using an XL30 ESEM-FEG field-emission scanning electron microscope (FEI Co.) High-resolution transmission electron microscope (HR-TEM) characterizations were conducted on a JEOL JEM-2100F at 200 kV. Spherical aberration-corrected transmission electron microscope was conducted on JEM-ARM200F), which was equipped with energy-dispersive X-ray spectrum (EDS). Raman spectrum was performed on a JY HR-800 LabRam confocal Raman microscope (488 nm excitation, backscattering configuration). Inductively-coupled plasma optical emission spectroscopy (ICP-OES) was used for chemical composition analysis. X-ray diffraction (XRD) analysis was conducted on a D8 Focus diffractometer (Bruker) with Cu-Kα radiation (λ=0.15405 nm). X-ray photoelectron spectrum (XPS) was performed on an ECSALAB 250 using monochromatized Al-Kα radiation. Wettability analysis was measured using a contact angle goniometer (DSA 100, KRUSS). X-ray absorption (XAS) spectroscopy were conducted at the BL17W1 station of the Shanghai Synchrotron Radiation Facility. 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Figure 3 X-ray absorption spectroscopy analysis. (a) Co K-edge XANES spectra, (b) Ir L-edge XANES spectra for IrBa-Co 3 O 4 , Co 3 O 4 and Co foil. Fourier transforms (FTs) of (c) Co K-edge and (d) Ir L-edge EXAFS oscillations. “‘latex Figure 4 Electrocatalytic OER properties in 0.5 M H 2 SO 4 (pH = 0). (a) Linear sweep voltammetry (LSV) curves with a scanning rate of 5 mV s -1 , (b) Overpotentials at 10 mA cm -2 for different samples, (c) Tafel slopes of different samples, (d) Nyquist plots at 1.5 V vs. RHE of different samples, (e) Capacitive current density vs scan rate for IrBa-Co 3 O 4 , Co 3 O 4 , and Co foil, (f) LSV curves for overall water splitting, inset in (f) shows a schematic illustration of the two electrodes overall water splitting cell, (g) Chronoamperometry stability test at 1.57 V using IrBa-Co 3 O 4 || Pt/C catalysts. “‘latex Figure 5 In situ Raman spectra analysis. In situ Raman spectra of IrBa-Co 3 O 4 at region of (a) 100-1000 cm -1 and (b) enlarged areas under OER conditions. Left to Right: Mengtian Huo, Qianyu Li, Yu Liang, Wei Liu, Huiying Wang, Kaichi Qin, Xinran Sun, Yue Ma, Zihao Xing, Jinfa Chang Entry for the Table of Contents “‘latex A highly active and stable IrBa-Co 3 O 4 catalyst, engineered with compressive strain, was successfully synthesized for efficient oxygen evolution reaction in acidic media. Information & Authors Information Version history V1 Version 1 21 April 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords compressive strain iridium catalysts lattice contraction oxygen evolution reaction transition metal oxides Authors Affiliations Mengtian Huo Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Qianyu Li Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Yu Liang Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Wei Liu Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Huiying Wang Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Kaichi Qin Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Xinran Sun Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Yue Ma Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Zihao Xing Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Jinfa Chang 0000-0002-5066-3625 [email protected] Northeast Normal University Institute of Polyoxometalate Chemistry View all articles by this author Metrics & Citations Metrics Article Usage 311 views 206 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Mengtian Huo, Qianyu Li, Yu Liang, et al. 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