Regulating the amount of graphene oxide for enhanced capacitive energy storage of MOF derived materials

Regulating the amount of graphene oxide for enhanced capacitive energy storage of MOF derived materials | 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 Short Report Regulating the amount of graphene oxide for enhanced capacitive energy storage of MOF derived materials Yongji Qin, Jingquan Yang, Hao Wang, Meiling Lian, Peipei Jia, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5034230/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 27 Jul, 2025 Read the published version in Journal of Electrochemistry → Version 1 posted You are reading this latest preprint version Abstract In pursuit of more efficient and stable electrochemical energy storage materials, composite materials consisting of metal oxides and graphene oxide have garnered significant attention due to their unique structures and exceptional properties. Graphene oxide (GO), a two-dimensional material with an extremely high specific surface area and excellent conductivity, offers new possibilities for enhancing the electrochemical performance of metal oxides. In this work, we synthesized metal-organic framework (MOF) and GO composites with regulated amount of GO and successfully prepared composites of metal oxides supported by nitrogen-doped carbon frameworks and GO through a simple one-step calcination process. Through capacitive-property tests, the optimal amount of GO was figured out. This research will provide new insights and directions for designing and synthesizing metal oxide and graphene oxide composite materials with ideal electrochemical performance. MOF Fe3O4 graphene oxide composite material supercapacitor pseudocapacitor energy storage Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction The energy crisis and environmental issues have become increasingly severe, posing significant challenges to sustainable global development [ 1 – 4 ] . It is urgent to explore green and efficient energy solutions, including fuel cells [ 5 – 7 ] , metal batteries [ 8 – 10 ] , overall water splitting devices [ 11 – 14 ] , and supercapacitors (SCs) [ 15 ] , in order to achieve balance between economic development and environmental protection. Among various candidates, SCs have attracted widespread interest due to their high-power densities, rapid charge/discharge capabilities, long cyclic life and wide working range [ 16 ] . Electrochemical double-layer capacitors (EDLCs) which store energy through ion adsorption and desorption, and pseudocapacitors based on redox reactions are the two major types of supercapacitors [ 17 ] . Due to their different energy storage mechanism, the pseudocapacitors display higher energy densities and lower power densities than EDLCs [ 18 ] . Notably, the combination of these two capacitors is considered as an ideal strategy to obtain advanced SCs, which can exhibit both high energy and power densities [ 18 ] . However, it remains challenging to synthesize hybrid SCs with favorable performances. Metal-organic frameworks (MOFs) are a kind of periodic porous materials which assembled through coordination bonds between metal atoms and organic ligands [ 19 – 22 ] . The diverse compositions and morphologies render MOFs as promising precursors with flexible tunability [ 23 ] . Consequently, MOFs derived materials, such as carbon-based materials, metal oxides, metal hydroxides, metal phosphides, metal sulfides and other complex materials, have shown appealing performances towards energy conversion and storage [ 24 – 29 ] . Among various candidates, metal oxides have shown promise due to their high theoretical capacitance and abundant redox reactions [ 30 ] . However, their practical applications are often limited by poor conductivity and structural instability during charge-discharge cycles. Graphene oxide (GO), a derivative of graphene, which is a monolayer two-dimensional material composed of honeycomb-arranged C atoms, is obtained through the oxidation and exfoliation of graphite [ 31 ] . The oxygen-containing functional groups on the surface of graphene oxide make it an ideal substrate for in situ growth of active materials, which could endow the composite materials with excellent conductivity and enhanced mechanical stability [ 32 ] . Typically, both the composite materials formed by coupling MOF with GO [ 33 ] , as well as their derivatives [ 34 ] , are one of the hybrid SCs and have demonstrated excellent performance in supercapacitor applications. However, the optimal ratio between pseudocapacitors and EDLCs is not explicit. In this study, Fe 3 O 4 nano particles supported by nitrogen-doped carbon frameworks and GO (FONP-NCG) were synthesized through a facile calcination process of MOF/GO composites with various GO adding amounts. The morphology and structure of FONP-NCG were characterized. Through electrochemical tests, the optimal ratio between MOF and GO was determined that yields the best electrochemical performance. Our findings provide valuable insights into the design and synthesis of hybrid SCs for advanced electrochemical energy storage applications. 2. Results and discussion The design and synthesis strategy for FONP-NCG is illustrated in Fig. 1 . Fe-MOF-NH 2 /GO composites are obtained by adding GO into the growth solution of MOF precursors. Fe-MOF-NH 2 is directly grown on GO through the oxygen-containing groups on the surfaces of GO. After calcination, the FONP-NCG composite material was obtained. The performance of the final product can be regulated by adding different amount of GO during the synthetic process. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were utilized to figure out the morphologies and sizes of the as-prepared samples. As shown in Figure S1 a, the SEM image of pristine Fe-MOF-NH 2 displayed a hexagonal prism-shaped morphology with with an average size around 1 µm. As the amount of GO added increases, the Fe-MOF-NH 2 prisms are gradually wrapped (Figure S1 b-d). Obviously, the sufficient amount of GO could hinder the exposure of active cites although it could endow the composite materials with excellent electrical conductivity. The TEM image of Fe-MOF-NH 2 /GO was shown in Fig. 2 a, demonstrating that MOFs are homogeneously distributed on the surface of GO and the presence of GO has no significant effect to the morphology and size of Fe-MOF-NH 2 . After calcination at nitrogen atmosphere, the MOF/GO composite material is converted into a composite of Fe 3 O 4 nano particles supported by nitrogen-doped carbon frameworks and GO (Fig. 2 b. S2). The carbon frameworks retain the hexagonal prism-shaped morphology of the parent MOF. Part of the iron particles are confined within the carbon frameworks with a size around of 50 nm, and part of the iron particles are agglomerated on the graphene sheets with larger sizes. Powder X-ray diffraction (XRD) tests were carried out to characterize the crystal structures of the as-prepared samples. The XRD pattern of Fe-MOF-NH 2 /GO is similar to that of the pristine Fe-MOF-NH 2 (Figure S3), indicating the addition of GO into the growth solution of MOF precursors has no noteworthy influence of the crystal structure of MOF, which is consistent with the results of SEM and TEM. As shown in Figure S4, the XRD patterns of FONP-NC (derived from pristine Fe-MOF-NH 2 ) and FONP-NCG display several sharp peaks, which correspond to that of Fe 3 O 4 (PDF#19–0629), verifying the formation of Fe 3 O 4 nano particles. Moreover, the Fe weight ratios of FONP-NC and FONP-NCG are 55.5 and 13.5 wt%, which are determined by inductively coupled plasma (ICP) tests (Figure S5). Therefore, the ratio of pseudocapacitors and EDLCs can be regulated by adding different amount of GO into the precursors. High-resolution (HR) TEM images of FONP-NCG show that the crystal plane spacing of nanoparticles in the composite material is 0.25 nm, which is consistent with the (311) crystal plane in the standard data of Fe 3 O 4 (PDF#19–0629). The white circles in Fig. 2 d indicate the presence of graphene in the calcined product, demonstrating the successful fabrication of composite materials. The X-ray photoelectron spectroscopy (XPS) test was performed to gain a further understanding of the chemical composition and valence states of the FONP-NCG. The XPS survey spectra of FONP-NCG verifies the existence of Fe, O, N, and C elements (Figure S6). The HR-XPS spectra of Fe 2 p could be deconvolved into five peaks, including two peaks at around 729 and 713 eV for Fe 3+ , two peaks at around 724 and 710 eV for Fe 2+ , and one peak at around 717 eV for satellite peak (Fig. 3 a) [ 35 ] , which is consistent with the XRD result in Figure S4. The HR-XPS spectra of O 1 s can be fitted into three peaks at 533.4, 531.7 and 530.3 eV, corresponding to absorbed water molecules, oxygen vacancies (OVs) and Fe-O bonds, respectively (Fig. 3 b) [ 36 ] . The presence of OVs ccould offer significantly improvement of the electrochemical performance. There are three peaks located at around 405 eV for oxidized N, 400.6 eV for graphitic N and 398.6 eV for pyridinic N, appearing in the HR-XPS spectra of N 1 s (Fig. 3 c) [ 37 ] . The doping of N could regulate the electronic structure and facilitate the electron transfer. The HR-XPS spectra of C 1 s displays four peaks, ascribed to -COO at around 290 eV, O-C at 288.1 eV, N-C at 285.7 eV and C-C at 284.8 eV [ 38 ] , demonstrating the successful doping of N element, and chemical bonding between Fe 3 O 4 NPs and carbon matrix. All the above results confirm the successful fabrication of FONP-NCG. The successful fabrication of FONP-NCG gives us an opportunity to evaluate its electrochemical performance towards capacitive energy storage. The electrochemical tests were measured by using a typical three-electrode system with carbon rod as counter electrode as well as standard calomel electrode (SCE) as reference electrode in 6 M KOH aqueous solution. For convenience, the samples are also denoted as GO-0, which is the FONP-NC without adding GO into the growth solution, and GO-1 to GO-7.5, which are a series of FONP-NCG composites prepared with adding various amounts of GO solution from 1 to 7.5 mL into the MOF precursors solution. The charge-discharge curves of the as-prepared samples tested at a constant current density of 0.5 A g − 1 are shown in Fig. 4 a. According to the results, the GO-2.5 exhibits a capacitance of 342 F g − 1 , which is much larger than those of GO-0 (157.5 F g − 1 ), GO-1 (234 F g − 1 ), GO-5 (266 F g − 1 ) and GO-7.5 (225.5 F g − 1 ). When the constant current density increases from 0.5 A g − 1 to 1, 2 and 5 A g − 1 , the GO-2.5 (FONP-NCG) still demonstrates better performance than other samples (Figure S7). The electrochemical impedance spectroscopy (EIS) was carried out to gain a better understanding of the reaction kinetics on the electrode surface. The solution resistance (R S ) can be directly obtained through the intersection point of the EIS data and horizontal axis [ 39 ] . According to the EIS data shown in Fig. 4 b, the GO-2.5 shows a much smaller R S than other samples, indicating a better electro transfer capability and faster reaction kinetics. The EIS results are consistent with charge-discharge tests, indicating that the optimal adding amount of GO is 2.5 mL of the as-prepared GO solution. The charge-discharge curves of GO-2.5 at constant current densities of 0.5, 1, 2, and 5 A g − 1 are shown in Fig. 4 c. The capacitive values of GO-2.5 are 342, 318, 295, and 268 F g − 1 at constant current densities of 0.5, 1, 2, and 5 A g − 1 , respectively. After increasing the constant current density from 0.5 to 5 A g − 1 , the capacitance retains 78%. The cyclic voltammetry (CV) curves of GO-2.5 were recorded at the scan rates of 5, 10, 20, 50, 100, 200 mV s − 1 in 6 M KOH solution (Figure S8). The CV curve does not have a perfect symmetric rectangular shape due to the presence of Fe 3 O 4 with pseudocapacitive properties, resulting in redox peaks. Additionally, the electron transfer kinetics of the electrode material and the limited ion adsorption/desorption rate on the surface of the electrode material also affect the shape of the CV curve. Stability test was conducted at a constant current density of 5 A g − 1 . After 1700 charge-discharge cycles, the FONP-NCG still retains about 75% of its capacitance, demonstrating an excellent stability. 3. Conclusions We have synthesized a series of MOF/GO composite materials with different amount of GO and obtained composite materials of metal oxides supported by nitrogen-doped carbon frameworks and graphene through a simple one-step calcination process. Through electrochemical testing, we have identified the sample with optimal performance and explored the best amount of GO. We believe that our work can provide ideas for the design of synthesizing metal oxide and graphene composite materials to achieve even better electrochemical performance. Declarations Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Contribution J. Liu and Y. Qin designed the project; Y. Qin performed the experiments; J. Yang, M. Lian and P. Jia co-analyzed data; Y. Qin and H. Wang co-wrote the manuscript; J. Luo and X. Liu revised the manuscript. All the authors discussed and commented on the data and contributed to the manuscript. Acknowledgements This work was financially supported by the National Natural Science Foundation of China (51971157), Shenzhen Science and Technology Program (JCYJ20210324115412035, JCYJ20210324123202008, JCYJ20210324122803009 and ZDSYS20210813095534001), Guangdong Foundation for Basic and Applied Basic Research Program (2021A1515110880). References Quan L, Jiang H, Mei G, Sun Y, You B. Bifunctional Electrocatalysts for Overall and Hybrid Water Splitting[J]. Chem. Rev., 2024, 124(7): 3694-3812. Yao W, Liao K, Lai T, Sul H, Manthiram A. Rechargeable Metal-Sulfur Batteries: Key Materials to Mechanisms[J]. Chem. Rev., 2024, 124(8): 4935-5118. Lu G, Hou X, Ding J, Qin Y, Luo J, Liu X. Research progress in electrocatalytic reduction of nitrate to ammonia by copper-based materials[J]. Chin. Sci. Bull., 2024: doi: 10.1360/TB-2023-1349. Ji Y, Yu Z, Yan L, Song W. Research progress in preparation, modification and application of biomass-based single-atom catalysts[J]. China Powder Sci. 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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-5034230","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":365473176,"identity":"86410aa9-9785-453b-a103-913eb720c6ce","order_by":0,"name":"Yongji Qin","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAtklEQVRIiWNgGAWjYHCCxAcwlgSxWpINYKqJ1sImQZoWvhsJz6p5Kurq+BuYD97mYbDLI6hF8kZC2m2eM4clJA6wJVvzMCQXE9RiANLC23ZAwoCBx0yah+FAYgMxWop5/9UBtfB/I14LM28DM8gWNuK0SJ55kCw559hhyRmH2Ywt5xgkE9bCdzwn8cObmjp+/vbmhzfeVNgR1sJwIScBwmAGu5OgeiA4f/wAMcpGwSgYBaNgJAMAnVo4KPB4QMsAAAAASUVORK5CYII=","orcid":"","institution":"University of Electronic Science and Technology of China","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Yongji","middleName":"","lastName":"Qin","suffix":""},{"id":365473177,"identity":"9425f864-cd5d-4b21-a5d2-b81b7c33c7e0","order_by":1,"name":"Jingquan Yang","email":"","orcid":"","institution":"University of Electronic Science and Technology of China","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jingquan","middleName":"","lastName":"Yang","suffix":""},{"id":365473178,"identity":"c4bb7f5f-b6b6-4143-b0c6-025d88dbdcb1","order_by":2,"name":"Hao Wang","email":"","orcid":"","institution":"China National Coal Group Corporation","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hao","middleName":"","lastName":"Wang","suffix":""},{"id":365473179,"identity":"d9ab2483-9f7d-4a74-ac7d-bfd1b1a1919f","order_by":3,"name":"Meiling Lian","email":"","orcid":"","institution":"Civil Aviation University of China","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Meiling","middleName":"","lastName":"Lian","suffix":""},{"id":365473180,"identity":"004ecb11-72ee-43a6-8153-6e65a8033838","order_by":4,"name":"Peipei Jia","email":"","orcid":"","institution":"University of Electronic Science and Technology of China","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Peipei","middleName":"","lastName":"Jia","suffix":""},{"id":365473181,"identity":"aaa2747f-4505-4fb6-ac54-d0b29b8fa243","order_by":5,"name":"Jun Luo","email":"","orcid":"","institution":"University of Electronic Science and Technology of China","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jun","middleName":"","lastName":"Luo","suffix":""},{"id":365473182,"identity":"69523272-76e7-47de-a011-95953e2dae8a","order_by":6,"name":"Xijun Liu","email":"","orcid":"","institution":"Guangxi University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Xijun","middleName":"","lastName":"Liu","suffix":""},{"id":365473183,"identity":"a238fc6d-51a0-406c-a386-f8908061b182","order_by":7,"name":"Junfeng Liu","email":"","orcid":"","institution":"Beijing University of Chemical Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Junfeng","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2024-09-05 00:08:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5034230/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5034230/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.61558/2993-074X.3548","type":"published","date":"2025-07-28T00:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":66741766,"identity":"2019db82-0134-44cf-bf02-04bf1ec433a3","added_by":"auto","created_at":"2024-10-16 05:57:08","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1337296,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic illustration for the fabrication of FONP-NCG.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5034230/v1/0cf8eaa4fe2b1a9abe2d21f2.png"},{"id":66741768,"identity":"efbb540e-cf77-4dc3-95e5-42c3c9d6060a","added_by":"auto","created_at":"2024-10-16 05:57:08","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2010338,"visible":true,"origin":"","legend":"\u003cp\u003eTEM images of (a) Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e/GO and (b) FONP-NCG. HR-TEM images of (c, d) FONP-NCG.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5034230/v1/1b65d0fa6754e0133e3223e9.png"},{"id":66741764,"identity":"4d6f8557-0985-4b44-bb67-5c75d1ca1469","added_by":"auto","created_at":"2024-10-16 05:57:08","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1030316,"visible":true,"origin":"","legend":"\u003cp\u003eHR-XPS spectrum of (a) Fe 2\u003cem\u003ep\u003c/em\u003e, (b) O 1\u003cem\u003es\u003c/em\u003e, (c) N 1\u003cem\u003es\u003c/em\u003e and (d) C 1\u003cem\u003es\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5034230/v1/f6869af72b1e3c479f8b93c8.png"},{"id":66741767,"identity":"769e1b34-583d-47ba-b650-0bdd0ec48241","added_by":"auto","created_at":"2024-10-16 05:57:08","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":742640,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Charge/discharge curves of FONP-NCG with various adding amount of GO at 0.5 A\u003csup\u003e.\u003c/sup\u003eg\u003csup\u003e-1\u003c/sup\u003e. (b) EIS spectrum of the as-prepared samples. (c) Charge/discharge curves of FONP-NCG at various current densities. (d) Cycling stability of FONP-NCG composite at a current density of 5 A g\u003csup\u003e-1\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5034230/v1/c503d48bedb6f8498c4b81cd.png"},{"id":87768820,"identity":"d12abcbf-9384-4b34-a0c4-397ea8857ed5","added_by":"auto","created_at":"2025-07-28 18:56:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6391722,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5034230/v1/0ed95971-602b-46d6-96bb-e2db72a9ab0a.pdf"},{"id":66741765,"identity":"6e52aa48-ded5-47c4-8b1e-a3c32fb1574e","added_by":"auto","created_at":"2024-10-16 05:57:08","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1238203,"visible":true,"origin":"","legend":"","description":"","filename":"supportinginformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-5034230/v1/21551defddc486482cdb8568.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Regulating the amount of graphene oxide for enhanced capacitive energy storage of MOF derived materials","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe energy crisis and environmental issues have become increasingly severe, posing significant challenges to sustainable global development\u003csup\u003e[\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. It is urgent to explore green and efficient energy solutions, including fuel cells\u003csup\u003e[\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e, metal batteries\u003csup\u003e[\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e, overall water splitting devices\u003csup\u003e[\u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e, and supercapacitors (SCs)\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e, in order to achieve balance between economic development and environmental protection. Among various candidates, SCs have attracted widespread interest due to their high-power densities, rapid charge/discharge capabilities, long cyclic life and wide working range\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. Electrochemical double-layer capacitors (EDLCs) which store energy through ion adsorption and desorption, and pseudocapacitors based on redox reactions are the two major types of supercapacitors\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. Due to their different energy storage mechanism, the pseudocapacitors display higher energy densities and lower power densities than EDLCs\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. Notably, the combination of these two capacitors is considered as an ideal strategy to obtain advanced SCs, which can exhibit both high energy and power densities\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. However, it remains challenging to synthesize hybrid SCs with favorable performances.\u003c/p\u003e \u003cp\u003eMetal-organic frameworks (MOFs) are a kind of periodic porous materials which assembled through coordination bonds between metal atoms and organic ligands\u003csup\u003e[\u003cspan additionalcitationids=\"CR20 CR21\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. The diverse compositions and morphologies render MOFs as promising precursors with flexible tunability\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. Consequently, MOFs derived materials, such as carbon-based materials, metal oxides, metal hydroxides, metal phosphides, metal sulfides and other complex materials, have shown appealing performances towards energy conversion and storage\u003csup\u003e[\u003cspan additionalcitationids=\"CR25 CR26 CR27 CR28\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e. Among various candidates, metal oxides have shown promise due to their high theoretical capacitance and abundant redox reactions\u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. However, their practical applications are often limited by poor conductivity and structural instability during charge-discharge cycles.\u003c/p\u003e \u003cp\u003eGraphene oxide (GO), a derivative of graphene, which is a monolayer two-dimensional material composed of honeycomb-arranged C atoms, is obtained through the oxidation and exfoliation of graphite\u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e. The oxygen-containing functional groups on the surface of graphene oxide make it an ideal substrate for \u003cem\u003ein situ\u003c/em\u003e growth of active materials, which could endow the composite materials with excellent conductivity and enhanced mechanical stability\u003csup\u003e[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e. Typically, both the composite materials formed by coupling MOF with GO\u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e, as well as their derivatives\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e, are one of the hybrid SCs and have demonstrated excellent performance in supercapacitor applications. However, the optimal ratio between pseudocapacitors and EDLCs is not explicit.\u003c/p\u003e \u003cp\u003eIn this study, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nano particles supported by nitrogen-doped carbon frameworks and GO (FONP-NCG) were synthesized through a facile calcination process of MOF/GO composites with various GO adding amounts. The morphology and structure of FONP-NCG were characterized. Through electrochemical tests, the optimal ratio between MOF and GO was determined that yields the best electrochemical performance. Our findings provide valuable insights into the design and synthesis of hybrid SCs for advanced electrochemical energy storage applications.\u003c/p\u003e"},{"header":"2. Results and discussion","content":"\u003cp\u003eThe design and synthesis strategy for FONP-NCG is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e/GO composites are obtained by adding GO into the growth solution of MOF precursors. Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e is directly grown on GO through the oxygen-containing groups on the surfaces of GO. After calcination, the FONP-NCG composite material was obtained. The performance of the final product can be regulated by adding different amount of GO during the synthetic process.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eScanning electron microscope (SEM) and transmission electron microscope (TEM) were utilized to figure out the morphologies and sizes of the as-prepared samples. As shown in Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003ea, the SEM image of pristine Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e displayed a hexagonal prism-shaped morphology with with an average size around 1 \u0026micro;m. As the amount of GO added increases, the Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e prisms are gradually wrapped (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003eb-d). Obviously, the sufficient amount of GO could hinder the exposure of active cites although it could endow the composite materials with excellent electrical conductivity. The TEM image of Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e/GO was shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, demonstrating that MOFs are homogeneously distributed on the surface of GO and the presence of GO has no significant effect to the morphology and size of Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003eAfter calcination at nitrogen atmosphere, the MOF/GO composite material is converted into a composite of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nano particles supported by nitrogen-doped carbon frameworks and GO (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb. S2). The carbon frameworks retain the hexagonal prism-shaped morphology of the parent MOF. Part of the iron particles are confined within the carbon frameworks with a size around of 50 nm, and part of the iron particles are agglomerated on the graphene sheets with larger sizes.\u003c/p\u003e \u003cp\u003ePowder X-ray diffraction (XRD) tests were carried out to characterize the crystal structures of the as-prepared samples. The XRD pattern of Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e/GO is similar to that of the pristine Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e (Figure S3), indicating the addition of GO into the growth solution of MOF precursors has no noteworthy influence of the crystal structure of MOF, which is consistent with the results of SEM and TEM. As shown in Figure S4, the XRD patterns of FONP-NC (derived from pristine Fe-MOF-NH\u003csub\u003e2\u003c/sub\u003e) and FONP-NCG display several sharp peaks, which correspond to that of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (PDF#19\u0026ndash;0629), verifying the formation of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nano particles. Moreover, the Fe weight ratios of FONP-NC and FONP-NCG are 55.5 and 13.5 wt%, which are determined by inductively coupled plasma (ICP) tests (Figure S5). Therefore, the ratio of pseudocapacitors and EDLCs can be regulated by adding different amount of GO into the precursors.\u003c/p\u003e \u003cp\u003eHigh-resolution (HR) TEM images of FONP-NCG show that the crystal plane spacing of nanoparticles in the composite material is 0.25 nm, which is consistent with the (311) crystal plane in the standard data of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (PDF#19\u0026ndash;0629). The white circles in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed indicate the presence of graphene in the calcined product, demonstrating the successful fabrication of composite materials.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe X-ray photoelectron spectroscopy (XPS) test was performed to gain a further understanding of the chemical composition and valence states of the FONP-NCG. The XPS survey spectra of FONP-NCG verifies the existence of Fe, O, N, and C elements (Figure S6).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe HR-XPS spectra of Fe 2\u003cem\u003ep\u003c/em\u003e could be deconvolved into five peaks, including two peaks at around 729 and 713 eV for Fe\u003csup\u003e3+\u003c/sup\u003e, two peaks at around 724 and 710 eV for Fe\u003csup\u003e2+\u003c/sup\u003e, and one peak at around 717 eV for satellite peak (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea)\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e, which is consistent with the XRD result in Figure S4. The HR-XPS spectra of O 1\u003cem\u003es\u003c/em\u003e can be fitted into three peaks at 533.4, 531.7 and 530.3 eV, corresponding to absorbed water molecules, oxygen vacancies (OVs) and Fe-O bonds, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb)\u003csup\u003e[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/sup\u003e. The presence of OVs ccould offer significantly improvement of the electrochemical performance. There are three peaks located at around 405 eV for oxidized N, 400.6 eV for graphitic N and 398.6 eV for pyridinic N, appearing in the HR-XPS spectra of N 1\u003cem\u003es\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec)\u003csup\u003e[\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/sup\u003e. The doping of N could regulate the electronic structure and facilitate the electron transfer. The HR-XPS spectra of C 1\u003cem\u003es\u003c/em\u003e displays four peaks, ascribed to -COO at around 290 eV, O-C at 288.1 eV, N-C at 285.7 eV and C-C at 284.8 eV\u003csup\u003e[\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e, demonstrating the successful doping of N element, and chemical bonding between Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e NPs and carbon matrix. All the above results confirm the successful fabrication of FONP-NCG.\u003c/p\u003e \u003cp\u003eThe successful fabrication of FONP-NCG gives us an opportunity to evaluate its electrochemical performance towards capacitive energy storage. The electrochemical tests were measured by using a typical three-electrode system with carbon rod as counter electrode as well as standard calomel electrode (SCE) as reference electrode in 6 M KOH aqueous solution. For convenience, the samples are also denoted as GO-0, which is the FONP-NC without adding GO into the growth solution, and GO-1 to GO-7.5, which are a series of FONP-NCG composites prepared with adding various amounts of GO solution from 1 to 7.5 mL into the MOF precursors solution.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe charge-discharge curves of the as-prepared samples tested at a constant current density of 0.5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea. According to the results, the GO-2.5 exhibits a capacitance of 342 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which is much larger than those of GO-0 (157.5 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), GO-1 (234 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), GO-5 (266 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and GO-7.5 (225.5 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). When the constant current density increases from 0.5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 1, 2 and 5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the GO-2.5 (FONP-NCG) still demonstrates better performance than other samples (Figure S7).\u003c/p\u003e \u003cp\u003eThe electrochemical impedance spectroscopy (EIS) was carried out to gain a better understanding of the reaction kinetics on the electrode surface. The solution resistance (R\u003csub\u003eS\u003c/sub\u003e) can be directly obtained through the intersection point of the EIS data and horizontal axis\u003csup\u003e[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/sup\u003e. According to the EIS data shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, the GO-2.5 shows a much smaller R\u003csub\u003eS\u003c/sub\u003e than other samples, indicating a better electro transfer capability and faster reaction kinetics. The EIS results are consistent with charge-discharge tests, indicating that the optimal adding amount of GO is 2.5 mL of the as-prepared GO solution.\u003c/p\u003e \u003cp\u003eThe charge-discharge curves of GO-2.5 at constant current densities of 0.5, 1, 2, and 5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec. The capacitive values of GO-2.5 are 342, 318, 295, and 268 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at constant current densities of 0.5, 1, 2, and 5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. After increasing the constant current density from 0.5 to 5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the capacitance retains 78%. The cyclic voltammetry (CV) curves of GO-2.5 were recorded at the scan rates of 5, 10, 20, 50, 100, 200 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in 6 M KOH solution (Figure S8). The CV curve does not have a perfect symmetric rectangular shape due to the presence of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e with pseudocapacitive properties, resulting in redox peaks. Additionally, the electron transfer kinetics of the electrode material and the limited ion adsorption/desorption rate on the surface of the electrode material also affect the shape of the CV curve. Stability test was conducted at a constant current density of 5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. After 1700 charge-discharge cycles, the FONP-NCG still retains about 75% of its capacitance, demonstrating an excellent stability.\u003c/p\u003e"},{"header":"3. Conclusions","content":"\u003cp\u003eWe have synthesized a series of MOF/GO composite materials with different amount of GO and obtained composite materials of metal oxides supported by nitrogen-doped carbon frameworks and graphene through a simple one-step calcination process. Through electrochemical testing, we have identified the sample with optimal performance and explored the best amount of GO. We believe that our work can provide ideas for the design of synthesizing metal oxide and graphene composite materials to achieve even better electrochemical performance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDeclaration of Competing Interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ. Liu and Y. Qin designed the project; Y. Qin performed the experiments; J. Yang, M. Lian and P. Jia co-analyzed data; Y. Qin and H. Wang co-wrote the manuscript; J. Luo and X. Liu revised the manuscript. All the authors discussed and commented on the data and contributed to the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThis work was financially supported by the National Natural Science Foundation of China (51971157), Shenzhen Science and Technology Program (JCYJ20210324115412035, JCYJ20210324123202008, JCYJ20210324122803009 and ZDSYS20210813095534001), Guangdong Foundation for Basic and Applied Basic Research Program (2021A1515110880).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eQuan L, Jiang H, Mei G, Sun Y, You B. Bifunctional Electrocatalysts for Overall and Hybrid Water Splitting[J]. Chem. Rev., 2024, 124(7): 3694-3812.\u003c/li\u003e\n \u003cli\u003eYao W, Liao K, Lai T, Sul H, Manthiram A. Rechargeable Metal-Sulfur Batteries: Key Materials to Mechanisms[J]. Chem. Rev., 2024, 124(8): 4935-5118.\u003c/li\u003e\n \u003cli\u003eLu G, Hou X, Ding J, Qin Y, Luo J, Liu X. 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Energy Mater., 2022, 5(8): 9487-9494.\u003c/li\u003e\n\u003c/ol\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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"MOF, Fe3O4, graphene oxide, composite material, supercapacitor, pseudocapacitor, energy storage","lastPublishedDoi":"10.21203/rs.3.rs-5034230/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5034230/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn pursuit of more efficient and stable electrochemical energy storage materials, composite materials consisting of metal oxides and graphene oxide have garnered significant attention due to their unique structures and exceptional properties. Graphene oxide (GO), a two-dimensional material with an extremely high specific surface area and excellent conductivity, offers new possibilities for enhancing the electrochemical performance of metal oxides. In this work, we synthesized metal-organic framework (MOF) and GO composites with regulated amount of GO and successfully prepared composites of metal oxides supported by nitrogen-doped carbon frameworks and GO through a simple one-step calcination process. Through capacitive-property tests, the optimal amount of GO was figured out. This research will provide new insights and directions for designing and synthesizing metal oxide and graphene oxide composite materials with ideal electrochemical performance.\u003c/p\u003e","manuscriptTitle":"Regulating the amount of graphene oxide for enhanced capacitive energy storage of MOF derived materials","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-16 05:57:03","doi":"10.21203/rs.3.rs-5034230/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f4cafd91-47c9-4c99-a524-0fcce3ff6cc7","owner":[],"postedDate":"October 16th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-07-28T18:56:33+00:00","versionOfRecord":{"articleIdentity":"rs-5034230","link":"https://doi.org/10.61558/2993-074X.3548","journal":{"identity":"journal-of-electrochemistry","isVorOnly":true,"title":"Journal of Electrochemistry"},"publishedOn":"2025-07-28 00:00:00","publishedOnDateReadable":"July 28th, 2025"},"versionCreatedAt":"2024-10-16 05:57:03","video":"","vorDoi":"10.61558/2993-074X.3548","vorDoiUrl":"https://doi.org/10.61558/2993-074X.3548","workflowStages":[]},"version":"v1","identity":"rs-5034230","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5034230","identity":"rs-5034230","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}