English

• Hydrogen production via water electrolysis is widely recognized as a key technology for renewable energy utilization and carbon neutrality. However, achieving efficient and scalable hydrogen generation remains a major research focus, particularly in developing robust and low-cost electrode materials [1-6]. Among the two half-reactions involved, the oxygen evolution reaction (OER) at the anode is particularly critical, as its high overpotential and sluggish kinetics dominate the overall energy consumption of electrolysis [7-10]. Currently, noble metal-based catalysts (e.g., IrO₂ and RuO₂) exhibit excellent OER activity [11-13], but their scarcity and high cost hinder large-scale industrial adoption [14]. Therefore, developing low-cost, highly efficient, and durable OER anodes is essential for advancing green hydrogen production.

  Nickel (Ni) and its derivatives have attracted considerable attention as promising anode materials for the OER in water electrolysis, owing to their natural abundance and excellent electrochemical stability [15-17], and the ability to tailor their catalytic properties through various engineering techniques [18-20]. Over the past decade, substantial progress has been made in improving the OER performance of Ni-based catalysts using methods such as electrodeposition [21], hydrothermal synthesis [22,23], and template-assisted nanostructuring [24]. These approaches have demonstrated considerable success in enhancing catalytic activity by controlling the morphology, composition, and nanostructure of Ni catalysts, thus increasing their electrochemical efficiency [25-27].

  However, despite these advancements, many Ni-based catalysts fabricated by these high-activity strategies face several limitations that hinder their widespread use in industrial-scale electrolysis [28]. Firstly, these methods often require high energy input, lengthy processing times, or multi-step procedures, which increase the overall fabrication cost and make them less suitable for large-scale production [29]. Furthermore, while the methods can enhance the catalytic performance in small-scale or laboratory settings, their scalability remains a significant challenge [30]. The complexities associated with large-area uniformity and substrate compatibility reduce the effectiveness of these catalysts when applied to industrial systems where high throughput and durability are essential.

  To overcome these challenges, our work introduces a novel room-temperature strategy (surface functionalization) for the scalable fabrication of nickel-based anodes, donated as surface functionalization Ni mesh (SFN/NM). This approach leverages the intrinsic properties of nickel mesh (NM) substrates to rapidly (within 3 min) surface function a self-supporting, highly active electrode in a pure-water system, entirely free of high-temperature treatments or complex post-processing. By optimizing the material structure through surface functionalization process, we achieve uniform active site distribution, enhanced electrocatalytic activity, and long-term durability. The resulting electrodes exhibit outstanding performance in alkaline electrolyte, demonstrating a current density of 100 mA/cm² at a low overpotential of 300 mV and maintaining stable operation over 1600 h. Notably, the performance of these anodes rival that of commercial Raney nickel electrodes while reducing the production cost by approximately 50%−70%. This approach not only simplifies the fabrication process but also paves the way for the cost-effective production of large-area, high-performance OER electrodes for industrial water splitting applications.

  The electrode was prepared via a rapid, energy-free surface functionalization process at room temperature (25 ℃, 1 atm). Specifically, a commercially available NM was immersed in an aqueous surface functionalization solution containing sodium thiosulfate (Na₂S₂O₃) and ferric chloride (FeCl₃) for just 3 min. As illuminated in Fig. 1, the spontaneous surface reconstruction originates from a nickel-driven redox process: metallic Ni (Ni⁰) acts as the reducing agent to reduce Fe³⁺ to Fe²⁺ (Ni⁰ + 2Fe³⁺ → Ni²⁺ + 2Fe²⁺), while S₂O₃²⁻ ions accelerate this reaction by (1) complexing with Ni²⁺ to destabilize the Ni lattice ([Ni²⁺ + S₂O₃²⁻ → Ni(S₂O₃)_n]²⁻), and (2) serving as electron mediators to facilitate interfacial charge transfer. This synergistic dissolution-reconstruction mechanism generates hierarchical nanosheets architecture. This one-step, solution-based strategy enables large-area, scalable fabrication of OER-active electrodes without the need for external energy input, high-temperature treatment, or complex post-processing.

  Figure 1

  

  Figure 1.  Schematic illustration of the synthesis of SNM/NM electrode via surface functionalization at room temperature aqueous solution with Fe³⁺ and S₂O₃²⁻ ions for only 3 min.

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  As shown in Fig. 2a, the as-prepared SFN/NM electrode retains the intrinsic structural and material characteristics of the original nickel mesh substrate, ensuring mechanical robustness and electrical conductivity. The X-ray diffraction (XRD) pattern (Fig. S1 in Supporting information) further confirms the preservation of metallic Ni, as evidenced by the presence of well-defined diffraction peaks corresponding to the (111), (200), and (220) planes of face-centered cubic (fcc) nickel, with no detectable crystalline structures introduced during the functionalization process. To gain insight into the surface morphology, scanning electron microscopy (SEM) was employed. As depicted in Fig. 2b, the electrode surface is uniformly covered with vertically aligned, densely packed nanosheets, forming a hierarchical nanostructure that is beneficial for exposing abundant electrochemically active sites and facilitating mass transport during the OER. The sheet-like structure is further verified by transmission electron microscopy (TEM), as shown in Fig. 2c, where thin, transparent nanoflakes with a thickness of approximately 5–10 nm are clearly observed. High-resolution TEM (HRTEM) image (Fig. 2d) reveals that these nanosheets exhibit unconsidered crystallinity, with no discernible lattice fringes or diffraction rings in the selected area electron diffraction (SAED) pattern, suggesting an amorphous nature of the surface layer. Moreover, energy-dispersive X-ray spectroscopy (EDS) elemental mapping (Fig. 2e) confirms the successful incorporation of Ni, Fe, and S elements, which are uniformly distributed throughout the nanosheet structure. The homogeneous dispersion of these elements implies effective surface doping, which is expected to modulate the local electronic environment of Ni active sites and synergistically enhance the OER performance.

  Figure 2

  

  Figure 2.  (a) Photograph, (b) SEM image (c) TEM image, (d) HRTEM image of SFN/NM electrode. (e-g) EDS elemental mapping of SFN/NM electrode.

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  The surface composition and chemical states of the SFN/NM electrode were systematically investigated using EDS, XPS, and Raman spectroscopy. EDS analysis (Fig. 3a) confirmed the co-presence of Ni, Fe, S, C, O and Cl with an atomic ratio of ~13.0:4.4:2.5:32.8:43.0:4.0, indicating successful Fe/S co-doping via surface functionalization. Furthermore, a distinct Cl signal was detected, which could be traced back to the residual chloride impurities in the precursor solution during the preparation process. XPS analysis revealed the chemical states of these elements: The Ni 2p spectrum (Fig. 3b) showed peaks at 856.1 eV (Ni 2p_3/2) and 873.6 eV (Ni 2p_1/2), characteristic of Ni²⁺ in hydroxide/oxyhydroxide species [31]. The Fe 2p spectrum (Fig. 3c) displays characteristic features of mixed-valence iron species. Specifically, the Fe 2p_3/2 and Fe 2p_1/2 peaks for Fe³⁺ appear at 712.6 and 725.3 eV, while those for Fe²⁺ are located at 710.3 and 723.9 eV. In addition, two satellite peaks are observed at 714.3 and 727.5 eV, corresponding to the spin-orbit components of Fe 2p_3/2 and 2p_1/2, respectively. These features confirm the coexistence of Fe²⁺ and Fe³⁺ on the surface and indicate the formation of FeOOH-like phases with partial reduction states, likely due to the interaction with the Ni substrate during the functionalization process [32]. The S 2p spectrum (Fig. 3d) displayed dual sulfur environments: A dominant doublet at 163.8/164.9 eV corresponding to S—NiFe bonds in residual S₂O₃²⁻ and a minor peak at 168.5 eV attributed to partially oxidized SO₄²⁻ [33], suggesting incomplete precursor conversion during corrosion. The O 1s spectrum (Fig. 3e) clearly reveals the presence of three distinct chemical states of oxygen, corresponding to metal-oxygen bonds (Ni/Fe—O, 529.6 eV), hydroxyl groups (Ni/Fe—OH, 531.4 eV), and adsorbed water molecules (H₂O, 532.9 eV). Notably, Raman spectroscopy (Fig. 3f) revealed Ni–S stretching vibrations (199.7/321.9 cm⁻¹), seemingly conflicting with XPS-detected S₂O₃²⁻/SO₄²⁻. This apparent discrepancy arises from thiosulfate precursors partially decompose during surface reconstruction, where fractured S-S bonds coordinate with exposed Ni sites to form Ni-S structures. While XPS (surface-sensitive) captured residual S₂O₃²⁻ and oxidized SO₄²⁻ adsorbed on the surface, Raman spectroscopy (probing sub-surface vibrations) preferentially detected the localized Ni-S bonding environment formed through this reconfiguration process. Raman analysis further elucidated structural modifications induced by Fe/S incorporation. The blue-shifted Ni—O vibrations (472.3/553.9 cm⁻¹, compared to pristine Ni(OH)₂, indicated Fe-induced lattice distortion in disordered Ni(OH)₂ clusters [8], while the Fe—O peak at 685.8 cm⁻¹ confirmed amorphous FeOOH formation [34]. These results collectively demonstrate the growth of an amorphous Ni—Fe—S ternary hydroxide layer (NiFeS(OH)_x).

  Figure 3

  

  Figure 3.  (a) SEM-EDS spectrum of SFN/NM. High-resolution XPS spectra of (b) Ni 2p, (c) Fe 2p, (d) S 2p, (e) O 1s for SFN/NM electrode, (f) Raman spectroscopy of SFN/NM electrode.

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  To assess the OER performance of the SFN/NM electrode under practical conditions, its electrochemical behavior was first tested in 6 mol/L KOH, with an NM electrode for comparison. As shown in Fig. 4a, linear sweep voltammetry (LSV) reveals that the SFN/NM electrode exhibits excellent catalytic activity, achieving a current density of 100 mA/cm² at an overpotential of 300 mV. In comparison, NM electrode requires a 160 mV higher overpotential to reach the same current density. Correspondingly, Fig. 4b shows the Tafel slopes of the SFN/NM and NM electrodes, which are 50.62 and 58.28 mV/dec, respectively. Similar Tafel slopes suggest that both electrodes follow a comparable reaction mechanism, with the first electron transfer step (M + OH → M-*OH + e⁻, M is the catalytic active site) dominates the reaction kinetics in the OER process [35,36].

  Figure 4

  

  Figure 4.  Electrocatalytic OER performance of SFN/NM and NM electrodes in 6 mol/L KOH (three-electrode system). (a) LSV polarization curves (without iR). (b) Tafel plots. (c) Electrochemically active surface area (ECSA) values and ECSA-normalized specific activities at 1.60 V (vs. RHE). Comparison of (d) potential at 1.60 V and (e) overpotentials at 10 mA/cm² for SFN/NM and reported electrodes. (f) Nyquist plots from EIS measurements.

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  Electrochemical active surface area (ECSA) plays a pivotal role in electrocatalyst performance, serving as the foundation for active site exposure. To evaluate the ECSA of the electrodes, cyclic voltammetry (CV) was used (Fig. S2 in Supporting information). The NM electrode exhibited an ECSA of 5.66 cm², while the SFN/NM electrode has a significantly larger ECSA of 10.01 cm². Concurrently, enhancing the intrinsic catalytic activity of these sites further contributes to overall efficiency. After normalizing the electrochemical activity based on the ECSA values, Fig. S3 (Supporting information) shows that the intrinsic catalytic activity of the SFN/NM is superior to that of the NM electrode. At 1.60 V (vs. RHE), the SFN/NM achieved a current density of 22.1 mA/cm², which is ~3 times higher than that of the nickel electrode (7.91 mA/cm²) (Fig. 4c). Additionally, Fig. 4d demonstrates that at a potential of 1.6 V, the SFN/NM electrode delivers an excellent current density, surpassing the performance of most nickel-iron-based catalysts and even the iridium-ruthenium-based precious metal catalysts reported in the literature (detailed information are provided in Table S1 in Supporting information) [36-38]. Moreover, Fig. 4e shows that at a current density of 10 mA/cm², the SFN/NM electrode requires an overpotential of only 346 mV, which is lower than that of many previously reported catalysts. This indicates the superior efficiency of the SFN/NM in OER compared to existing materials. The enhanced performance was illustrated as well as its smaller charge transfer resistance (R_ct) and series resistance (R_s), as shown in Fig. 4f, which is consistent with the literature reports [39]. Therefore, the improved activity of the SFN/NM electrode can be attributed to the increased exposure of active sites due to its nanosheet structure, which enhances the overall electrocatalytic performance. Additionally, the electrode has faster reaction kinetics and superior electron transport properties, making it a highly efficient candidate for OER applications [40].

  Following the evaluation of the intrinsic electrocatalytic activity and kinetic characteristics of the SFN/NM electrode, its operational durability under practical electrolysis conditions was systematically investigated to further assess its suitability for industrial-scale applications [41]. As illustrated in Fig. 5a, the SFN/NM underwent a multistep chronopotentiometric test, wherein the current density was progressively increased from 10 mA/cm² to 250 mA/cm² in increments of 50 mA/cm², with each step sustained for 27 h. Throughout the entire 162-h period, the electrode exhibited outstanding stability across all current regimes. The potential response at each stage was steady, and transitions between steps were smooth, without any noticeable voltage spikes or abrupt fluctuations. This behavior suggests that the electrode maintains strong mechanical adhesion and structural integrity under varying electrochemical loads, and that its nanosheet surface facilitates efficient mass and electron transport. To further probe the stability under sustained high current densities, a continuous operation test was conducted at 100 mA/cm² for 90 h (Fig. 5b). The electrode exhibited nearly constant potential over the entire duration, indicating excellent resistance to surface oxidation, dissolution, and delamination under aggressive OER conditions. More notably, ultra-long-term stability was evaluated at a moderate current density of 10 mA/cm² over an extended period exceeding 1600 h (Fig. 5c). Remarkably, the overpotential remained virtually unchanged during the entire test, with total activity decay <0.05%, reflecting exceptional electrochemical robustness. This durability outperforms the majority of state-of-the-art NiFe-based OER catalysts reported [22,42-52], as illustrated in Fig. 5d, emphasizing the superior operational lifespan of the SFN/NM. In addition to long-term performance, the selectivity and efficiency of the OER process were assessed by measuring Faradaic efficiency. As shown in Fig. 5e, the SFN/NM achieved a Faradaic efficiency of ~100%, confirming that nearly all the input electrical energy was converted into oxygen evolution with negligible parasitic side reactions. This high efficiency is indicative of the electrode’s well-maintained catalytic interface under alkaline conditions.

  Figure 5

  

  Figure 5.  Stability and electrochemical performance of SFN/NM electrode for OER in 6 mol/L KOH solution. (a) Multi-step chronoamperometric response performed at sequential current density ranging from 10 mV to 250 mA/cm² with an increment of 50 mA/cm² every 27 h. (b) chronopotentiometric stability cure at 100 mA/cm². (c) Long-term stability at a current density of 10 mA/cm². (d) Comparison of long-term stability for SFN/NM and reported OER catalysts. (e) Faradaic efficiency at a current density of 10 mA/cm².

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  Collectively, these results demonstrate that the SFN/NM electrode not only delivers excellent OER performance in terms of activity and kinetics, but also maintains prolonged electrochemical stability and high selectivity under both moderate and industrially relevant current densities. The combination of facile fabrication, robust durability, and superior performance highlights its strong potential for deployment in scalable water electrolysis systems.

  Following long-term OER testing, TEM image confirmed that the SFN/NM electrode retained its nanosheet morphology without significant aggregation or collapse (Fig. S5 in Supporting information), supporting the excellent mechanical stability. Raman analysis was carried out on the SFN/NM electrode to probe the phase evolution of the catalyst layer. As shown in Fig. S6 (Supporting information), post-OER Raman spectra of the SFN/NM display three characteristic bands centered at ~472, ~553, and ~685 cm⁻¹. The bands at 472 and 553 cm⁻¹ correspond to the E_g and A_1g vibrational modes of γ-NiOOH, indicative of Ni-O bending and stretching vibrations, respectively. Notably, the 472 cm⁻¹ peak exhibits a slight intensity enhancement compared to the pre-catalysis state, suggesting a substantial formation and stabilization of γ-NiOOH during long-term OER. In contrast, the signal at ~685 cm⁻¹, attributed to Fe—O vibrations within disordered FeOOH clusters [53,54], shows a significant decrease in intensity, implying partial dissolution or transformation of Fe-containing amorphous domains under electrochemical conditions. Despite this attenuation, EDS analysis confirms the persistent presence of Fe and S on the electrode surface post-OER (Fig. S7 in Supporting information), indicating that the Fe and sulfur species are not entirely leached but likely redistributed or incorporated into more stable coordination environments. These observations collectively demonstrate that the catalyst surface undergoes dynamic restructuring during electrolysis, leading to the formation of Fe-doped γ-NiOOH as the dominant active phase. This transformation is accompanied by the enrichment of catalytically favorable Ni³⁺ sites and contributes to both the enhanced intrinsic activity and the remarkable long-term operational stability of the SFN/NM electrode.

  To demonstrate the practical scalability and robustness of our room-temperature self-functionalization process, we conducted systematic investigations from laboratory to industrial scale. This synthetic method is characterized by its simplicity, low-cost implementation, and high tolerance to preparation conditions. It does not rely on specific reaction vessels or strictly purified solvents. Notably, even when using tap water to prepare the functionalization solution, the resultant catalysts remain uniform and active, highlighting the robustness and simplicity of the approach. To showcase its scalability, we fabricated a large-format SFN/NM electrode with a size of 1.6 m × 1.6 m using a common fish tank as the reaction container (Fig. 6a). Six spatially distributed regions were selected for characterization. As revealed by SEM (Fig. S6 in Supporting information) and TEM (Fig. S8 in Supporting information), the surface morphology remained consistent across all regions, displaying uniformly distributed nanosheet architectures. Raman spectroscopy (Fig. S9 in Supporting information) further confirmed the reproducibility, with all samples showing characteristic vibrational modes identical to those of the small-area electrodes (Fig. 3f). Electrochemical assessments further affirmed the reproducibility of catalytic performance. As shown in Fig. S10 (Supporting information), all sampling locations exhibited nearly identical LSV curves. As shown in Fig. 6b, the overpotential required to achieve a current density of 10 mA/cm² is 218 ± 3 mV, while 100 mA/cm² is reached at 307 ± 5 mV, indicating that the surface-functionalization method maintains high catalytic performance even upon scale-up. These results strongly support the universality and industrial feasibility of the proposed method.

  Figure 6

  

  Figure 6.  (a) Scale-up experiment of the rapid self-functionalization method, numbers 1 to 6 are randomly selected spatial positions on the electrode, where we conducted systematic characterization to verify the uniformity of our rapid self-functionalization method. (b) OER electrocatalytic assessment of six sampling areas (1.6 m × 1.6 m) from the scaled-up SFN/NM, confirming the reproducibility and consistency of the surface-functionalized electrode in a laboratory three-electrode system. (c) Photograph and (d) schematic diagram of the industrial alkaline electrolyzer provided by PERIC Hydrogen Technologies Co., Ltd. (China). (e) OER polarization curves of electrolyzers employing SFN/NM and Raney nickel electrodes in 30% KOH electrolyte at 80 ℃. (f) Long-term voltage-time profile of SFN/NM-based industrial electrolyzer under a constant current density of ~300 mA/cm².

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  To further evaluate the large-scale catalytic performance under realistic industrial conditions, the SFN/NM electrode (≈ 400 cm²) was integrated into a commercial-scale alkaline water electrolyzer (see details in Table S2 in Supporting information). As depicted in Fig. 6c, the system was constructed by the Equipment of PERIC Hydrogen Technologies Co., Ltd. (China) and operated in 6 mol/L KOH at 80 ℃. The full setup consists of multiple electrolyzer units connected in parallel (Fig. 6d), each consisting of an SFN/NM anode and a commercial Raney nickel cathode (Fig. S11 in Supporting information), separated by an alkaline-stable diaphragm. The electrode pairs are compressed on either side of the separator to ensure efficient ion exchange and electrical contact. For benchmarking, a control group using Raney Ni electrodes for both HER and OER was also tested under identical conditions. Remarkably, the SFN/NM anode demonstrated excellent reproducibility and performance, achieving current densities up to 3000 A/m² at cell voltages below 2.0 V, and sustaining stable operation for over 400 min (Figs. 6e and f, Fig. S12 in Supporting information). These current densities are well within the practical range required for industrial operation (2000–4000 A/m² at 1.8–2.4 V). More importantly, the preparation process of SFN/NM is simple, has zero energy consumption and can be mass-produced. Its cost is significantly lower than that of the currently widely used Reney nickel electrodes. At present, the industrial preparation cost of Raney nickel is approximately 700–1000 CNY/m², while SFN/NM has reduced it by about 50%−70%, demonstrating excellent economy and industrial substitution potential.

  In summary, we report a rapid, energy-free, and scalable surface functionalization strategy to construct a high-performance SFN/NM OER electrode. By immersing commercial Ni mesh in an iron/sulfur solution at room temperature, a uniform amorphous Ni-Fe-S nanosheet layer forms within 3 min, providing abundant active sites and enhanced conductivity. The SFN/NM exhibits low overpotential (300 mV@100 mA/cm²), favorable kinetics (Tafel slope of 50.62 mV/dec), and exceptional durability (>1600 h at 10 mA/cm²), outperforming most Ni-Fe catalysts. And this method is highly reproducible, independent of container geometry, and adaptable to large-area production. Electrodes up to 1.6 m × 1.6 m maintain structural and catalytic uniformity. Integrated into a 400 cm² industrial alkaline electrolyzer, the SFN/NM delivers >300 mA/cm² at <2.0 V and operates stably at 80 ℃. Notably, the production cost of SFN/NM is 50%−70% lower than that of commercial Raney nickel (≈700–1000 CNY/m²), highlighting its economic and practical advantages for industrial water electrolysis.

  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.

  CRediT authorship contribution statement

  Jihong Li: Writing – original draft, Investigation. Zhenying Feng: Investigation. Xiaokun Sheng: Investigation. Keren Chen: Software. Jingming Ran: Investigation. Luyao Li: Investigation. Lei Shi: Writing – review & editing, Data curation. Tongzhou Wang: Writing – review & editing, Investigation. Yida Deng: Supervision.

  Acknowledgments

  This work was supported by the National Natural Science Foundation of China (Nos. 52473299, 52201009, 52301013 and 52231008), the Key Research and Development Program of Hainan Province (No. ZDYF2024GXJS006), International Science & Technology Cooperation Program of Hainan Province (No. GHYF2023007), the Education Department of Hainan Province (No. Hnky2024ZD-2).

  Supplementary materials

  Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2025.111652.

  
  
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  Figure 1  Schematic illustration of the synthesis of SNM/NM electrode via surface functionalization at room temperature aqueous solution with Fe³⁺ and S₂O₃²⁻ ions for only 3 min.

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  Figure 2  (a) Photograph, (b) SEM image (c) TEM image, (d) HRTEM image of SFN/NM electrode. (e-g) EDS elemental mapping of SFN/NM electrode.

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  Figure 3  (a) SEM-EDS spectrum of SFN/NM. High-resolution XPS spectra of (b) Ni 2p, (c) Fe 2p, (d) S 2p, (e) O 1s for SFN/NM electrode, (f) Raman spectroscopy of SFN/NM electrode.

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  Figure 4  Electrocatalytic OER performance of SFN/NM and NM electrodes in 6 mol/L KOH (three-electrode system). (a) LSV polarization curves (without iR). (b) Tafel plots. (c) Electrochemically active surface area (ECSA) values and ECSA-normalized specific activities at 1.60 V (vs. RHE). Comparison of (d) potential at 1.60 V and (e) overpotentials at 10 mA/cm² for SFN/NM and reported electrodes. (f) Nyquist plots from EIS measurements.

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  Figure 5  Stability and electrochemical performance of SFN/NM electrode for OER in 6 mol/L KOH solution. (a) Multi-step chronoamperometric response performed at sequential current density ranging from 10 mV to 250 mA/cm² with an increment of 50 mA/cm² every 27 h. (b) chronopotentiometric stability cure at 100 mA/cm². (c) Long-term stability at a current density of 10 mA/cm². (d) Comparison of long-term stability for SFN/NM and reported OER catalysts. (e) Faradaic efficiency at a current density of 10 mA/cm².

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  Figure 6  (a) Scale-up experiment of the rapid self-functionalization method, numbers 1 to 6 are randomly selected spatial positions on the electrode, where we conducted systematic characterization to verify the uniformity of our rapid self-functionalization method. (b) OER electrocatalytic assessment of six sampling areas (1.6 m × 1.6 m) from the scaled-up SFN/NM, confirming the reproducibility and consistency of the surface-functionalized electrode in a laboratory three-electrode system. (c) Photograph and (d) schematic diagram of the industrial alkaline electrolyzer provided by PERIC Hydrogen Technologies Co., Ltd. (China). (e) OER polarization curves of electrolyzers employing SFN/NM and Raney nickel electrodes in 30% KOH electrolyte at 80 ℃. (f) Long-term voltage-time profile of SFN/NM-based industrial electrolyzer under a constant current density of ~300 mA/cm².

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