Amorphous Metallic NiFeP: A Conductive Bulk Material Achieving High Activity for Oxygen Evolution Reaction in Both Alkaline and Acidic Media

The intrinsic catalytic activity at 10 mA cm^?2 for oxygen evolution reaction (OER) is currently working out at overpotentials higher than 320 mV. A highly efficient electrocatalyst should possess both active sites and high conductivity; however, the loading of powder catalysts on electrodes may often suffer from the large resistance between catalysts and current collectors. This work reports a class of bulk amorphous NiFeP materials with metallic bonds from the viewpoint of electrode design. The materials reported here perfectly combine high macroscopic conductivity with surface active sites, and can be directly used as the electrodes with active sites toward high OER activity in both alkaline and acidic electrolytes. Specifically, a low overpotential of 219 mV is achieved at the geometric current density 10 mA cm^?2 in an alkaline electrolyte, with the Tafel slope of 32 mV dec^?1 and intrinsic overpotential of 280 mV. Meanwhile, an overpotential of 540 mV at 10 mA cm^?2 is attained in an acidic electrolyte and stable for over 30 h, which is the best OER performance in both alkaline and acidic media. This work provides a different angle for the design of high‐performance OER electrocatalysts and facilitates the device applications of electrocatalysts.     

Zirconium‐Regulation‐Induced Bifunctionality in 3D Cobalt–Iron Oxide Nanosheets for Overall Water Splitting

The design of high‐efficiency non‐noble bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is paramount for water splitting technologies and associated renewable energy systems. Spinel‐structured oxides with rich redox properties can serve as alternative low‐cost OER electrocatalysts but with poor HER performance. Here, zirconium regulation in 3D CoFe₂O₄ (CoFeZr oxides) nanosheets on nickel foam, as a novel strategy inducing bifunctionality toward OER and HER for overall water splitting, is reported. It is found that the incorporation of Zr into CoFe₂O₄ can tune the nanosheet morphology and electronic structure around the Co and Fe sites for optimizing adsorption energies, thus effectively enhancing the intrinsic activity of active sites. The as‐synthesized 3D CoFeZr oxide nanosheet exhibits high OER activity with small overpotential, low Tafel slope, and good stability. Moreover, it shows unprecedented HER activity with a small overpotential of 104 mV at 10 mA cm^?2 in alkaline media, which is better than ever reported counterparts. When employing the CoFeZr oxides nanosheets as both anode and cathode catalysts for overall water splitting, a current density of 10 mA cm^?2 is achieved at the cell voltage of 1.63 V in 1.0 m KOH.     

Water‐Plasma‐Enabled Exfoliation of Ultrathin Layered Double Hydroxide Nanosheets with Multivacancies for Water Oxidation

An earth‐abundant and highly efficient electrocatalyst is essential for oxygen evolution reaction (OER) due to its poor kinetics. Layered double hydroxide (LDH)‐based nanomaterials are considered as promising electrocatalysts for OER. However, the stacking structure of LDHs limits the exposure of the active sites. Therefore, the exfoliation is necessary to expose more active sites. In addition, the defect engineering is proved to be an efficient strategy to enhance the performance of OER electrocatalysts. For the first time, this study prepares ultrathin CoFe LDHs nanosheets with multivacancies as OER electrocatalysts by water‐plasma‐enabled exfoliation. The water plasma can destroy the electrostatic interactions between the host metal layers and the interlayer cations, resulting in the fast exfoliation. On the other hand, the etching effect of plasma can simultaneously and effectively produce multivacancies in the as‐exfoliated ultrathin LDHs nanosheets. The increased active sites and the multivacancies significantly contribute to the enhanced electrocatalytic activity for OER. Compared to pristine CoFe LDHs, the as‐exfoliated ultrathin CoFe LDHs nanosheets exhibit excellent catalytic activity for OER with a ultralow overpotential of only 232 mV at 10 mA cm^?2 and possesses outstanding kinetics (the Tafel slope of 36 mV dec^?1). This work provides a novel strategy to exfoliate LDHs and to produce multivacancies simultaneously as highly efficient electrocatalysts for OER.     

Cation‐Modulated HER and OER Activities of Hierarchical VOOH Hollow Architectures for High‐Efficiency and Stable Overall Water Splitting

Atom‐scale modulation of electronic regulation in nonprecious‐based electrocatalysts is promising for efficient catalytic activities. Here, hierarchically hollow VOOH nanostructures are rationally constructed by partial iron substitution and systematically investigated for electrocatalytic water splitting. Benefiting from the hierarchically stable scaffold configuration, highly electrochemically active surface area, the synergistic effect of the active metal atoms, and optimal adsorption energies, the 3% Fe (mole ratio) substituted electrocatalyst (VOOH‐3Fe) exhibits a low overpotential of 90 and 195 mV at 10 mA cm^?2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, respectively, superior than the other samples with a different substituted ratio. To the best of current knowledge, 195 mV overpotential at 10 mA cm^?2 is the best value reported for V or Fe (oxy)hydroxide‐based OER catalysts. Moreover, the electrolytic cell employing the VOOH‐3Fe electrode as both the cathode and anode exhibits a cell voltage of 0.30 V at 10 mA cm^?2 with a remarkable stability over 60 h. This work heralds a new pathway to design efficient bifunctional catalysts toward overall water splitting.     

Designing Highly Efficient and Long‐Term Durable Electrocatalyst for Oxygen Evolution by Coupling B and P into Amorphous Porous NiFe‐Based Material

Oxygen evolution reaction (OER) is of great significance for hydrogen production via water electrolysis, which, however, demands development of highly active, durable, and cost‐effective electrocatalysts in order to stride into a renewable energy era. Herein, highly efficient and long‐term durable OER by coupling B and P into an amorphous porous NiFe‐based electrocatalyst is reported, which possesses an amorphous porous metallic bulk structure and high corrosion resistance, and overcomes the issues associated with currently used catalyst nanomaterials. The PB codoping in the activated NiFePB (a‐NiFePB) delocalizes both Fe and Ni at Fermi energy level and enhances p–d hybridization as simulated by density functional theory calculations. The harmonized electronic structure and unique porous framework of the a‐NiFePB consequently improve the OER activity. The activated NiFePB thus exhibits an extraordinarily low overpotential of 197 mV for harvesting 10 mA cm^?2 OER current density and 233 mV for reaching 100 mA cm^?2 under chronopotentiometry condition, with the Tafel slope harmoniously conforming to 34 mV dec^?1. Impressive long‐term stability of this new catalyst is evidenced by only limited activity decay after 1400 h operation at 100 mA cm^?2. This work strategically directs a way for heading up a promising energy conversion alternative.     

Ruthenium‐Doped Cobalt–Chromium Layered Double Hydroxides for Enhancing Oxygen Evolution through Regulating Charge Transfer

Exploring the origin of transition metal (TM) lattice‐doped layered double hydroxides (LDHs) toward the oxygen evolution reaction (OER) plays a crucial role in engineering efficient electrocatalysts. Without understanding the physics behind the TM‐induced catalytic enhancements, it would be challenging to design the next generation of electrocatalysts. Herein, single Ru atoms are introduced into a CoCr LDHs lattice to improve activity. In 0.1 m KOH, CoCrRu LDHs require only 290 mV overpotential to drive to 10 mA cm^?2 and show a Tafel slope of 56.12 mV dec^?1. Electronic structure analyses based on density functional theory confirm that promoted OER activity originates from synergetic charge transfer among Ru, Cr, and Co elements. Specifically, Ru dopants can downshift d states of Co and enhance electron donation of Cr to oxygenates, which essentially breaks the scaling relation and achieves higher activity. This work provides insights into how single atomic Ru dopant tunes the electronic structures of its neighbor's active site Co and thus increases OER activities.     

Dynamically Stabilized Electronic Regulation and Electrochemical Reconstruction in Co and S Atomic Pair Doped Fe3O4 for Water Oxidation

The electronic regulation and surface reconstruction of earth-abundant electrocatalysts are essential to efficient oxygen evolution reaction (OER). Here, an inverse-spinel Co,S atomic pair codoped Fe₃O₄ grown on iron foam (Co,S-Fe₃O₄/IF) is fabricated as a cost-effective electrocatalyst for OER. This strategy of Co and S atomic pair directional codoping features accelerates surface reconstruction and dynamically stabilizes electronic regulation. Co S atomic pairs doped in the Fe₃O₄ crystal favor controllable surface reconstruction via sulfur leaching, forming oxygen vacancies and Co doping on the surface of reconstructed FeOOH (Co-FeOOH-O_v/IF). Before and after surface reconstruction via in situ electrochemical process, the Fe sites with octahedral field dynamically maintains an appropriate electronic structure for OER intermediates, thus exhibiting consistently excellent OER performance. The electrochemically tuned Fe-based electrodes exhibit a low overpotential of 349 mV at a current density of 1000 mA cm⁻², a slight Tafel slope of 43.3 mV dec⁻¹, and exceptional long-term electrolysis stability of 200 h in an alkaline medium. Density functional theory calculations illustrate the electronic regulation of Fe sites, changes in Gibbs free energies, and the breaking of the restrictive scaling relation between OER intermediates. This work provides a promising directional codoping strategy for developing precatalysts for large-scale water-splitting systems.     

Electronic Structure Evolution in Tricomponent Metal Phosphides with Reduced Activation Energy for Efficient Electrocatalytic Oxygen Evolution

Non‐noble metal catalysts for high‐active electrocatalytic oxygen evolution reaction (OER) are essential in large‐scale application for water splitting. Herein, tricomponent metal phosphides with hollow structures are synthesized from cobalt‐contained metal organic frameworks (MOFs), i.e., ZIF‐67, by tailoring the feeding ratios of Ni and Fe, followed by a high‐temperature reduction and a subsequent phosphidation process. Excellent OER activity and long‐time stability are achieved in 1 m NaOH aqueous solution, with an overpotential of 329 mV at 10 mA cm^?2 and Tafel slope of 48.2 mV dec^?1, even superior to the noble metal‐based catalyst. It is evidenced that the formed (oxyhydr)oxide/phosphate species by in situ electrochemical surface oxidation are responsible for active OER. Accordingly, the simultaneous introduction of external Ni and Fe elements significantly influences the electronic structures of the parent metal phosphides, leading to the in situ electrochemical formation of surface active layer with decreased OER activation energy for greatly improved water oxidation performance. This electronic structure tuning strategy by introducing multicomponent metals demonstrates a versatile method to use MOFs as precursors for synthesizing high‐efficient water splitting electrocatalysts.     

Scalable Fabrication of Highly Active and Durable Membrane Electrodes toward Water Oxidation

The electrocatalytic oxygen evolution reaction (OER) is a highly important reaction that requires a relatively high overpotential and determines the rate of water splitting—a process for producing hydrogen. The overall OER performance is often largely limited by uncontrollable interface when active catalysts are loaded on conductive supports, for which polymer binders are widely used, but inevitably block species transportation channels. Here, a scalable fabrication approach to freestanding graphitized carbon nanofiber networks is reported, which provides abundant sites for in situ growing Fe/Ni catalysts with the improved interface. The fabricated hybrid membrane exhibits high activity and durability toward OER, with an overpotential of 280 mV at a geometrical current density of 10 mA cm^?2 and a Tafel slope of 30 mV dec^?1 in alkaline medium. As implemented as a freestanding electrode, the 3D hybrid structure achieves further enhanced OER performance with an overpotential down to 215 mV at 10 mA cm^?2. This work provides fresh insights into rationally fabricating OER electrocatalysts from the angle of electrode design.     

α‐Ni(OH)2 Originated from Electro‐Oxidation of NiSe2 Supported by Carbon Nanoarray on Carbon Cloth for Efficient Water Oxidation

Development of effective oxygen evolution reaction (OER) electrocatalysts has been intensively studied to improve water splitting efficiency and cost effectiveness in the last ten years. However, it is a big challenge to obtain highly efficient and durable OER electrocatalysts with overpotentials below 200 mV at 10 mA cm^?2 despite the efforts made to date. In this work, the successful synthesis of supersmall α‐Ni(OH)₂ is reported through electro‐oxidation of NiSe₂ loaded onto carbon nanoarrays. The obtained α‐Ni(OH)₂ shows excellent activity and long‐term stability for OER, with an overpotential of only 190 mV at the current density of 10 mA cm^?2, which represents a highly efficient OER electrocatalyst. The excellent activity could be ascribed to the large electrochemical surface area provided by the carbon nanoarray, as well as the supersmall size (≈10 nm) of α‐Ni(OH)₂ which possess a large number of active sites for the reaction. In addition, the phase evolution of α‐Ni(OH)₂ from NiSe₂ during the electro‐oxidation process was monitored with in situ X‐ray absorption fine structure (XAFS) analysis.     

A Microribbon Hybrid Structure of CoOx‐MoC Encapsulated in N‐Doped Carbon Nanowire Derived from MOF as Efficient Oxygen Evolution Electrocatalysts

Developing highly efficient electrocatalysts for oxygen evolution is vital for renewable and sustainable energy production and storage. Herein, nitrogen‐doped carbon encapsulated CoOx‐MoC heterostructures are reported for the first time as high performance oxygen evolution electrocatalysts. The composition can be tuned by the addition of a Mo source to form a nanowire‐assembled hierarchically porous microstructure, which can enlarge the specific surface area, thus exposing more active sites, facilitating mass transport and charge transfer. Moreover, it is demonstrated that the formation of CoOx‐MoC heterostructures and the resulting synergistic effect between MoC and Co facilitate the reaction kinetics, leading to significantly improved oxygen evolution reaction (OER) activity with an onset overpotential of merely 290 mV, and a low overpotential of 330 mV to afford a current density of 10 mA cm^?2. The well‐constructed microarchitecture contributes to superior long term stability electrochemical behaviors. This work provides a facile strategy via composition tuning and structure optimization for the development of next‐generation nonprecious metal‐based OER electrocatalysts.     

Highly Efficient and Stable Water‐Oxidation Electrocatalysis with a Very Low Overpotential using FeNiP Substitutional‐Solid‐Solution Nanoplate Arrays

The development of efficient water‐oxidation electrocatalysts based on inexpensive and earth‐abundant materials is significant to enable water splitting as a future renewable energy source. Herein, the synthesis of novel FeNiP solid‐solution nanoplate (FeNiP‐NP) arrays and their use as an active catalyst for high‐performance water‐oxidation catalysis are reported. The as‐prepared FeNiP‐NP catalyst on a 3D nickel foam substrate exhibits excellent electrochemical performance with a very low overpotential of only 180 mV to reach a current density of 10 mA cm^?2 and an onset overpotential of 120 mV in 1.0 m KOH for the oxygen evolution reaction (OER). The slope of the Tafel plot is as low as 76.0 mV dec^?1. Furthermore, the long‐term electrochemical stability of the FeNiP‐NP electrode is investigated by cyclic voltammetry (CV) at 1.10–1.55 V versus reversible hydrogen electrode (RHE), demonstrating very stable performance with negligible loss in activity after 1000 CV cycles. This present FeNiP‐NP solid solution is thought to represent the best OER catalytic activity among the non‐noble metal catalysts reported so far.     

Electronic Modulation of Nickel Disulfide toward Efficient Water Electrolysis

Developing highly efficient earth‐abundant nickel‐based compounds is an important step to realize hydrogen generation from water. Herein, the electronic modulation of the semiconducting NiS₂ by cation doping for advanced water electrolysis is reported. Both theoretical calculations and temperature‐dependent resistivity measurements indicate the semiconductor‐to‐conductor transition of NiS₂ after Cu incorporation. Further calculations also suggest the advantages of Cu dopant to cathodic water electrolysis by bringing Gibbs free energy of H adsorption at both Ni sites and S sites much closer to zero. It is noteworthy that water dissociation on Cu‐doped NiS₂ (Cu‐NiS₂) surface is even more favorable than those on NiS₂ and Pt(111). Thus, the prepared Cu‐NiS₂ shows noticeably improved performance toward alkaline hydrogen and oxygen evolution reactions (HER and OER). Specifically, it requires merely 232 mV OER overpotential to drive 10 mA cm^?2; in parallel with Tafel slopes of 46 mV dec^?1. Regarding HER, an onset overpotential of only 68 mV is achieved. When integrated as both electrodes for water electrolysis, Cu‐NiS₂ needs only 1.64 V to drive 10 mA cm^?2, surpassing the state‐of‐the‐art Ir/C–Pt/C couple (1.71 V). This work opens up an avenue to engineer low‐cost and earth‐abundant catalysts performing on par with the noble‐metal‐based one for water splitting.     

NiFe Oxalate Nanomesh Array with Homogenous Doping of Fe for Electrocatalytic Water Oxidation

NiFe‐based materials have shown impressive electrocatalytic activity for the oxygen evolution reaction (OER). The mutual effect between proximate Ni and Fe atoms is essential in regulating the electronic structure of the active site to boost the OER kinetics. Detailed studies confirm that the separated monometal phases in NiFe‐based materials are detrimental to OER. Thus, the high‐level blending of Ni and Fe in NiFe‐based OER electrocatalysts is critical. Herein, an NiFe oxalate nanomesh array based on solid solutions between nickel (II) oxalate and iron (II) oxalate is prepared through a facile surfactant‐free approach in the presence of the reductive oxalate anions. The integrated electrode can efficiently catalyze water oxidation to reach a current density of 50 mA cm^?2 with a small overpotential of 203 mV in a 1.0 m KOH aqueous solution. The high efficiency can be attributed to the atomic level mix of Ni and Fe in the solid solutions and the hierarchical porous structure of the nanomesh array. These two aspects bring about fast kinetics, efficient mass diffusion, and quick charge transfer, which are the three major positive factors for a high‐performance heterogenous electrocatalyst.     

Formation of Ni–Fe Mixed Diselenide Nanocages as a Superior Oxygen Evolution Electrocatalyst

Exploring effective electrocatalysts is a crucial requirement for boosting the efficiency of water splitting to obtain clean fuels. Here, a self‐templating strategy is reported to synthesize Ni–Fe mixed diselenide cubic nanocages for the electrocatalytic oxygen evolution reaction (OER). The diselenide nanocages are derived from corresponding Prussian‐blue analog nanocages, which are first obtained by treating the nanocube precursor with a site‐selective ammonia etchant. The resulting Ni–Fe mixed diselenide nanocages perform as a superior OER electrocatalyst, which affords a current density of 10 mA cm^?2 at a small overpotential of 240 mV; a high current density, mass activity, and turnover frequency of 100 mA cm^?2, 1000 A g^?1, and 0.58 s^?1, respectively, at the overpotential of 270 mV; a Tafel slope as small as 24 mV dec^?1; and excellent stability in alkaline medium.     

NiMoFe and NiMoFeP as Complementary Electrocatalysts for Efficient Overall Water Splitting and Their Application in PV‐Electrolysis with STH 12.3%

Complementary water splitting electrocatalysts used simultaneously in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can simplify water splitting systems. Herein, earth‐abundant NiMoFe (NMF) and phosphorized NiMoFeP (NMFP) are synthesized as complementary overall water splitting (OWS) catalysts. First, NMF is tested as both the HER and OER promoter, which exhibits low overpotentials of 68 (HER) and 337 mV (OER). A quaternary NMFP is then prepared by simple phosphorization of NMF, which shows a much lower OER overpotential of 286 mV. The enhanced OER activity is attributed to the unique surface/core structure of NMFP. The surface phosphate acts as a proton transport mediator and expedites the rate‐determining step. With the application of OER potential, the NMFP surface is composed of Ni(OH)₂ and FeOOH, active sites for OER, but the inner core consists of Ni, Mo, and Fe metals, serving as a conductive electron pathway. OWS with NMF‐NMFP requires an applied voltage of 1.452 V to generate 10 mA cm^?2, which is one of the lowest values among OWS results with transition‐metal‐based electrocatalysts. Furthermore, the catalysts are combined with tandem perovskite solar cells for photovoltaic (PV)‐electrolysis, producing a high solar‐to‐hydrogen (STH) conversion efficiency of 12.3%.     

Zinc Substitution‐Induced Subtle Lattice Distortion Mediates the Active Center of Cobalt Diselenide Electrocatalysts for Enhanced Oxygen Evolution

Doping engineering has been an important approach to boost oxygen evolution reaction (OER) activity, while investigation on the dopant‐induced modification of active sites and reaction kinetics remains incomplete. Herein, taking the cubic CoSe₂ as an example, a universal strategy to synergistically achieve active sites and dynamic regulation is developed by incorporating low‐valence Zn. It is revealed that regulation by Zn can facilitate reconstruction of the surface to form active Co oxyhydroxides under OER conditions. By combining theoretical calculations and characterization by various techniques, it is shown that the incorporation of Zn into CoSe₂ can cause subtle lattice distortion and strong electronic interactions, thereby contributing to increased active site exposure and improved OER kinetics. Density functional theory simulations demonstrate that Zn incorporation synergistically optimizes the kinetic energy barrier by promoting co‐adsorption of OER intermediates on a Co site and its adjacent Zn site. As a result, the modified CoSe₂ NAs electrode shows optimized catalytic activity and excellent stability with the low overpotential of only 286 mV required to drive a current density of 10 mA cm^?2 in an alkaline electrolyte.     

Plasmon-promoted oxygen evolution catalysis with Ag nanocrystals loaded α-Co(OH)2 nanosheets

Exploration of low-cost and high efficiency oxygen evolution reaction (OER) electrocatalysts is very important for the large-scale industrial application of alkaline water splitting driven by electricity. The present promising cobalt-based catalysts still leave room to meet the activity requirement. Here, a composite catalyst of α-Co(OH)₂/Ag was synthesized by a simple photochemical deposition route, which was designed to improve the electrocatalytic activity for OER. Moreover, a photoinduced surface plasmon on Ag particles was found to further enhance the catalytic performance under low power of laser irradiation. Loading of silver nanocrystals on α-Co(OH)₂ nanosheets can decrease the overpotential towards OER for 10 mA cm^?2 from 320 to 288 mV, this value can be further decreased of 45 mV under 1000 mW of laser irradiation with a wavelength of 532 nm. The derivation of the catalyst during the OER process was examined, which indicates the structural transformation from α-Co(OH)₂ to CoOOH. The photoinduced surface plasmon modulates the electronic structure of cobalt sites, facilitates the formation of active cobalt species, and induces the enhancement of catalytic activity. These findings may give some hints for plasmon-induced electrocatalysis and the design of advanced electrocatalysts.     

Co9S8 Nanoparticles‐Embedded N/S‐Codoped Carbon Nanofibers Derived from Metal–Organic Framework‐Wrapped CdS Nanowires for Efficient Oxygen Evolution Reaction

Metal–organic frameworks (MOFs) with tunable compositions and morphologies are recognized as efficient self‐sacrificial templates to achieve function‐oriented nanostructured materials. Moreover, it is urgently needed to develop highly efficient noble metal‐free oxygen evolution reaction (OER) electrocatalysts to accelerate the development of overall water splitting green energy conversion systems. Herein, a facile and cost‐efficient strategy to synthesize Co₉S₈ nanoparticles‐embedded N/S‐codoped carbon nanofibers (Co₉S₈/NSCNFs) as highly active OER catalyst is developed. The hybrid precursor of core–shell ZIF‐wrapped CdS nanowires is first prepared and then leads to the formation of uniformly dispersed Co₉S₈/N, S‐codoped carbon nanocomposites through a one‐step calcination reaction. The optimal Co₉S₈/NSCNFs‐850 is demonstrated to possess excellent electrocatalytic performance for OER in 1.0 m KOH solution, affording a low overpotential of 302 mV to reach the current density of 10 mA cm^?2, a small Tafel slope of 54 mV dec^?1, and superior long‐term stability for 1000 cyclic voltammetry cycles. The favorable results raise a concept of exploring more MOF‐based nanohybrids as precursors to induce the synthesis of novel porous nanomaterials as non‐noble‐metal electrocatalysts for sustainable energy conversion.     

Turning Waste into Treasure: Regulating the Oxygen Corrosion on Fe Foam for Efficient Electrocatalysis

Iron corrosion causes a great damage to the economy due to the function attenuation of iron‐based devices. However, the corrosion products can be used as active materials for some electrocatalytic reactions, such as oxygen evolution reaction (OER). Herein, the oxygen corrosion on Fe foams (FF) to synthesize effective self‐supporting electrocatalysts for OER, leading to “turning waste into treasure,” is regulated. A dual chloride aqueous system of “NaCl‐NiCl₂” is employed to tailor the structures and OER properties of corrosion layers. The corrosion behaviors identify that Cl^? anions serve as accelerators for oxygen corrosion, while Ni²⁺ cations guarantee the uniform growth of corrosion layers owing to the appeared chemical plating. The synergistic effect of “NaCl‐NiCl₂” generates one of the highest OER activities that only an overpotential of 212 mV is required to achieve 100 mA cm^?2 in 1.0 m KOH solution. The as‐prepared catalyst also exhibits excellent durability over 168 h (one week) at 100 mA cm^?2 and promising application for overall water splitting. Specially, a large self‐supporting electrode (9 × 10 cm²) is successfully synthesized via this cost‐effective and easily scale‐up approach. By combining with corrosion science, this work provides a significant stepping stone in exploring high‐performance OER electrocatalysts.