Electrocatalytic Oxygen Evolution Reaction Research Articles

Manipulating electron redistribution induced by asymmetric coordination for electrocatalytic water oxidation at a high current density

Electronic structure manipulation with regard to active site coordination is an effective strategy to improve the electrocatalytic oxygen evolution reaction (OER) activity. Herein, we present the structure–activity relationship between oxygen-atom-mediated electron rearrangement and active site coordination asymmetry. Ni2+ ions are introduced to FeWO4 on Ni foam (NF) via self-substitution to break the symmetry of the FeO6 octahedron and regulate d-electron structure of Fe sites. Structural regulation optimizes the adsorption energy of hydroxyl on the Fe sites and promotes the partial formation of hydroxyl oxide with high OER activity on the tungstate surface. Fe0.53Ni0.47WO4/NF with the asymmetric FeO6 octahedron of Fe sites can achieve an ultralow overpotential of 170 mV at 10 mA cm−2 and 240 mV at 1000 mA cm−2 with robust stability for 500 h at high current density under alkaline conditions. This research develops novel electrocatalysts with impressive OER performance and provides new insights into the design of highly active catalytic systems.

Defect Engineering in Bimetallic NiFe‐BTC for Boosting Electrocatalytic Oxygen Evolution Reaction through Coordinated Ionic Liquids

AbstractCoordinatively unsaturated metal (CUM) sites in metal organic frameworks (MOFs) have demonstrated distinct catalytic activities, yet remain great challenges in their designing and engineering. Herein, a novel “Coordination Geometric Hindrance” approach based on ionic liquids (ILs) is proposed for defects construction in bimetallic MOF, of which the steric effect of competitively coordinated anions of imidazole ILs ([EMIM]X) enables the interference with the ordered growth of bimetallic NiFe‐MOFs. Specifically, the PF6− anion displays the strongest binding energy with metals Ni and Fe, accordingly, facilitates the formation of CUM sites in NiFe‐BTC/IL‐PF6. Taking both advantages of CUM defects and good intrinsic conductivity of IL, NiFe‐BTC/IL‐PF6 achieves a superior electrocatalytic performance in the oxygen evolution reaction (OER), with the overpotential as low as 210 mV at 10 mA cm−2, and the Tafel slope of 103 mV dec−1, thus, giving an 18‐fold larger TOF of the commercial OER catalyst of RuO2.

Insight into the surface-reconstruction of metal–organic framework-based nanomaterials for the electrocatalytic oxygen evolution reaction

Insight into the surface-reconstruction of metal–organic framework-based nanomaterials for the electrocatalytic oxygen evolution reaction

Tuned d-band states over lanthanum doped nickel oxide for efficient oxygen evolution reaction

The d-band state of materials is an important descriptor for activity of oxygen evolution reaction (OER). For NiO materials, there is rarely concern about tuning their d-band states to tailor the OER behaviors. Herein, NiO nanocrystals with doping small amount of La3+ were used to regulate d-band states for promoting OER activity. Density of states calculations based on density functional theory revealed that La3+ doping produced upper shift of d-band center, which would induce stronger electronic interaction between surface Ni atoms and species of oxygen evolution reaction intermediates. Further density functional theory calculation illustrated that La3+ doped NiO possessed reduced Gibbs free energy in adsorbing species of OER intermediate. Predicted by theoretical calculations, trace La3+ was introduced into crystal lattice of NiO nanoparticles. The La3+ doped NiO nanocrystal showed much promoted OER activity than corresponding pristine NiO product. Further electrochemical analysis revealed that La3+ doping into NiO increased the intrinsic activity such as improved active sites and reduced charge transfer resistance. The in-situ Raman spectra suggested that NiO phase in La3+ doped NiO could be better maintained than pristine NiO during the OER. This work provides an effective strategy to tune the d-band center of NiO for efficient electrocatalytic OER.

Doping of high‐valence metals and their electrocatalytic oxygen evolution reaction in metal/porous carbon composites

AbstractPreparing high‐efficiency, durable and low overpotential electrocatalytic materials for oxygen evolution reaction (OER) plays a key role in water electrolysis. At present, electrochemical water separation technology has become the most promising sustainable hydrogen production process. The inherent hysteresis kinetics of oxygen evolution reaction (OER) is the key bottleneck of water electrolysis, which greatly restricts the energy conversion efficiency and practical large‐scale application. Herein, a facile method is developed to synthesize a series of trimetallic (Mo/Ni/Fe) metal‐organic frameworks (MOFs)‐derived carbon nanoparticles (CNPs) with various Fe content, and a Fe‐dependent volcano‐type plot can be drawn out for MoNiFex‐CNPs. The optimized MoNiFe0.4‐CNPs demonstrate superior electrocatalytic performance with a low overpotential of only 227 mV@10 mA cm−2 and excellent durability of 100 h. Its excellent OER performance is attributed to the synergistic effect of Fe/Ni bimetallic regulated by Mo. This work improved the catalytic performance of MOFs in the OER and proposed a new strategy for the structural design of MOFs.

Integrated core-shell assembly of Ni3S2 nanowires and CoMoP nanosheets as highly efficient bifunctional electrocatalysts for overall water splitting

A paradigm for the rational design of active, abundant, and inexpensive bifunctional electrocatalysts with acceptable electrochemical energy conversion rates has yet to be achieved. Here, we describe the assembly of a superior bifunctional electrocatalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities based on a CoMoP/Ni3S2 multicomponent, heterointerface consisting of a freestanding electrocatalyst prepared by hydrothermal-phosphidation, consisting of one-dimensional Ni3S2 covered with Cereus cactus–like hierarchical CoMoP nanosheets. The resulting three dimensional CoMoP/Ni3S2 core-shell heterostructure exhibited remarkable HER and OER electrocatalysis, benefiting from modulated electronic structures, rapid mass diffusion, reduced charge-transfer resistance, and a larger electrochemically active surface area. Due to these superior functionalities, the CoMoP/Ni3S2 requires only 96.8 mV (at η10) for HER catalysis and 270 mV (at η50) for an OER process. Furthermore, a stable water-splitting device using CoMoP/Ni3S2 for both the anode and cathode required a low cell voltage of 1.54 V at 10 mA cm−2. This work represents a significant advance in interface construction of transition-metal phosphide/sulfide for long-term water splitting.

Fe-Incorporated Nickel-Based Bimetallic Metal-Organic Frameworks for Enhanced Electrochemical Oxygen Evolution.

Developing cost-effective and high-efficiency catalysts for electrocatalytic oxygen evolution reaction (OER) is crucial for energy conversions. Herein, a series of bimetallic NiFe metal-organic frameworks (NiFe-BDC) were prepared by a simple solvothermal method for alkaline OER. The synergistic effect between Ni and Fe as well as the large specific surface area lead to a high exposure of Ni active sites during the OER. The optimized NiFe-BDC-0.5 exhibits superior OER performances with a small overpotential of 256 mV at a current density of 10 mA cm-2 and a low Tafel slope of 45.4 mV dec-1, which outperforms commercial RuO2 and most of the reported MOF-based catalysts reported in the literature. This work provides a new insight into the design of bimetallic MOFs in the applications of electrolysis.

Mechanochemical Post‐Synthesis of Metal–Organic Framework‐Based Pre‐Electrocatalysts with Surface FeONi/Co Bonding for Highly Efficient Oxygen Evolution

AbstractRational surface engineering of metal–organic frameworks (MOFs) provide potential opportunities to address the sluggish kinetics of oxygen evolution reaction (OER). However, the development of MOF‐based materials with low overpotentials remains a great challenge. Herein, a post‐synthesis strategy to prepare highly efficient MOF‐based pre‐electrocatalysts via all‐solid‐phase mechanochemistry is demonstrated. The surface of a Fe‐based MOF (MIL‐53) can be reconstructed and anchored with atomically dispersed Ni/Co sites. As expected, the optimized M‐NiA‐CoN exhibits a very low overpotential of 180 mV at 10 mA cm−2 and a small Tafel slope of 41 mV dec−1 in 1 m KOH electrolyte. The superior electrocatalytic OER activity is mainly due to the formation of surface FeONi/Co bonding. Furthermore, density functional theory calculations reveal that the transformation from *OH to *O is the rate‐determining step and the electrocatalytic OER activity trend at different metal sites is Co > Ni≈Fe.

Inert Mg Incorporation to Break the Activity/Stability Relationship in High-Entropy Layered Hydroxides for the Electrocatalytic Oxygen Evolution Reaction

Ni-based layered double hydroxides (LDHs) have been demonstrated as the most active catalyst for the oxygen evolution reaction in alkaline media but suffer from poor stability. Herein, we report the rational breaking of the activity/stability trade-off by a strategy of inert Mg-involved high-entropy coordination. The as-developed high-entropy FeCoNiMg-LDH nanosheets exhibit not only high catalytic activity (302 mV at 100 mA cm–2) but also an unprecedented stability with almost no performance decline at a large current density of 300 mA cm–2. The combined structural investigations and theoretical calculations reveal that the synergistic electronic coupling provides active Ni in desired electronic states, leading to an optimized adsorption energy of intermediates, while the construction of high configuration entropy as well as the formation of the Mg–O interfacial bond can effectively mitigate phase segregation and transformation and thus improve the stability. The current insights into unveiling the composition–activity–stability of high-entropy coordination may provide valuable guidance for the design of catalysts for various electrochemical reactions.

Interface coupling induced built-in electric fields boost electrocatalytic oxygen evolution reaction over MOF@LDHs core-shell nanocones

Constructing built-in electric fields can guide the efficient electron transfer, which will benefit for the modification of electronic structure to substantially promote the intrinsically catalytic activity toward oxygen evolution reaction (OER). Here, a p-p heterojunction composed of metal-organic frameworks (MOFs) and layered double hydroxides (LDHs) with rich heterointerfaces is reported. As a proof of concept, the as-prepared MOF@LDH nanocones are demonstrated to be highly effective for OER electrocatalysis, delivering a current density of 10 mA·cm−2 with the overpotential of merely 270 mV, along with excellent electrochemical cycle stability. The built-in electric field in such p-p heterojunction can boost electron transfer in OER. More importantly, the presence of rich heterointerfaces also endow oxygen intermediates with a balanced adsorption/desorption capability, thus achieving superb electrocatalytic performance. This work realizes the effective integration of built-in electric fields and heterointerface effect for synergistically promoting catalytic OER performance.

Promoting the activation of H2O via vacancy defects over metal-organic framework-derived cobalt oxide for enhanced oxygen evolution

Engineering the electronic structures of transition metal oxides via vacancy defects is an efficient approach to enhance their catalytic performances, while facilely creating vacancy defects and deeply exploring the effects still remain challenging. Herein, a facile reduction method was applied to introduce oxygen vacancy defects into metal-organic frameworks (MOFs)-derived cobalt oxide (Co3O4) polyhedron. Using zeolitic imidazolate framework-67 (ZIF-67) as Co source and self-sacrificial template, Co3O4 with polyhedron morphology and porous structure was synthesized, and then oxygen vacancy defects were introduced into the as-prepared Co3O4 through one-step NaBH4 reduction treatment. Strikingly, the obtained electrocatalyst (denoted as Co3O4-x) exhibited a larger current density (112.9 mA cm−2 vs. 1.75 V), a lower overpotential (335 mV at 10 mA cm−2) and a smaller Tafel slope (83 mV dec−1) than the Co3O4, which is even superior to the state-of-the-art IrO2 catalyst. Moreover, experiment results combined with density-functional theory (DFT) calculations revealed that the existence of oxygen vacancies could improve the conductivity, promote the activation of H2O and reduce the potential of potential-limited step (PLS), thus greatly boosting electrocatalytic oxygen evolution reaction (OER) performances. This work reported a strategy for preparing defect-rich OER electrocatalysts, and also provided a deep understanding of the defect effects on catalytic performances.

Double etch strategy induced morphologic transformation engineering of Fe–Ni hydroxide for the efficient and stable oxygen evolution

Developing high-efficiency and steady nickel-iron based catalysts are of great significance for oxygen evolution reaction (OER). However, the rarity of active sites exposed to electrolytes is difficult, limiting their OER properties. Herein, an innovative double-etch strategy has been developed to synthesize Fe–NiOH@NF nanosheet supported on nickel foam. Where NH4+ was applied to change the morphology of precursor (NiNH4PO4) from one-dimensional (1D) to two-dimensional (2D) to expose a larger solution contact area and the etch of OH− thinned the layered structure in the process of transforming Fe–NiNH4PO4 for Fe-β-Ni(OH)2. And the double etching strategy makes Fe–NiOH@NF-5 possess excellent electrocatalytic OER performance, when reaching the current densities of 100 and 1000 mA cm−2, the obtained catalytic materials only required a low overpotential of 260 and 320 mV, respectively. Meanwhile, the stability of the structure was also verified in strong corrosion environment (1 M KOH), and the catalytic activity presents unattenuated after stable operation at 100 mA cm−2 for 80 h. Density functional theory (DFT) confirmed that the optimized adsorption intermediates and conductivity were the keys to the better performance. The morphology control strategy of this work provided a significant reference for the improved OER properties of transition metal-based catalysts.

The role of aluminium in metal–organic frameworks derived carbon doped with cobalt in electrocatalytic oxygen evolution reaction

Water electrolysis is one of the most crucial processes in the development of new energy sources, where ultra-clean fuel is produced - hydrogen. Oxygen evolution reaction (OER) is the sluggish process of overall water splitting. Therefore, this study presents the design, characterization and electrochemical study of cobalt-based electrocatalysts embedded into porous carbons derived from an Al-metal–organic framework (MOF). The key aspects to be revealed were carbonization temperature and aluminium impact on the composite electrochemical performance. It was found that aluminium presence boosts the OER performance of the anode via lowering electrolyte resistance, reaching an overpotential of 380 mV at the current density of 10 mA/cm−2, which is improved by 80 mV compared to the composite without aluminium. Similar effect was present in EIS measurement, where the electrocatalyst functionalized with cobalt in the presence of aluminium showed the lowest resistances, 0.89 Ω and 2.82 Ω for R1 and R2. This is due to the formation of additional electrocatalytically active species in the form of Al-Co alloy what was clearly proved by the XPS study. It shows that cobalt favoured aluminium to act simultaneously as active sites accelerating the efficiency of the OER process. Additionally, carbon played the role of a booster of the OER activity of cobalt with sustained high durability during cycling. Therefore, a facile procedure to tune the structure of carbon-based structures derived from Al-based metal–organic frameworks is proposed and the resulting cobalt/aluminium modification serves as a robust electrocatalyst for OER.

Dimensionality effects of g-C3N4 from wettability to solar light assisted self-cleaning and electrocatalytic oxygen evolution reaction

Unique interfacial properties of 2D materials make them more functional than their bulk counterparts in a catalytic application. In the present study, bulk and 2D graphitic carbon nitride nanosheet (bulk g-C3N4 and 2D-g-C3N4 NS) coated cotton fabrics and nickel foam electrode interfaces have been applied for solar light-driven self-cleaning of methyl orange (MO) dye and electrocatalytic oxygen evolution reaction (OER), respectively. Compared to bulk, 2D-g-C3N4 coated interfaces show higher surface roughness (1.094 > 0.803) and enhanced hydrophilicity (θ ∼ 32° < 62° for cotton fabric and θ ∼ 25° < 54° for Ni foam substrate) due to oxygen defect induction as confirmed from morphological (HR-TEM and AFM) and interfacial (XPS) characterizations. The self-remediation efficiencies for blank and bulk/2D-g-C3N4 coated cotton fabrics are estimated through colorimetric absorbance and average intensity changes. The self-cleaning efficiency for 2D-g-C3N4 NS coated cotton fabric is 87%, whereas the blank and bulk-coated fabric show 31% and 52% efficiency. Liquid Chromatography-Mass Spectrometry (LC-MS) analysis determines the reaction intermediates for MO cleaning. 2D-g-C3N4 shows lower overpotential (108 mV) and onset potential (1.30 V) vs. RHE for 10 mA cm−2 OER current density in 0.1 M KOH. Also, the decreased charge transfer resistance (RCT = 12 Ω) and lower Tafel's slope (24 mV dec−1) of 2D-g-C3N4 make it the most efficient OER catalyst over bulk-g-C3N4 and state-of-the-art material RuO2. The pseudocapacitance behavior of OER governs the kinetics of electrode-electrolyte interaction through the electrical double layer (EDL) mechanism. The 2D electrocatalyst demonstrates long-term stability (retention ∼94%) and efficacy compared to commercial electrocatalysts.

Construction of NiFe(CN)5NO/Ni3S2 hierarchical submicro-rods on nickel foam as advanced oxygen evolution electrocatalysts

The development of cheap, abundant, and highly efficient electrocatalysts for the oxygen evolution reaction (OER) is urgently needed for hydrogen production from water splitting. Herein, we demonstrate a novel OER electrocatalyst (NiFe(CN)5NO/Ni3S2) prepared by coupling Ni3S2 and a bimetallic metal–organic framework (MOF) of NiFe(CN)5NO on nickel foam (NF) via a simple two-step route. The NiFe(CN)5NO/Ni3S2 electrocatalyst displays an interesting rod-like hierarchical architecture assembled by ultrathin nanosheets. The combination of NiFe(CN)5NO and Ni3S2 optimizes the electronic structure of the metal active sites and increases the electron transfer capability. Benefitting from the synergistic effect between Ni3S2 and the NiFe-MOF as well as the unique hierarchical architecture, the NiFe(CN)5NO/Ni3S2/NF electrode exhibits excellent electrocatalytic OER activity with ultralow overpotentials of 162/197 mV at 10/100 mA cm−2 and an ultrasmall Tafel slope of 26 mV dec-1 in 1.0 M KOH, which are far superior to those of the individual NiFe(CN)5NO, Ni3S2 and commercial IrO2 catalysts. In particular, unlike common metal sulfide-based electrocatalysts, the composition, morphology and microstructure of the NiFe-MOF/Ni3S2 composite electrocatalyst can be well retained after the OER, which endows it with fantastic long-term durability. This work offers a new strategy for the construction of novel and high-efficiency MOF-based composite electrocatalysts for energy applications.

Silver nanoparticles embedded in phosphorus and nitrogen-doped hierarchical hollow porous carbon for efficient supercapacitor and electrocatalytic water oxidation

Supercapacitor (SC) and oxygen evolution reaction (OER) require highly efficient multifunctional catalysts prepared from non-noble metals and heteroatoms. In this work, we have developed silver (Ag) decorated on phosphorus (P), nitrogen (N) -doped hollow porous carbon (HPC) prepared through hydrothermal followed by pyrolysis method. The prepared bifunctional electrocatalyst was studied through different characterization techniques. As-prepared HPC-UD, P-HPC-UD, and Ag@P-HPC-UD integrate high-level P-doping, large specific surface areas (up to 1452, 1247, and 528 m2 g−1), and hierarchical multipores of cross-linked micro and mesopore channels. As a result, the Ag and P modified the active sites and electronic structure of the HPC bifunctional catalyst, which is beneficial for the electrocatalytic process. As a result, the Ag@P-HPC-UD catalyst provides an outstanding specific capacitance value of 388 F g−1 at 0.5 A g−1 when used as a SC electrode. Furthermore, the Ag@P-HPC-UD electrocatalyst exhibited efficient OER behavior with a lower overpotential of 165 mV at 10 mA cm−2 current density and a lower Tafel value of 55.46 mV dec−1, which is remarkably superior to commercial RuO2 electrocatalyst. Therefore, the Ag@P-HPC-UD electrocatalyst pathway for a new revolution in developing a highly impressive carbon-based electrode towards both SC and electrocatalytic OER performance.

Solution Plasma‐Assisted Multivariate Metal Nanoalloys Encapsulated with Carbon Dots for Efficient Oxygen Evolution Reaction

AbstractTo accelerate the reaction kinetics of electrocatalytic oxygen evolution reaction (OER), a multicomponent CDs@(PdFeNiCo)Nbx nanohybrid comprising multiple metal nanoalloys and carbon quantum dots (CDs) was in situ generated by treating the mixture of Nb2C quantum dots (Nb2C QDs) and a variety of metal ions (M2+=Pd2+, Fe2+, Co2+, Ni2+) through the solution plasma (SP) modification technique. The CDs@(PdFeNiCo)Nbx catalyst was further explored as an electrocatalyst for OER in alkaline solution. Under nitrogen plasma irradiation with high input power (200 W), diverse bimetallic nanoalloy particles, including NbPd3, FeNb, NbNi3, and CoNbO4 nanoalloys, were generated, accompanied with the decomposition of Nb2C QDs into CDs. In view of the synergic effect between multivariate metal active sites and highly conjugated CD network, the developed CDs@(PdFeNiCo)Nbx electrocatalyst showed a small overpotential of 240 mV for achieving the current density of 10 mA cm−2, together with a very low Tafel slope of 62 mV dec−1, which substantially outperformed those of the state‐of‐the‐art metal electrocatalysts and was competitive with most metal oxides. The CDs@(PdFeNiCo)Nbx electrocatalyst also showed a negligible overpotential change during 30 h chronopotentiometry measurement. The present work can provide a feasible alternative strategy for the development of an excellent OER electrocatalyst using the SP modification method.

Modulation of iron-based perovskites for enhanced electrocatalytic oxygen evolution reaction by a multi-method approach

Perovskite oxides have been a hot topic of research in the field of water electrolysis due to their tunable construction; however, the poor conductivity and insufficient electrocatalytic activity of extensively studied iron-based perovskites have hindered their widespread availability. While most reported schemes focus on a stand-alone measure to modulate the physicochemical properties of perovskite oxides, herein, we utilize a multi-method approach to improving the parent perovskite SrFeO3-δ (SF). A novel perovskite oxide with a nominal composition of Sr0.9Fe0.6Co0.2Ni0.2O3-δ (S9FCN) is formulated for efficiently catalyzing oxygen evolution reaction (OER) in alkaline electrolytic water, employing the B-site co-doping with the dynamic cations Co, Ni and the A-site Sr deficiency from a highly tunable construction management to enhance the electrocatalytic activity of the targeted perovskite sample. Utilizing this concept, encouragingly, the constructed S9FCN perovskite catalyst exhibits excellent OER catalytic activity with low overpotential of 340 mV at 10 mA cm-2, high mass activity (153.32 A gcatalyst-1) and specific activity (1.91 mA cmBET-2 and 0.11 mA cmECSA-2) under a 400 mV overpotential, along with outstanding electrochemical durability without obvious degradation up to 40 h, which is much superior to that of its parent SF and stoichiometric SFCN counterparts. The improvement of electrochemical performance of iron-based perovskite catalysts by a multi-method approach stands a chance of speeding up the practical application of OER electrocatalysts.

Electrocatalytic behavior of Ni-Co-Fe3O4 nanospheres for efficient oxygen evolution reaction

Herein, a simple hydrothermal approach has been used to synthesize nickel and cobalt co-doped ferric oxide (Ni-Co-Fe3O4) nanospheres and tested for electrocatalytic oxygen evolution reaction (OER). The different characterization outcomes verify the successful co-doping of Ni and Co into Fe3O4. The as-synthesized Ni-Co-Fe3O4 nanospheres demonstrated better electrochemical properties as compared to its counterparts Fe3O4, Co-Fe3O4, and Ni-Fe3O4. At a define current density of 10 mA cm−2, the Ni-Co-Fe3O4 electrocatalyst obtained a smaller overpotential of 243 mV and the tafel value of about 54.84 mV dec-1. In addition, Ni-Co-Fe3O4 acquired efficient electrochemical stability for 25 h duration reaching current density of 10 mA cm−2 in 1 M potassium hydroxide solution. Furthermore, it is determined that the outstanding electrocatalytic OER activity of the prepared material as a result of its distinct morphology. Analyses using the density functional theory revealed that less hydroxyl ions adhesion energy is very beneficial for the OER of crystalline Ni-Co-Fe3O4 nanospheres. The least adhesive energy for adsorption of hydroxyl ion at the top of the Fe atom in Ni-Co-Fe3O4 further confirmed their outstanding results in improving electrocatalytic OER performance. Our work gives a decent option for future transition metal oxides based electrode nanomaterials for water electrolysis applications.

Rapid fabrication of NiFe(OH)x/Fe0.2Co-Se complexes for oxygen evolution reaction electrocatalysis

Exploiting the inexpensive and efficient oxygen evolution reaction (OER) electrocatalysts is crucial for improving the efficiency of electrocatalytic water splitting (EWS), since the slow 4-electron OER process is a rate-limiting step in EWS. Herein, we prepared the NiFe(OH)x/Fe0.2Co-Se complexes on carbon paper (CP) via an easy two-step electrochemical deposition strategy. By varying the doping amount of Fe and the deposition time of Fe0.2Co-Se, the OER property of NiFe(OH)x/Fe0.2Co-Se/CP was optimized to the best: only requiring low overpotentials of 243 and 277 mV at the current density of 20 and 100 mA/cm2 (j20 and j100) and a small Tafel slope of 36.8 mV/dec, along with a terrific long-term durability in 1 M KOH. According to the experimental results, the rich exposed active sites, improved intrinsic site activity and enhanced electrical conductivity lead to the superior OER performance. Our work will provide some inspiration for designing other metal selenide/hydroxide heterostructures for other energy conversion or storage applications.