Water Splitting In Alkaline Media Research Articles

Preparation of Ni-Fe alloy foam for oxygen evolution reaction

NiFe oxyhydroxide and hydroxide have been proven to be efficient and earth-abundant non-noble metal catalysts for the oxygen evolution reaction (OER). However, the fragile nature of these oxyhydroxides or hydroxides severely reduces the long-term stability and hinders the industrial applications. Meanwhile, the poor electrical conductivity of these materials also has seriously led to the higher overpotential when applying to the OER. Herein, a novel method using polyurethane (PU) sponge as electroplating was carried out to design NiFe alloy foam with different Fe content for OER. The physical properties of NiFe alloy foams were characterized by Scanning Electronic Microscopy (SEM), Energy Dispersive System (EDS) and X-Ray Diffraction (XRD), respectively, suggesting that the porous NiFe alloy is formed with uniform distribution of Ni and Fe. The OER performance was tested by Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), Electrochemical Impedance Spectroscopy (EIS), I-t, etc. The results showed that the doped Fe could significantly improve the conductivity and OER performance of Ni foam. The NiFe alloy foam with 30% Fe exhibited 292 mV overpotential at 10 mA/cm2 and the Tafel slope 126.12 mV/decade in alkaline solution with excellent long-term stability. Without any complex electrode preparation processes and binders, NiFe alloy foam is much convenient to use as anode of water splitting in alkaline media for industrial applications.

Palladium nanoparticles embedded in microporous carbon as electrocatalysts for water splitting in alkaline media

The creation of carbon matrices with a high surface area for effective catalytic activity is an urgent task today, especially in the field of electrocatalysis. In this study, microporous carbon (MPS) with a surface area of about 1300 m2 g−1 was produced from raw plant waste (apricot pit shells) by successive thermal carbonation and chemical treatment. The MPS was impregnated with H2PdCl6 and calcined at various temperatures under a H2–Ar flux. The obtained Pd-NP@MPC (nanoparticle size from 1 to 25 nm) catalysts were characterized in detail by XRD, SEM, TEM and BET methods. Electrochemical tests show that the prepared composites exhibit high electrocatalytic activity and remarkable stability over time (over 50 h) for the HER process and overall water splitting performance. The electrodes have very low overpotentials (η) of 95–117 mV for HER in 1 M KOH at a current density of 100 mA cm−2. Furthermore, the Pd-NP@MPC-300 electrode can reach a high current density of 300 mA cm−2 at η merely of 170 mV and shows excellent electrocatalytic stability in prolonged water electrolysis. The relationships between MPC matrix characteristics, Pd NPs size and electrocatalytic properties are discussed in this paper.

Copper-Incorporated heterostructures of amorphous NiSex/Crystalline NiSe2 as an efficient electrocatalyst for overall water splitting

• Novel Cu-implanted heterostructure of amorphous NiSe x /crystalline NiSe 2 is prepared. • Catalyst needs overpotential of 156.9 mV for HER and 339 mV for OER at 10 mA cm −2. • The catalyst-based electrolyzer requires a low cell voltage of 1.62 V at 10 mA cm −2. • The catalyst-based electrolyzer shows a long-term stability of 21.5 h in 1.0 M KOH. In this research, we designed a novel heterostructure of porous amorphous-crystalline nickel selenide incorporated with copper (Cu-(a-NiSe x /c-NiSe 2 )) and shelled over one-dimensional TiO 2 nanorods (NRs) to simultaneously accelerate both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics in alkaline environment. The Cu-(a-NiSe x /c-NiSe 2 )/TiO 2 NRs supported by carbon cloth displayed as an effective bifunctional catalyst, which required low overpotentials of 156.9 mV for HER and 339 mV for OER to achieve a current response of 10 mA cm −2 in 1.0 M KOH medium. An electrolyzer derived from the Cu-(a-NiSe x /c-NiSe 2 )/TiO 2 NRs material allowed an operation voltage of 1.62 V at 10 mA cm −2 along with good long-term stability after 21.5 h operation towards water splitting in alkaline medium. This achievement was resulted from the fine-tuned 3D porous architecture of the amorphous NiSe x -crystalline NiSe 2 heterostructures doped by copper, which led to significant modulation of electronic properties as well as large surface of exposed electroactive site/types, thereby effectively promoting the catalytic performance. This study suggested a rational approach of structure and shape engineering to design a potential catalyst for producing green hydrogen via water spitting.

Double Perovskite Cobaltites Integrated in a Monolithic and Noble Metal-Free Photoelectrochemical Device for Efficient Water Splitting.

Water photoelectrolysis has the potential to produce renewable hydrogen fuel, therefore addressing the intermittent nature of sunlight. Herein, a monolithic, photovoltaic (PV)-assisted water electrolysis device of minimal engineering and of low (in the μg range) noble-metal-free catalysts loading is presented for unassisted water splitting in alkaline media. An efficient double perovskite cobaltite catalyst, originally developed for high-temperature proton-conducting ceramic electrolyzers, possesses high activity for the oxygen evolution reaction in alkaline media at room temperatures too. Ba1–xGd1–yLax+yCo2O6−δ (BGLC) is combined with a NiMo cathode, and a solar-to-hydrogen efficiency of 6.6% in 1.0 M NaOH, under 1 sun simulated illumination for 71 h, is demonstrated. This work highlights how readily available earth-abundant materials and established PV methods can achieve high performance and stable and monolithic photoelectrolysis devices with potential for full-scale applications.

An efficient way to improve water splitting electrocatalysis by electrodepositing cobalt phosphide nanosheets onto copper nanowires

Herein, catalysts with improved electrocatalysis of water splitting in alkaline media are accomplished by constructing bushy Cu nanowires on Cu foam to support cobalt phosphide nanosheets (Co–P/Cu NWs/CF). Results demonstrate that the highly efficient electroactivity of Co–P/Cu NWs/CF originates from the high intrinsic activity of Co–P species, Cu nanowires which possess accessible active sites, plentiful bubbles releasing channels, and honored electric conductivity, as well as the interaction between Cu NWs and Co–P species. To achieve a current density of 200 mA cm−2, Co–P/Cu NWs/CF require an overpotential of only 155 mV for hydrogen evolution and 349 mV for oxygen evolution, which are less than that of Co–P/Cu(OH)2 NWs/CF and Co–P/CF. This work provides a simple and efficient approach to designing water splitting electrocatalysts by manufacturing nanostructure-rich conductive substrates to support active species.

Sliver nanoparticles decorated Co-Mo nitride for efficient water splitting

Designing highly active and robust bifunctional electrocatalysts toward efficient overall water splitting using for novel renewable energy storage and conversion systems is still a challenging task. Here, self-supported bimetallic cobalt-molybdenum nitride with silver nanoparticles decoration (Co-Mo-N@Ag) growth in situ on carbon paper was rationally designed and fabricated for overall water splitting in alkaline media. By virtue of the admirable compositional and structural advantages of exposed enough active sites, regulated favorable electronic structure, and engineered powerful interface synergy effect, the Co-Mo-N@Ag electrode exhibits superior electrocatalytic performance in 1 M KOH. In the details, an excellent oxygen evolution reaction (OER) activity with an extremely low overpotential of 234 mV at 10 mA cm−2 and a small Tafel slope of 54 mV dec-1, as well as a remarkable hydrogen evolution reaction (HER) activity with a low overpotential of 90 mV at 10 mA cm−2 and Tafel slope of 73 mV dec-1 were acquired by Co-Mo-N@Ag. As a result, it takes a low voltage of 1.56 V to reach 10 mA cm−2 in alkaline overall water splitting. This work presents the heterogeneous interfacial structure decorated by silver and provides a feasible method to increase the OER and HER activity of metal nitrides.

Highly efficient oxygen evolution and stable water splitting by coupling NiFe LDH with metal phosphides

It is a great challenge to develop highly active oxygen evolution reaction (OER) electrocatalysts with superior durability. In this study, a NiFe layered double hydroxide-decorated phosphide (NiFe LDH@CoP/NiP3) was constructed to display satisfactory OER activity and good stability for water splitting in alkaline media. At an overpotential of 300 mV, NiFe LDH@CoP/NiP3 achieved a current density of 82 mA cm−2 for the OER, which was 9.1 and 2.3 times that of CoP/NiP3 and NiFe LDH, respectively. Moreover, the reconstruction behavior, during which oxyhydroxides formed, was studied by a combination of X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron microscopy. A synergistic effect between NiFe LDH and CoP/NiP3 was also observed for the hydrogen evolution reaction. Furthermore, when NiFe LDH@CoP/NiP3 acted as both the cathode and anode for overall water splitting, a high current density of 100 mA cm−2 was maintained for more than 275 h. In addition, under Xe light irradiation, a solar to hydrogen efficiency of 9.89% was achieved for solar-driven water splitting. This work presents the coupling of different active compositions, and can provide a reference for designing bifunctional electrocatalysts.

Efficient electrocatalytic overall water splitting and structural evolution of cobalt iron selenide by one-step electrodeposition

Fe-incorporated dual-metal selenide on nickel foam (Co 0.9 Fe 0.1 -Se/NF) with superior and stable electrocatalytic overall water splitting performance in alkaline media is synthesized by a facile one-step electrodeposition method. Developing bifunctional electrocatalysts with both high catalytic activity and high stability is crucial for efficient water splitting in alkaline media. Herein, a Fe-incorporated dual-metal selenide on nickel foam (Co 0.9 Fe 0.1 -Se/NF) is synthesized via a facile one-step electrodeposition method. As-synthesized materials could serve as self-supported bifunctional electrocatalysts with excellent catalytic activity towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media. Experimental results show that delivering a 10 mA cm −2 water splitting current density only requires a cell voltage of 1.55 V. In addition, a very stable performance could be kept for about 36 hours, indicating their excellent working stability. Moreover, by means of phase analysis, we have identified that the evolution of the synthesized Co 0.9 Fe 0.1 -Se/NF experiences two entirely different processes in HER and OER, which hydroxide and oxyhydroxide are regarded as the real active sites, respectively. This work may pave the way to further understanding the relationships between the reactivity and stability of chalcogenide-based electrocatalysts and facilitating the rational design of efficient electrocatalysts for future renewable energy system applications.

Flocculent VS nanoparticle aggregate-modified NiCo2S4 nanograss arrays for electrocatalytic water splitting

Flocculent VS nanoparticle aggregate-modified NiCo2S4 nanorod arrays grown on a nickel foam as a electrocatalyst exhibited superior electrocatalytic performance for overall water splitting in alkaline media.

Cobalt and nitrogen co-doped Ni3S2 nanoflowers on nickel foam as high-efficiency electrocatalysts for overall water splitting in alkaline media.

The development of high-performance and cost-effective bifunctional water splitting catalysts has enormous significance in the hydrogen production industry from water electrolysis. Herein, an in situ Co and N co-doping method was developed to improve the electrocatalytic performance of Ni3S2 catalysts. The Co-N-Ni3S2/NF is successfully synthesized for the first time by a one-step hydrothermal method, wherein nickel foam, thioacetamide and Co(NO3)2·6H2O are used as the nickel source, sulfur source, nitrogen source and cobalt source. Co-N-Ni3S2/NF exhibits excellent oxygen evolution reaction activity (an overpotential of 285 mV@50 mA cm-2) and hydrogen evolution reaction activity (an overpotential of 215 mV@10 mA cm-2) in 1 M KOH solution. The electrolytic cell displayed a low cell voltage of 1.50 V when the Co-N-Ni3S2/NF material was used as the bifunctional water splitting electrocatalyst, which is one of the best catalysts reported so far. Density functional theory calculations show that Co-N-Ni3S2/NF exhibits stronger water adsorption energy than those of N-Ni3S2/NF, Co-Ni3S2/NF and Ni3S2/NF. It is proved that the doping of Co and N can effectively regulate the electron cloud density of Ni, thus enhancing the electrochemical activity of Co-N-Ni3S2/NF.

Active site and intermediate modulation of 3D CoSe2 nanosheet array on Ni foam by Mo doping for high-efficiency overall water splitting in alkaline media

The active site and intermediate modulation effect of Mo doping remarkably boosted the bifunctional electrocatalytic performances of the 3D Mo-CoSe 2 NS@NF electrode with a low overpotential of 89 and 234 mV at a current density of 10 mA cm −2 for HER and OER in alkaline media, respectively. • 3D Mo-doped porous CoSe 2 nanosheets were directly formed on the commercial Ni foam. • Mo doping modulated intermediate adsorption energy and active sites. • The Mo-CoSe 2 NS@NF based water splitting showed high-efficiency and excellent stability. The recently emerging renewable energy industry has boosted a research hot in searching for bifunctional electrocatalysts for water splitting. CoSe 2 , as one of transition-metal chalcogenides, has attracted particular attention because of its abundant resource, low cost, high efficiency and stability. However, further enhancing catalytic activity of CoSe 2 to meet the large-scale application requirements of hydrogen energy remains an important challenge. Herein, three-dimension (3D) Mo-doped porous CoSe 2 nanosheet array was directly formed on commercial Ni foam (Mo-CoSe 2 NS@NF) electrode through a three-step process including electrodeposition, hydrothermal and subsequent selenylation. Systematically experimental research and density functional theory calculations confirmed that, based on active site and intermediate modulation effect of Mo doping, the obtained 3D Mo-CoSe 2 NS@NF electrodes were provided with enlarged electrochemical active surface area, improved charge transport capability and significantly optimized binding energy for active intermediates of the potential-limiting step, thus exhibiting remarkably boosted bifunctional electrocatalytic ability with a low overpotential of 89 and 234 mV to drive a current density of 10 mA cm −2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, respectively. When the Mo-CoSe 2 NS@NF electrode was employed as both a cathode and an anode, an advanced water electrolyzer was fabricated, and a 10 mA cm −2 water splitting current density in 1 M KOH solution could be acquired at a minimal cell voltage of 1.54 V. In addition, we also inferred that the active surface for the OER was O* covered CoSe 2 , and OER occurred through direct recombination mechanism according to the present first-principles simulation. This work offers an atomistic understanding on the boosted HER and OER electrocatalytical activity of CoSe 2 by Mo doping, and develops a promising strategy for exploring advanced low-cost and earth-abundant water splitting electrocatalysts to substitute for the precious-metallic catalysts as well.

CoP@NC electrocatalyst promotes hydrogen and oxygen productions for overall water splitting in alkaline media

Design and synthesis of high-performance bi-functional electrocatalysts can play a crucial role for electrolytic water splitting. Herein, we develop a simple phosphating process to construct cobalt phosphide@nitrogen-doped carbon (CoP@NC) using metal organic frame (MOF) as a precursor and a template. In alkaline solution, CoP@NC-350 exhibits exceptional hydrogen and oxygen evolution reaction performances with over potentials of 75 mV and 268 mV at 10 mA cm−2, respectively. For a symmetric CoP@NC-350 two-electrode water splitting setup, the potential can be low as 1.69 V to obtain 10 mA cm−2. Therefore, low-temperature phosphating treatment can be a simple and promising method to produce electrocatalysts for water splitting.

Controllable design of nanoworm-like nickel sulfides for efficient electrochemical water splitting in alkaline media

Developing cost-effective electrocatalysts for electrochemical water splitting (EWS) is appealing and challenging for sustainable water electrolysis. Currently, nickel sulfides are considered as promising candidates for EWS due to their low cost and high catalytic activity. However, the facile design of nickel sulfides with high catalytic performance is still highly demanded. In this study, we have developed a one-step solvothermal strategy to construct nickel sulfides as efficient water splitting catalysts. By taking advantage of the small size, abundant active sites, large electrochemical surface area, and good conductivity, the nanoworm-like nickel sulfides (NiS-NW/Ni foam [NF]) exhibit better oxygen evolution reaction performance (a low overpotential of 279 mV to achieve 100 mA cm−2, Tafel slope of 38.44 mV dce−1) than the nanoplate-like analogs, as well as most of reported nickel sulfide–based electrocatalysts. In addition, the NiS-NW/NF directly used as bifunctional electrodes for overall water splitting requires a low voltage of 1.563 V to attain a current density of 10 mA cm−2 with good long-term durability. This work provides a facile strategy for the design of efficient nickel sulfide-based electrocatalysts for energy conversion applications.

Electrodeposition of Ir–Co thin films on copper foam as high-performance electrocatalysts for efficient water splitting in alkaline medium

Iridium-based bimetallic alloy system with unique performance is of great interest for high-temperature corrosive environment as a barrier layer or for water splitting of hydrogen/oxygen evolution reactions as a highly efficient and stable electrocatalyst. In this work, iridium-cobalt (Ir–Co) thin films were galvanostatically electrodeposited on a copper (Cu) foam electrode as an electrocatalyst for water splitting in 1.0 M KOH alkaline medium. The effects of loading and solution temperature on hydrogen evolution performance of Ir–Co deposits were investigated. The results show that Ir–Co deposits were adhered to substrates, with porous structure and hollow topography. The concentrations of Ir in the deposits with the loadings of 4.6, 3.2 and 0.8 mg·cm−2 were 88, 88 and 75 wt%, respectively. Ir–Co deposit with the loading of 3.2 mg·cm−2 required an overpotential of 108 mV for hydrogen evolution reaction to reach a current density of 30 mA cm−2, having a low Tafel slope value of 36 mV·dec−1. The changes in the solution temperature and catalyst loading had a significant effect on hydrogen evolution performance of Ir–Co/Ir–Co–O electrocatalysts. With the increasing of catalyst loading, the electrocatalytic activity increased firstly and then decreased. As the solution temperature was increased from 20 to 40 °C, the electrocatalytic activity of Ir–Co–O electrocatalyst increased, and then decreased with the rising of temperature. The apparent thermal activation energy obtained from Arrhenius plot was ~13.9 kJ mol−1. Ir–Co/Ir–Co–O deposits exhibited relatively good electrocatalytic stability and durability. The present work demonstrates a possible pathway to develop a highly active and durable substitute for thin film electrocatalysts for water splitting of hydrogen evolution reaction.

Trimetallic MOF-74 Films Grown on Ni Foam as Bifunctional Electrocatalysts for Overall Water Splitting.

Developing earth-abundant and high-performance electrocatalysts for water splitting has long been a vital research in energy conversion field. Herein, we report the preparation of a series of trimetallic uniform Mnx Fey Ni-MOF-74 films in-situ grown on nickel foam, which can be utilized as bifunctional electrocatalysts towards overall water splitting in alkaline media. The introduction of Mn can simultaneously regulate the morphology of MOF-74 to form uniform film and modulate electronic structure of Fe to form more Fe(II)-O-Fe(III) motifs, which is conducive to the exposure of active sites and stabilizing high-valent metal sites. The optimized Mn0.52 Fe0.71 Ni-MOF-74 film electrode showed excellent electrocatalytic performance, affording a current density of 10 mA ⋅ cm-2 at an overpotential of 99 mV for HER and 100 mA ⋅ cm-2 at an overpotential of 267 mV for OER, respectively. Assembled as an electrolyser, Mn0.52 Fe0.71 Ni-MOF-74 film electrode exhibited excellent performance towards overall water splitting, with ultralow overpotential of 245 and 462 mV to achieve current density of 10 and 100 mA ⋅ cm-2 , respectively. This work provides a new view to develop multi-metal MOF-based electrocatalysts.

Nickel foam-supported Fe,Ni-Polyporphyrin microparticles: Efficient bifunctional catalysts for overall water splitting in alkaline media

Developing highly active, stable and sustainable electrocatalysts for overall water splitting is of great importance to generate renewable H2 for fuel cells. Herein, we report the synthesis of electrocatalytically active, nickel foam-supported, spherical core-shell Fe-poly(tetraphenylporphyrin)/Ni-poly(tetraphenylporphyrin) microparticles (FeTPP@NiTPP/NF). We also show that FeTPP@NiTPP/NF exhibits efficient bifunctional electrocatalytic properties toward both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Electrochemical tests in KOH solution (1 M) reveal that FeTPP@NiTPP/NF electrocatalyzes the OER with 100 mA cm−2 at an overpotential of 302 mV and the HER with 10 mA cm−2 at an overpotential of 170 mV. Notably also, its catalytic performance for OER is better than that of RuO2, the benchmark OER catalyst. Although its catalytic activity for HER is slightly lower than that of Pt/C (the benchmark HER electrocatalyst), it shows greater stability than the latter during the reaction. The material also exhibits electrocatalytic activity for overall water splitting reaction at a current density of 10 mA cm−2 with a cell voltage of 1.58 V, along with a good recovery property. Additionally, the work demonstrates a new synthetic strategy to an efficient, noble metal-free-coordinated covalent organic framework (COF)-based, bifunctional electrocatalyst for water splitting.

Active Sites of Single-Atom Iron Catalyst for Electrochemical Hydrogen Evolution.

Electrochemical water splitting in alkaline media is an attractive way to produce the clear and renewable hydrogen fuel H2. In this work, we report a single-atom Fe1/NC catalyst, where the Fe-Nx moiety works as the active site, for high-efficiency alkaline hydrogen evolution reaction (HER). The Fe1/NC electrocatalyst exhibits a low overpotential of 111 mV at the current density of 10 mA cm-2, with a Tafel slope of 86.1 mV dec-1 in 1 M KOH solution. Operando X-ray absorption spectroscopy reveals that, under the working states, the Fe-support interaction weakened as the Fe-N coordination number and Fe oxidation state decreased. As such, the evolved single-atom Fe site with more d electrons provides a favorable structure for boosting HER performance. This work gives insight into the structural evolution of the active site under the alkaline HER and provides a strategy for the design of non-noble metal electrocatalysts.

Hydrophilic Ni(OH)2@CoB nano-chains with shell-core structure as an efficient catalyst for oxygen evolution reaction

Enormously active and cost-effective electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are the critical components to produce hydrogen via water splitting using the electricity produced from renewable energy sources. Herein, inspired by the highly electric conductivity of CoB, shell-core structured Ni(OH)2@CoB nano-chains are synthesized as highly active OER catalyst with the assistance of the magnetic field. In the shell-core structured Ni(OH)2@CoB nano-chains, Ni(OH)2 nanoflakes were directly grown onto CoB nano-chains via a facile and wet chemical method. Ni(OH)2 in nanoflake form can provide more available active sites on the surface for electrochemical reaction that is evidenced by high BET surface area (648.9 m2 g−1). At the current density of 10 mA cm−2, the overpotentials of OER occurred on Ni(OH)2@CoB is 320 mV. The obtained Ni(OH)2@CoB also shows very good OER durability without any observable decline for 12 h. The high OER catalytic performance combined with its low-cost makes the Ni(OH)2@CoB nano-chains promising OER catalyst for water splitting in alkaline media.

Cobalt-stabilized oxygen vacancy of V2O5 nanosheet arrays with delocalized valence electron for alkaline water splitting

Stabilizing oxygen vacancy for oxides-based electrocatalysts is the most challenging to achieve high-efficient overall water splitting in alkaline media. Herein, the oxygen vacancy (OV) engineered V2O5 nanosheet arrays have been demonstrated as bifunctional electrocatalysts, in which cobalt ions are utilized to tailor OV content and keep steady. The maxmized OV engineering can render the valance electrons shift to higher binding energy with moderate surface chemical states, optimizing H* adsorption on vanadium center at the electrochemical interface. Consequently, a superlow overpotential of 51 mV is required to attain a current density of 10 mA cm−2 for hydrogen evolution with 24 h durable stability. The corresponding overpotential is about 277 mV for oxygen evolution. After assembling a two-electrode electrolyzer, it shows a very low voltage of 1.55 V at 10 mA cm−2. This work provides a viable cationic induced OV formation strategy for oxides-based electrocatalysts to obtain satisfied catalytic activity and stability.

Efficient multifunctional electrocatalyst based on 2D semiconductive bimetallic metal-organic framework toward non-Pt methanol oxidation and overall water splitting

As the efficient approaches for obtaining clean H2 energy, methanol oxidation (MOR) and water over slitting reactions have been increasingly essential. A series of novel semiconductive CoNi bimetal–organic framework (CoxNi3-x(HAB)2 MOF) have been prepared using hexaaminobenzene (HAB) as an organic linker. The obtained series of CoxNi3-x(HAB)2 MOFs were then explored as efficient multifunctional electrocatalysts for the non-Pt MOR and overall water splitting in alkaline medium. The basic characterizations of CoxNi3-x(HAB)2 MOFs revealed that they comprised multiple metal valence states (Co0/Co2+/Co3+ and Ni2+/Ni3+) and graphene-like nanostructures embedded with abundant CoNi alloy nanoparticles. Compared with the sole-metal MOFs (Co3(HAB)2 MOF and Ni3(HAB)2 MOF), the CoxNi3-x(HAB)2 MOF with a mass ratio of Co:Ni = 1:3 (CoxNi3-x(HAB)2 MOF-2) exhibited superior electrocatalytic performance for MOR. It gave a high current density of 92.8 mA cm−2 at 1.6 V vs. reversible hydrogen electrode (RHE) for MOR, along with the low overpotentials at the current density of 10 mV cm−2 (η10) and Tafel slopes toward hydrogen evolution reaction (η10 = 119 mV, Tafel slope = 46 mV dec-1) and oxygen evolution reaction (η10 = 1.35 V, Tafel slope = 26 mV dec−1). The analysis on the catalysis mechanism of MOR and water splitting in alkaline medium was also proposed. The voltages applied to the three- and two-electrode systems based on the bifunctional CoxNi3-x(HAB)2 MOF-2 catalyst for overall water splitting are 1.52 V vs. RHE and 1.45 V vs. silver/silver chloride (Ag/AgCl), respectively. This work provides a novel strategy for investigating the applications of promising two-dimensional semiconductive MOF as multifunctional electrocatalysts with boosted electrocatalytic activities in energy fields.