Engineering the semiconducting CdS nanostructures by N-doped rGO for enhancing the adsorption sites: Promising electrocatalyst for hydrogen evolution reaction

The development of non-noble electrocatalysts for hydrogen production from water is of immense interest as it is clean and eco-friendly. The present work explores the electrocatalytic performance of morphologically varied CdS NPs synthesized using different sulphur source and ionic liquids via hydrothermal treatment, in catalyzing hydrogen evolution reaction (HER). The hierarchical flower shaped morphology denoted as CdS–N3 outperformed other prepared electrocatalysts with a Tafel slope value of 118 mV dec^?1 and a low overpotential 344 mV @ a current density of 10 mA/cm². However, the outperformed CdS–N3 catalyst when blended with N doped rGO, it showed a superior activity with a low overpotential of 201 mV at 10 mA/cm². The catalyst disclosed a small Tafel slope of 70 mV dec^?1 corroborating that the catalyst contains more electroactive sites and oxygen vacancy voids for the adsorption-desorption of charge carriers generated from the heteroatom doping. The CdS/N-rGO catalyst also revealed a higher TOF value of 5.18 × 10^?3 s^?1, which further proves that catalyst is more efficient in releasing H₂ molecules and this findings affirms that CdS/N-rGO catalyst can be an efficient candidate for initiating HER kinetics with endurable stability in acidic medium for high purity hydrogen production.     

Hexagonal CoSe2 nanosheets stabilized by nitrogen-doped reduced graphene oxide for efficient hydrogen evolution reaction

CoSe₂ is considered as a promising candidate among non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) due to its intrinsic metallicity and low Gibbs free energy for hydrogen adsorption. Recently, the hexagonal CoSe₂ becoming increasingly popular owing to its chemically favorable basal plane, which provides more active sites, but remains limited by the poor stability. In this study, we design a small-molecule-amine-assisted hydrothermal method to in situ anchor the hexagonal CoSe₂ nanosheets (NSs) on nitrogen-doped reduced graphene oxides (RGO) as an advanced electrode material for HER. Due to the existence of abundant functional groups and high specific surface area of RGO, the hexagonal CoSe₂ NSs could be stably formed on RGO. As a result, only a small overpotential of 172 mV is needed for the optimized sample to drive a current density of 10 mA cm⁻² in 0.5 M H₂SO₄ and the Tafel slope is 35.2 mV dec⁻¹, which is comparable with the state-of-the-art Pt catalyst (32.3 mV dec⁻¹). Therefore, the facile and low-cost method for synthesizing hexagonal TMDs with robust electrical and chemical coupling developed in this work is promising in promoting the large-scale application of non-precious electrocatalysts.     

Phosphorus-doped nickel selenides nanosheet arrays as highly efficient electrocatalysts for alkaline hydrogen evolution

Earth-abundant transition-metal dichalcogenides are considered as promising electrocatalysts to accelerate the hydrogen evolution reaction （HER）. Among them, the pyrite nickel diselenide (NiSe₂) has been received special attention due to its low cost and high conductivity, but it suffers a poor HER performance in alkaline media possibly attributed to its inadequate hydrogen adsorption free energies. Here, we report a novel P-doped NiSe₂ nanosheet arrays anchored on the carbon cloth with an obviously optimized HER performance. The catalyst only needs a low overpotential of 86 mV at a current density of 10 mA cm^?2 and a Tafel slop of 61.3 mV dec^?1，as well as maintains a long-term durability for 55 h in 1.0 M KOH, which is superior to the pristine NiSe₂ (135 mV@10 mA cm^?2) and most recently reported non-noble metal electrocatalysts. The XRD, EDS, TEM and XPS results validated the successful doping of P element into NiSe₂ nanosheet, while the density functional theory (DFT) calculation demonstrated the P doping can optimize the electronic structures and the hydrogen adsorption free energy of NiSe₂. This work thus opens up new ways for rationally designing high-efficient HER electrocatalysts and beyond.     

Ruthenium-manganese phosphide nanohybrid supported on graphene for efficient hydrogen evolution reaction in acid and alkaline conditions

Transition metal phosphides (TMPs) have been proved to be promising, economical and effective catalysts for hydrogen evolution reaction (HER). Precious metals with transition metals alloying can appropriately adjust the adsorption energy, which is an effective solution for greatly reducing the cost of noble metal catalysts and improving their inherent performance. Herein, a simple method was employed to synthesize MnRuPOGO-500 nano-catalysts with a particle size of about 5 nm, which showed excellent HER performance under both acid and basic media. In acidic solution, the optimal catalyst displayed the overpotential of HER to reach 10 mA cm^?2 with 109 mV, a small Tafel slope of 38.55 mV dec^?1 and long-time durability of 60 h. Especially in alkaline medium, the low overvoltage of 27 mV, a small Tafel slope of 57.35 mV dec^?1 and continuing stability of 48 h were further achieved. Meanwhile, we can find that manganese has negligible HER activity, but the doping of manganese generates a synergistic modulation effect in the MnP–Ru₂P alloy, thereby improving the HER performance of the catalyst. This paper brings a simple scheme and unique insights to the design of transition metals and platinum group metals (PGMs) phosphide alloy electrocatalysts.     

Interface regulation of Pt quantum dots doped nickel phosphide and cobalt hydroxide to promote electrocatalytic overall water splitting

The transition metal phosphates are earth-abundant minerals that have been shown to perform well in electrocatalytic water splitting, whereas these catalysts still tend to have excessively high overpotentials and slow kinetics in HER and OER processes. In the present work, hybrid catalysts consisting of Pt quantum dots doped NiP (NiP-Pt) nano-embroidery spheres and Co(OH)₂ nanosheets were successfully prepared by two-step electrodeposition method. The excellent catalytic performance of the catalyst relies principally on the synergistic interaction between NiP and Pt quantum dots. Additionally, the NiP-Pt exhibits strong electronic interactions at the interface with Co(OH)₂. Consequently, the catalyst has a strong catalytic performance in terms of HER and OER catalytic performance. In terms of HER, an overpotential of only 40 mV is required when the current density reaches 10 mA cm^?2, corresponding to a Tafel slope of 49.85 mV·dec^?1. At the same time, the catalyst also performs well at OER, with a current density of 10 mA cm^?2 at an overpotential of 186 mV and a Tafel slope of 53.049 mV·dec^?1 much less than most electrocatalysts. This study involving electrodeposition and doping of quantum dots provides a new idea for the efficient synthesis of fundamental HER and OER bifunctional catalysts.     

Self-supported molybdenum selenide nanosheets grown on urchin-like cobalt selenide nanowires array for efficient hydrogen evolution

The development of a highly efficient hybrid catalyst is desirable for the water splitting to produce hydrogen. MoSe₂ is one of the low-cost candidates; however, its activity for hydrogen evolution reaction (HER) is still not satisfactory due to the low conductivity and poor electrical contact with the charge collection substrate. Herein, we provide a simple approach of synthesizing vertically aligned MoSe₂ nanoplatelets on the urchin-like HER-active conductive CoSe₂ nanowire array. Nanostructured MoSe₂/CoSe₂ hybrid catalysts obtained a current density of 10 mA cm⁻² at overpotentials of only 129 mV, with a small Tafel slope of 38.2 mV dec⁻¹, which is superior to those of most transition metal dichalcogenides (MoSe₂, MoSe₂–CoSe₂ hybrids, and so on). The abundant exposed active sites of MoSe₂, as well as an efficient electrical contact between MoSe₂ nanosheets and CoSe₂ nanowires, which is beneficial for the outstanding HER performance of MoSe₂/CoSe₂ hybrid electrode.     

Fe-doped NiCo2S4 catalyst derived from ZIF – 67 towards efficient hydrogen evolution reaction

The development of economical, efficient and stable non-noble metal catalysts plays a key role in electrocatalytic hydrogen evolution. NiCo₂S₄ has been proved to be an efficient non-noble catalyst, to further improve its electrocatalytic performance is a meaningful work. In this paper, the effects of Fe doping on electrochemical performance of NiCo₂S₄ is investigated. The Fe-doped NiCo₂S₄ catalyst is prepared by a facile solvothermal method with metal-organic-framework (MOF, ZIF-67) as template, and it exhibits an improved hydrogen evolution reaction (HER) performance with an overpotential of 181 mV at 10 mA cm^?2, a Tafel slope of 125 mV dec^?1 compared with that of NiCo₂S₄ (252 mV overpotential and 149 mV dec^?1 Tafel slope). The combination of improved conductivity, mesopores architecture retained with the ZIF-67 template, which result the reduced internal resistance, enhanced charge transportation as well as large electrochemical double-layer capacitance. This work provides an effective and synergistic strategy for fabricating NiCo₂S₄-based catalysts toward electrochemical water splitting.     

Trace amounts of palladium-doped hollow TiO2 nanosphere as highly efficient electrocatalyst for hydrogen evolution reaction

Hollow titanium dioxide (TiO₂–H) sphere and Pd@TiO₂–H core-shell were successfully synthesized through hydrothermal method, and their electrocatalytic properties for hydrogen evolution reaction (HER) were evaluated The 0.05 wt%Pd@TiO₂–H achieved the lowest overpotential of 0.43V at 10 mA cm^?2 with a Tafer slope of 63 mV dec^?1, which were both apparently outperforming than that of the commercial TiO₂ (0.92 V, 636 mV dec^?1). Electrochemical stability was also confirmed by a negligible attenuation for polarization curves before and after 5000 cycles. The attractive performance can be attributed to the special hollow structural and Pd doping effect resulting in the increased amount of active sites. This study provides a special material to develop lower cost, more stable and efficient titanium oxide based electrocatalysts for HER.     

Exposure of active sites in Mn–SnS2 nanosheets to boost hydrogen evolution reaction

Designing and synthesizing high-activity, durable, and low-cost catalysts for the electrochemically transformation of water to hydrogen are vitally important to future energy systems. Herein, a simple but effective strategy for manganese-metal-heteroatom doping is adopted to intrinsically elevate the electrocatalytic activities of SnS₂ nanosheets by a facile two steps hydrothermal-sulfurization approach. Electrocatalytic hydrogen evolution (HER) performance of Mn–SnS₂ nanosheets grown on 3D nickel foam (Mn–SnS₂/NF) is efficiently optimized since the dopants and defects endow the Mn–SnS₂/NF vast active sites. An overpotential as low as 71 mV is required to drive a current density of 10 mA/cm² with a low Tafel slope of 72 mV dec^?1 in alkaline environment (1 M KOH). In addition, the Mn–SnS₂/NF exhibits prominent stability in 1 M KOH electrolyte, which is an indispensable index for the potential HER electrocatalysts. The present work demonstrates that the heteroatom manganese doping strategy renders a meaningful route for synthesizing cost-efficient HER electrocatalysts in alkaline condition.     

Mo2C regulated by cobalt components doping in N-doped hollow carbon nanofibers as an efficient electrocatalyst for hydrogen evolution reaction

Hydrogen is a viable substitute to fossil fuels and electrochemically catalyzed hydrogen evolution has attracted wide attention due to its stability and effectiveness. Nevertheless it is still a major challenge to design and prepare highly active noble metal-free electrocatalysts with controllable structure and composition for efficient hydrogen evolution reaction (HER). Herein, Mo₂C regulated by cobalt components (Co and CoO) doping in N-doped hollow carbon nanofibers (marked as Mo₂C/Co/CoO-NHCNFs) are firstly designed and prepared via a facile coaxial electrospinning followed by calcination process. The one-dimensional conductive carbon host, hollow structure and synergistic effect among CoO, Co and Mo₂C can jointly promote electron transfer, augment exposure of active sites and adjust the electronic structure of the active sites, resulting in the excellent of HER performances. The optimized catalyst has a high specific surface area of 101.27 m² g^?1. Meanwhile, it has a low overpotential of 143 mV at a current density of 10 mA cm^?2 and a small Tafel slope of 74 mV dec^?1 in 1.0 M KOH.Satisfactorily, the overpotential is reduced by 231 mV at the same current density compared with Mo₂C doped in N-doped carbon nanofibers (named as Mo₂C-NCNFs). Moreover, the Mo₂C/Co/CoO-NHCNFs also demonstrate superior long-term stability. The formative mechanism of Mo₂C/Co/CoO-NHCNFs is expounded, and the construction technique is established. The design philosophy and the simple and economical method are of significance for development of HER electrocatalysts.     

Carbon nanorod supported metal alloy nanocubes using polydopamine as location reagent for water splitting

Transition metal catalysts were supposed to be the most likely substitute for commercial noble metal catalysts, and the development of highly active and long-term catalyst for water splitting are the future trend. Herein, Ni rectangular nitrogen doped carbon nanorods@Fe–Co nanocubes (Ni-CNRs@Fe–Co cubes) were fabricated via a facile template-free method. This simple strategy not only realizes the structure tailoring, but also achieves high-quality nitrogen-doping. Specifically, nickel dimethylglyoxime [Ni(dmg)₂] with rectangular rodlike structure was firstly synthesized by solution method, then metal-organic frameworks Fe–Co nanocube with different contents were loaded on rectangular carbon nanorods with polydopamine as the locating and the connecting agent, and finally Ni-CNRs@xFe-Co cubes were obtained by a one-step calcination. A series of electrochemical tests were researched on materials with different metal contents in the 1 M KOH solution. The Ni-CNRs@Fe–Co cubes show excellent electrocatalytic activity in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). For HER and OER, the Tafel slopes were 83.3 mV dec⁻¹ and 71 mV dec⁻¹, the onset potential were −167 mV and 1.62 V, and reached the current densities of 10 mA cm⁻², the overpotential just needed 196 mV and 433 mV, respectively. This novel synthetic strategy will provide a template-free way for cheap electrocatalysts of non-precious metal for OER and HER.     

CoSe2 nanocrystals embedded into carbon support as coralline-like catalysts for hydrogen evolution reaction

It is vital to develop a high activity, stability and inexpensive hydrogen evolution reaction (HER) catalyst for electrochemical hydrogen evolution. A high-temperature reaction approach that is Co nanocrystals on carbon support (XC-72R) and selenylation to synthetize CoSe₂/C nanocrystals is used, and the effect of temperature on CoSe₂/C nanocrystals is studied. The morphology and catalytic properties of CoSe₂/C nanocrystals annealed at different temperatures are compared in 0.5 M H₂SO₄. The results indicated the coralline-like CoSe₂/C-650 nanocrystals have a high performance for HER with Tafel slopes of 45.73 mV·dec⁻¹ and onset potential of −196 mV vs. RHE. The stability maintained for at least 40 h and the Faraday Efficiency (FE) of H₂ is nearly 98%. The outstanding HER performance of CoSe₂/C-650 is due to its characteristic cora-like frame CoSe₂ nanocrystals embedded into supernal conductive XC-72R, which not only offer affluent active reaction sites, but also boost the capacity of charge transportation in HER process.     

Cobalt sulfide nanoparticles supported on beryllium copper needles as advanced catalysts for hydrogen evolution reaction

Non-precious transition metal electrocatalysts, which have excellent catalytic performance and cheap cost, enable developable and sustainable hydrogen production via water separation. Cobalt-based transition metal compounds, especially sulfide, are the most efficient and stable electrocatalysts of them. In this work, we report a CoS nanoparticles array on beryllium copper needles as a high potency electrocatalyst in basic electrolyte. Owing to the excellent electron transfer capability of beryllium copper needles, the as-prepared catalyst is effective in catalyzing hydrogen evolution reaction (HER) with the overpotential of 73 mV, to achieve the current density of 10 mA cm^?2 and can maintain excellent performance. Correspondingly, the Tafel slope of the electrode reaction is 76 mV dec^?1. In addition, the electrode also shows good durability and stability, which is reflected in a small decrease in activity after 5000 CV (Cyclic Voltammetry) cycles and almost no decay after 30 h of electrolysis. This work demonstrates its potential for practical applications in efficient hydrogen production.     

2D MoSe2/CoP intercalated nanosheets for efficient electrocatalytic hydrogen production

Low-dimensional transition metal dichalcogenides, e.g., MoSe₂, are attractive electrocatalysts for hydrogen evolution reactions (HER). However, the stable 2H-phase MoSe₂ with semiconducting properties exhibits electrocatalytic performance only at its sheet edges, but the basal planes without defects are inactive, limiting their performance in HER. This work reported a strategy for comprehensive activation of TMDs by intercalating 2D MoSe₂ with 2D CoP. Its unique sandwiched structure opens up activity between the layers, enhancing active surface area to 10-fold. Meanwhile, the maximized interfaces enable rapid ion/electron transport and excellent electrical conductivity, thus yielding superior HER activity. It exhibits a very low overpotential of 105 mV at 10 mA cm⁻², small Tafel slope of 51 mV dec⁻¹ and excellent electrochemical stability for >24 h. The CoP significantly increases the hydrogen adsorption sites of MoSe₂ in the basal planes, and the P atoms enable Mo and Co atoms adjacent to them become the most active ones, according to Density Functional Theory calculations. Our work, using two layered materials as precursors to intercalate with each other, provides new ideas for designing efficient and non-precious metal electrocatalysts. Moreover, this method can be universally applicable to synthesize other hybrid materials such as CoSe₂/MoSe₂, FeP/MoSe₂, NiP/MoSe₂, CoSe₂/WS₂, FeP/TiS₂ and so on.     

Boosting activity and stability by coupling Pt–Ni nanoparticles with La-modified flexible carbon nanofibers for hydrogen evolution reaction

Platinum (Pt) is considered as the most efficient catalyst for hydrogen evolution reaction (HER) with a nearly zero overpotential, but it is limited by the high cost and poor stability. Herein, we report an efficient electrocatalyst of Pt–Ni alloy nanoparticles (NPs) supported on the La-modified flexible carbon nanocomposite fibers (PtNi@La-CNFs) for HER. The rare earth metal oxide in the catalyst has a structure-effect relationship with the carbon fibers to form a flexible fiber membrane. Experimental results show that the macroscopic and microscopic properties of carbon nanocomposite fibers can be optimized by doping La₂O₃, and the Pt–Ni NPs can be anchored effectively. The Pt₁Ni₁@La-CNFs electrocatalyst exhibits a small overpotential of 32 mV to achieve current density of 10 mA cm^?2 with a low Tafel slope of 51 mV dec^?1 in alkaline medium, outperforming that of Pt@La-CNFs and the commercial Pt/C catalyst. This study reveals that the multiple coupling effect of rare earth compound, precious metal, and transition metal in composite catalyst can tailor its the electronic configuration, and results in an enhanced HER performance. This work opens up a novel approach to design high active and low cost Pt-based HER catalysts.     

Hollow hexagonal NiSe–Ni3Se2 anchored onto reduced graphene oxide as efficient electrocatalysts for hydrogen evolution in wide-pH range

Integrating transition metal complexes with carbon-based materials, especially graphene, is a useful strategy for synthesizing effective hydrogen evolution catalysts. Herein, we report a design of hollow hexagonal NiSe–Ni₃Se₂ nanosheets grown on reduced graphene oxide (NiSe–Ni₃Se₂/rGO) by a simple hydrothermal method as an effective catalyst for hydrogen evolution reaction (HER) in the full pH range. In 0.5 M H₂SO₄, the NiSe–Ni₃Se₂/rGO possesses 112 mV to achieve 10 mA cm^?2 and a small Tafel slope (61 mV dec^?1). In 1.0 M PBS and 1.0 M KOH, the overpotentials are 261 and 188 mV at 10 mA cm^?2, and Tafel slopes are 103 and 92 mV dec^?1, respectively. Meanwhile, it owns good cycle stability and durability over 20 h in the whole pH range (0-14). In all solutions, the HER performance of NiSe–Ni₃Se₂/rGO is better than that of NiSe–Ni₃Se₂. This is because the rGO substrate accelerates the electron transfer and improves the electrical conductivity, increasing HER activity of catalyst.     

Three-dimensional ZnCo/MoS2–Co3S4/NF heterostructure supported on nickel foam as highly efficient catalyst for hydrogen evolution reaction

Exploring inexpensive and earth-abundant electrocatalysts for hydrogen evolution reactions is crucial in electrochemical sustainable chemistry field. In this work, a high-efficiency and inexpensive non-noble metal catalysts as alternatives to hydrogen evolution reaction (HER) was designed by one-step hydrothermal and two-step electrodeposition method. The as-prepared catalyst is composed of the synergistic MoS₂–Co₃S₄ layer decorated by ZnCo layered double hydroxides (ZnCo-LDH), which forms a multi-layer heterostructure (ZnCo/MoS₂–Co₃S₄/NF). The synthesized ZnCo/MoS₂–Co₃S₄/NF exhibits a small overpotential of 31 mV and a low Tafel plot of 53.13 mV dec^?1 at a current density of 10 mA cm^?2, which is close to the HER performance of the overpotential (26 mV) of Pt/C/NF. The synthesized ZnCo/MoS₂–Co₃S₄/NF also has good stability in alkaline solution. The excellent electrochemical performance of ZnCo/MoS₂–Co₃S₄/NF electrode originates from its abundant active sites and good electronic conductivity brought by the multilayer heterostructure. This work provides a simple and feasible way to design alkaline HER electrocatalysts by growing heterostructures on macroscopic substrates.     

Atmosphere plasma treatment and Co heteroatoms doping on basal plane of colloidal 2D VSe2 nanosheets for enhanced hydrogen evolution

Structural engineering of highly efficient electrocatalysts based on 2D transition metal dichalcogenides (TMDs) for hydrogen evolution reaction (HER) is of great significance for sustainable energy conversion processes. Herein, a novel basal-plane engineering of 2D colloidal VSe₂ nanosheets has been developed for highly enhanced HER performance via a synergistic combination of atmosphere plasma (AP) treatment and Co basal-plane doping. Systematic experiments and theoretical calculations show that the AP treatment not only efficiently removes the organic ligands, but also introduces defects and cracks as more active sites on the basal plane; while the Co basal-plane doping and defects further optimize Gibbs free energy of hydrogen adsorbed on the Se sites. Such AP treated 5 % Co doped VSe₂ electrocatalyst exhibits onset overpotential of only 160 mV, Tafel slope of 42 mV/decade and turnover frequency (TOF) of 6.4 S⁻¹ at 260 mV, comparable to the most active TMDs electrocatalysts. This work provides fresh insights into the utilization of “clean surface”, defects/cracks and heteroatom doping on basal plane of 2D nanosheets for catalytic application.     

Structure and electrocatalytic hydrogen evolution performance of Mo2C thin films prepared by magnetron sputtering

Mo₂C, which has a unique electronic structure similar to the electronic structure of Pt, is considered as the material with the greatest potential to replace Pt as a catalyst for the electrocatalytic hydrogen evolution reaction (HER). However, Mo₂C thin films have not attracted enough attention in the field of electrocatalysis. This work proposes a method for preparing Mo₂C thin films as a catalyst for electrocatalytic HER through radiofrequency magnetron sputtering. The HER activity of the Mo₂C thin film in acidic and alkaline media is studied by changing the deposition power of the Mo₂C target and doping Ni for structural modification. Results show that increasing the deposition power of Mo₂C can significantly enhance the HER activity of the films in acidic and alkaline media, and metal Ni doping can further enhance the HER activity of the Mo₂C films. In an alkaline environment at a current density of 10 mA cm⁻², the films demonstrate an overpotential of as low as 163 mV with a Tafel slope of 107 mV·dec⁻¹. In acidic media, the films present the corresponding overpotential of 201 mV and a Tafel slope of as low as 96 mV·dec⁻¹. Moreover, the Ni-doped Mo₂C films have excellent HER stability. The synergy between doped Ni and Mo vacancies optimizes the strength of the Mo–H bond and the adsorption and desorption equilibrium of active H, thus enhancing HER kinetics. This work guides the possible structural design of Mo₂C thin films for electrocatalytic HER.     

Facile construction of porous and heterostructured molybdenum nitride/carbide nanobelt arrays for large current hydrogen evolution reaction

The development of cost-effective, highly efficient and stable electrocatalysts for alkaline water electrolysis at a large current density has attracted considerable attention. Herein, we reported a one-dimensional (1D) porous Mo₂C/Mo₂N heterostructured electrocatalyst on carbon cloth as robust electrode for large current hydrogen evolution reaction (HER). The MoO₃ nanobelt arrays and urea were used as the metal and non-metal sources to fabricate the electrocatalyst by one-step thermal reaction. Due to the in-situ formed abundant high active interfaces and porous structure, the Mo₂C/Mo₂N electrocatalyst shows enhanced HER activity and kinetics, as exemplified by low overpotentials of 54, 73, and 96 mV at a current density of 10 mA cm^?2 and small Tafel slopes of 48, 59 and 60 mV dec^?1 in alkaline, neutral and acid media, respectively. Furthermore, the optimal Mo₂C/Mo₂N catalyst only requires a low overpotential of 290 mV to reach a large current density of 500 mA cm^?2 in alkaline media, which is superior to commercial Pt/C catalyst (368 mV) and better than those of recently reported Mo-based electrocatalysts. This work paves a facile strategy to construct highly efficient and low-cost electrocatalyst for water splitting, which could be extended to fabricate other heterostructured electrocatalyst for electrocatalysis and energy conversion.