Preparation Of Co/Ni-Based Hybrid Electrode For Electrochemical Catalysis

Consumption of energy is a bottleneck restricting the development of the world.With exhausting traditional fossil fuels,the problem of energy storage and global environmental pollution seems to be more and more serious.Therefore,it is particularly urgent to develop economically efficient and sustainable green energy.Owing to its advantages of high energy conversion efficiency,clean and renewable energy and zero carbon emission,hydrogen has been regarded as a highly efficient and novel energy carrier.Electrocatalytic water splitting under alkaline condition is considered to be one of the most promising methods for industrial application.As we all known,water splitting includes two half reactions,namely,oxygen evolution reaction?OER?at the anode and hydrogen evolution reaction?HER?at the cathode.Currently,the state-of-the-art catalysts of HER and OER are still noble Pt-based material and Ru,Ir-based metal oxide,respectively.However,their high cost,rare earth reserves and unsatisfying stability limit the large-scale commercial applications.As a consequence,it is such a significant research direction for developing non-pollution,low-price and high-efficiency electrocatalysts to improve the efficiency of water splitting.Among the various materials,cobalt-based and nickel-based electrocatalysts not only own low price and abundant reservers,but display superior electrocatalytic performance toward water splitting and exhibit tremendous practical prospective.In this paper,novel cobalt-based and nickel-based micro/nano-materials electrocatalysts are prepared,and eventually a series of highly active electrocatalysts have been obtained.The main research contents and details are summarized as follows:?1?The interlaced 2D NiMoO₄/Ni?OH?₂ hybrid nanosheets are grown veryically on porous 3D nickel foam?Ni foam?via a simple hydrothermal method,and the porous nanosheets structure?Mo-Ni-NSs?is prepared by sequent thermal reduction under H₂/Ar atmosphere.The obtained Mo-Ni-NSs-3 only requires 91 mV to achieve a current density of 10 mA/cm² and owns a small Tafel slope of 62 mV/dec,besides,its activity almost lasts for 50 h without obvious decline.?2?Through a mild one-step hydrothermal method,dense and ordered nickel-molybdenum nanowire precursor is grown on the 3D porous Ni foam.Excellentlly conductive Ni-Mo-based alloys with high catalytic activity are obtained by thermal reducing the above nanowires under H₂/Ar atmosphere.Subsequently,NiMo/Ni?OH?₂ nanowires heterostructure is prepared by a simple potentiostatic deposition method and the obtained core-shell heterostructure material is applied in the field of HER.The well-designed NiMo/Ni-10 sample exhibits the prominent activity toward HER with an overpotential as low as 10 mV to deliver a current density of 10 mA/cm² and possesses a small Tafel slope of 71 mV/dec.Additionally,its excellent HER performance could be maintained at least 100 h in 1.0 M KOH.?3?The amorphous iron cobalt molybdenum carbonate hydroxide core-shell microspheres?FeCoMo/CoMo?with remarkable catalytic activity for OER are synthesized by a one-step facile solvothermal method.The fact is found that Fe appropriately tunes energy level of catalysts toward OER.That makes the energy level of valence band lie near the equilibrium potential of OER in turn,which enables OER occur at low overpotential and shows remarkable electrocatalytical performance.The as-prepared amorphous core-shell Fe_0.25-CoMoCH only requires 263 mV for OER overpotentail to deliver the current density of 10 mA/cm²,a small Tafel slope of 56mV/dec and excellent stability.