Synthesis Of Nickel-based Core-shell Electrocatalysts And Their Catalytic Property

With growing energy crisis and environmental issues,various green energy sources such as wind energy,solar energy,tidal energy,geothermal energy,and hydrogen energy has been attracting more and more attention.Among them,hydrogen energy has attracted people's attention because of its rich resources,environmental protection,renewable energy and high energy density.The production of hydrogen via electrochemical catalysis is widely resourced,as it is environmentally friendly,sustainable,renewable,and has high energy density.Moreover,hydrogen produced by electrolyzing water and electrolyzing urea has attracted much attention due to its high technical maturity,convenient operation,high degree of automation,and pollution-free strategy.However,due to the complex electron transfer process,the semi-reactive oxygen evolution reaction?OER?and urea oxidation reaction?UOR?of the anode are inherently slow.And to promote this typical electrocatalytic oxidation process,it requires additional expensive precious metal catalysts.But,the high cost and scarce storage of these precious metals is a significant obstacle to their wide usage in energy-related fields.Therefore,it is an urgent and challenging task to develop an efficient,low-cost,stable,and environmentally-friendly electrocatalyst having excellent OER and UOR performances.Nickel-based materials have the advantages of low cost and abundant reserves,and delivered good OER and UOR activities under alkaline conditions,but still the pristine Ni-based materials suffered limited catalytic performances as well as faced a certain gap from commercial applications.By considering the fact that in comparison with pristine materials,the heterostructures,especially core-shell structures,are multifunctional electrocatalysts and possess the advantage of the synergy between the core and shells to substantially boost the catalytic reactions.Benefiting from such advantages,it would be meaningful to construct a Ni-based"core-shell"structure in order to further increase their catalytic performances via synergistically promoting the electrocatalytic oxidation process.We developed two different Ni-based heterostructures,and following are the brief details:?1?The Au@NiO nanoparticles were successfully synthesized.The UOR activity was tested under alkaline conditions.The test results show that the synthesized Au@NiO nanoparticles have excellent UOR activity and stability.This is due to the synergistic effect between the core shells,in which the gold nanoparticles can induce an electron effect as a core,changing the electronic structure of the outer layer of nickel oxide,thereby increasing its electrocatalytic activity.?2?The FeOOH@Ni?OH?₂ composite nanosheet array was successfully synthesized,and its electrocatalytic performance was tested.Due to the strong electron interaction and synergy between FeOOH and Ni?OH?_2,the electrical conductivity is effectively improved,the charge transfer is promoted,and the electrocatalytic performance is enhanced.The dual function of the electrocatalyst is subsequently realized.The results show that the FeOOH@Ni?OH?₂nanosheet composite electrocatalyst has excellent OER,UOR and EOR activities and stability under alkaline conditions.