Preparation And Alkaline Electrocatalytic HER Performance Of Ni-MoO₂ Nano-composite Powder

With the growing energy crisis and environmental challenges,it is increasingly important to develop sustainable renewable energy and develop efficient energy storage and conversion technologies.Hydrogen energy,as a clean energy with zero carbon emissions during the cycle,has a higher mass energy density than other traditional chemical fuels,and is considered to be an alternative energy source for fossil fuels with limited reserves in the future.Compared with hydrogen production by hydrocarbon cracking process,the electrolysis water hydrogen production technology is a clean and sustainable energy utilization technology,and is easy to be coupled with other renewable energy sources(solar energy,wind energy,etc.).It is the future sustainable energy utilization and storage A key link in the technical network framework.However,today's commercial electrolyzed water technology is still limited by the cost of hydrogen production,and the energy conversion efficiency of the electrolyzed water process is not high.In order to improve the energy conversion efficiency,a suitable catalyst must be selected to reduce the overpotential of the water splitting reaction.At present,precious metal catalysts are still the most effective catalysts for HER and OER,and the most efficient catalyst recognized in acidic HER is Pt.Therefore,in order to realize a cost-effective water electrolysis system,the development of resource-rich non-noble metal catalysts with high catalytic activity becomes crucial.In order to solve the difficulties encountered by the classic metal catalysts in the alkaline hydrogen evolution process,this study focused on the preparation and characterization of heterostructure catalysts and innovatively used high-energy ball milling to prepare Ni-MoO2 nano-composite powder with a particle size of?100 nm.In addition,Ni and MoO2 phases form a large number of heterostructure interfaces inside the nanoparticles,which provides a large number of active sites for the alkaline electrocatalytic HER process.The Ni-MoO2 heterostructure catalyst supported on carbon cloth(loading?10mg/cm2)shows similar alkaline HER performance compared to commercial Pt/C.In this study,beginning from the preparation of Ni-MoO2 nanocomposite powder,the ball mill system was further extended to nickel-rutile structure oxide systems(MnO2,CrO2,MoO2,WO2,NbO2,and SnO2),and finally obtained a series of nickel-oxidation nanocomposite powders.The nano-composite particles have proved the high versatility of the high-energy ball milling method under this system,which provides a possibility for the systematic study of nickel-oxide heterostructure catalysts.By horizontally comparing the alkaline electrocatalytic HER activity of a series of heterostructure catalysts under nickel-rutile structure oxide system,it was found that the presence of oxide species in the nickel-oxide nanoparticles obtained by ball milling has a significant effect on the HER performance of the nanoparticles in alkaline media.For example,the catalytic performance of Ni-MoO2 nanoparticles is close to commercial Pt/C,while the catalytic performance of Ni-NiMnO2 nanoparticles is not as good as the pristine micron-sized nickel powder particles.Furthermore,for Ni-MoO2,Ni-WO2,Ni-NbO2 heterostructure catalysts,as the ionic radius of the transition metal atom M4+in the rutile structure increases,the corresponding Ni-MO2(M=Mo,W,Nb)heterostructure catalysts decrease the HER catalytic activity.The experimental results in this paper confirm the universality of the high-energy ball milling method for the preparation of nickel-oxide composite nano powders,which provides an easy way for the preparation of nano-scale heterostructure catalysts.The preparation of high-throughput systemic heterostructure catalysts is the basis for a deeper understanding of the "synergistic effect" in heterostructure catalysts and to broaden the application field of heterostructure catalysts.