The Synthesis And Hydrogen Evolution Properties Of Non-noble Nanoporous Composite Catalysts

With the increasing energy crisis and environmental pollution,the development of an efficient and clean renewable energy has been paid more and more attention.Hydrogen is one of the most promising green energy in the future because of its abundant reserves,high value of heat combustion and no secondary pollution in the production process.The design of catalysts with low cost and high-efficiency for hydrogen evolution reaction（HER）is the key to water splitting.At present,Pt and its alloys are the most efficient catalysts for HER.However,low storage and high cost limit the use of Pt-based materials.In recent years,Ni-based transition alloys show excellent catalytic performance in HER.Compared with Pt metal,Ni has large reserves and low cost,so the development of Ni-based catalysts is of great importance to hydrogen production.In this paper,a series of nanoporous Ni-based catalysts with self-standing structure were prepared by the electrochemical dealloying method.The porous structure can provide large specific surface area and promote mass transfer and gas release process in catalytic reaction.The effect of precursor composition and dealloying parameters on the surface morphology,phase composition and crystallinity of catalysts was studied,increasing the controllability in Ni-based catalyst production.In alkaline solution,nanoporous NiO/Al₃Ni₂ catalyst exhibits remarkable HER activity with the overpotential of 66 mV at current density of 10 mAcm^-2,and it has higher current density than the commercial Pt/C catalyst under high overpotential over 105 mV.DFT calculations suggest that the interaction between Al and Ni atoms（such as orbital hybridization and stress effect）can adjust the electronic structure of Ni,optimizing the hydrogen adsorption energy on Ni surface and enhancing the kinetics of HER.In NiO/Al₃Ni₂ catalyst,the（100）surface of Al₃Ni₂ can provide active sites for HER process,while NiO can promote water splitting and prevent intermediates poisoning on Al₃Ni₂.The synergistic effect between Al₃Ni₂ and NiO phases results in a more pronounced catalytic activity for hydrogen production.In addition,the catalyst stability is important in practical hydrogen evolution.It is reported Ti can improve the corrosion resistance,electrochemical stability and mechanical property of the fabricated material.Ti-Ni/Al₃Ti catalyst mixing crystalline and amorphous structure exhibits good stability for HER in alkane solution.In Ti-Ni/Al₃Ti catalyst,Ni atoms mainly exist in surface amorphous phase which is catalytic active for HER process.Meanwhile,the Al₃Ti in bulk material can promote conductivity of the electrode,improving the electron transfer and HER process.In this study,new nanoporous composite catalysts were developed.The synergistic effect between different phases effectively promotes the kinetics of HER in alkaline condition.Combined with the advantage of self-standing structure and nanoporous morphology,the new composite catalyst is expected to be applied for HER in water-splitting application.