Study On Metal Nanocatalysts Prepared Based On Electrochemical Regulation

Hydrogen is considered as a new energy source that can replace fossil energy that can replace fossil energy because of its high heat,sufficient raw materials,clean and pollution-free advantages.Electrochemical water splitting is an effective hydrogen production technology,which can convert renewable water energy into ideal chemical hydrogen energy.Electrochemical water splitting is composed of the hydrogen evolution reaction(HER)on cathode and the oxygen evolution reaction(OER)on anode.And it is necessary to use catalysts to achieve efficient water decomposition.At present,the widely used catalysts are precious metal electrocatalysts,but their high cost and scarcity limit their use.Therefore,the development of high-efficiency,cheap,and abundant reserves of electrocatalysts is the key to achieving low-cost hydrogen production.Based on the above problems,this paper uses electrochemical regulation strategies to optimize the material structure,and designs the following highly efficient electro catalysts:(1)The removal of sulfur atoms on the basal surface of layered MoS2 by lithium ion intercalation can obtain sulfur atom vacancies on MoS2 basal plane and greatly improve the electrocatalytic performance of MoS2.The atomic vacancies generated by desulfurization are proved to be active centers for hydrogen evolution,which can not only reduce the free energy of hydrogen adsorption,but also accelerate the electron transfer on the basal plane,optimizing HER kinetics.For these reasons,the desulfurized MoS2 displays improved HER activity with lowered overpotential of 200 mV to obtain 10 mA·cm-2,and decreased Tafel slope of 65 mV·dec-1,which is much better than the original molybdenum disulfide and other optimized molybdenum disulfide based catalysts.(2)According to the Schottky heterojunction concept,a bimetal heterostructure CoMn/CoMn2O4 was designed as a bifunctional catalyst for urea oxidation and hydrogen evolution reaction in alkaline system,replacing OER with a more oxidizable urea oxidation reaction(UOR)for energy-saving hydrogen production.Based on the Schottky heterojunction structure,CoMn/CoMn2O4 will induce self-driven charge transfer at the interface,facilitating the absorption of reactant molecules and the fracture of chemical bonds.CoMn/CoMn2O4 not only exhibits an ultra-low half-reaction overpotential in alkaline solutions,but also needs only 1.51 V to reach 10 mA·cm-2 in urea assisted complete solution as a bifunctional catalyst,showing good stability.This work provides a new strategy for breaking the limitation of slow anodizing reactions(OER)in electrolytic water hydrogen production.