Preparation,Characterization And Electrocatalytic Properties Of Cobalt Molybdate Based Composites

Electrolytic water and fuel cell technology are indispensable for clean energy in the future.The oxygen evolution reaction(OER)is essential for anodic water electrolysis,and the oxygen reduction reaction(ORR)plays an important role in the fuel cell,so the research of catalysts with high electrocatalytic activity for OER and ORR is the key to the development of the above two technologies.Noble metal based material is most commonly used,because they can exhibit the best electrocatalytic activity.But the widely commercial application of water electrolysis and fuel cell is limited by the scarcity,high cost and the instability of precious metals.Therefore,the focus of the present study is to prepare nonprecious metal catalysts with excellent catalytic activity,which can replace noble metals.This paper mainly studies the following two aspects:1.We utilized one-pot hydrothermal method to prepare cobalt/nickel molybdate hierarchical microflowers on conductive carbon cloth(XMoO4-CC,X = Co,Ni)as three-dimensional self-supported electrodes for oxygen evolution reaction.Compared with NiMoO4-CC,CoMoO4-CC showed better catalytic activity due to its larger effective active area than that of the NiMoO4-CC catalysts.Benefiting from the synergistic effect of high surface area,enhanced mass and charge transport as well as three-dimensional conducting path,the CoMoO4-CC nanosheets electrode showed a large current density and a relatively low starting potential,delivering 10 mA cm-2 current densities at an overpotential of 290 m V and a Tafel slope of 94 mV dec-1.Furthermore,the CoMoO4-CC nanomaterial shows better electrocatalytic stability than IrO2-CC,which could be a promising electrocatalyst for large-scale water splitting.2.We also utilized one-pot hydrothermal method to prepare the CoMoO4/rGO composite of three-dimensional graphene supported cobalt molybdate.Before the hydrothermal process,ammonia solution was added to prepare nitrogen doped graphene.The combination of CoMoO4 and rGO can greatly reduce the aggregation of nanoparticles and stacking of graphene layers.The electrode material of CoMoO4/rGO showed better catalytic activity than single CoMoO4 or rGO.The composite has more positive initial potential(0.89 Vvs.RHE)and large current density.At the same time,the stability and methanol resistance of CoMoO4/rGO is better than Pt/C catalyst,which made it a potential cathode catalyst for the fuel cell.