Ni-CeO₂ And Ni-S/CeO₂ Composite Electrode Material Electrodeposited Under Supergravity Field For Hydrogen Evolution Reaction

At present,due to the demand of industrial development and ascending people's consciousness of environmental protection,an urgent need for clean and renewable energy is necessary.Therefore,hydrogen energy presents.Hydrogen energy,which is a clean and renewable energy,is expected to replace fossil fuels in the energy system in the future.A variety of hydrogen production methods have been developed,water electrolysis is safe,reliable,and recyclable method to hydrogen energy.It is not dangerous to environment.However,in the process of water electrolysis,the largest barrier is relatively high cathode overpotential,which limits the development of water electrolysis.So it is the priority among priorities for the development of studies on electrode materials with low overpotential.The researches of cathodic electrode material are almost Ni based electrode materials.In this paper,Ni-CeO₂ and Ni-S/CeO₂ were prepared by the method of super gravity deposition system,and were characterized by XRD,SEM,TEM,EDS and electrochemical methods.The effects of morphologies CeO₂ on the morphology,structure and electro-chemical properties of the prepared composite electrode were investigated.Ni-S/CeO₂ composite materials were prepared by the super-gravity electrodeposition.Because the super gravity field can enhance the mass transfer process,more CeO₂ particles deposited into the coating.Electrochemical tests showed that hydrogen evolution properties of the composite coatings under super-gravity field were better than that under conventional condition.The properties of coatings prepared at the optimum concentration of adding 7 g/L CeO₂ exhibited the highest hydrogen evolution reaction exchange current density and minimum overpotential at a certain current density.The elevated electrocatalytic performance is main the high content of CeO₂,which increases the surface area and active site.And there is a synergistic reaction between CeO₂ and Ni-S alloy.Using precipitation method prepared CeO₂ nanoflakes?CeO₂Nf?,then CeO₂ regarded as composite phase,prepared Ni-CeO₂ Nf and Ni-S/CeO₂ Nf composite material.The electrochemical tests show that Ni-CeO₂ Nf in the optimal concentration of adding 1 g/L CeO₂ Nf showed the best electro-catalytic hydrogen evolution activity,maximum exchange current density and minimum over-potential of hydrogen evolution in the studied samples.Its catalytic activity is higher than that pure Ni coating,even higher thanNi-CeO₂ coatings prepared CeO₂ particles.Higher electrochemical activity can be attributed to adding CeO₂ nanoflakes,Ni particles attached to CeO₂ nanoflakes,which increases the surface area.Respect to the Ni-S/CeO₂,the optimal addition concentration of 0.7 g/L CeO₂ Nf,the composite coating showed the best electro-catalytic hydrogen evolution activity,maximum exchange current density and minimum hydrogen overpotential in the studied samples.Its catalytic activity for hydrogen evolution is higher than that Ni-S alloy,and is higher than that Ni-S/CeO₂ coating prepared CeO₂ particles.Higher electrochemical activity can be attributed to CeO₂ nanoflakes,Ni-S alloy attached to CeO₂ nanoflakes,which increase the surface area and expose more active sites.The same as CeO₂ nanoflakes,CeO₂ nanorods?CeO₂ Nr?were synthesized by precipitation,then CeO₂ nanorods were regarded as composite phase,finally prepared NiCeO₂ Nr and Ni-S/CeO₂ Nr composite material in super-gravity device.For Ni-CeO₂ Nr,the electrochemical tests showed that adding CeO₂ Nf of the best concentration of 1 g/L prepared composite coating,which was the best electro-catalytic activity of hydrogen evolution maximum exchange current density and minimum overpotential in the studied samples.Its catalytic activity is higher than that pure Ni coating,and is higher than NiCeO₂ coatings prepared by CeO₂ particles.Higher electrochemical activity may be attributed to the CeO₂ nanorods,which opened more the mass transfer channel to favor hydrogen evolution reaction.For Ni-S/CeO₂,the optimal addition concentration of 0.3 g/L CeO₂ Nr prepared composite plating,which showed the best electro-catalytic hydrogen evolution activity,maximum exchange current density and minimum hydrogen overpotential in the studied samples.Its catalytic activity of hydrogen evolution is higher than that Ni-S alloy,and is higher than that Ni-S/CeO₂ prepared CeO₂ particles.Higher electrochemical activity can be attributed to the CeO₂ nanorods,Ni-S alloy attached to CeO₂ nanorods,which increase the surface area and expose more active sites.However,it was increasing the stress of coating that CeO₂ nanorods were deposited.So coating was easily cracked.