Preparation And Properties Of Carbon-coated Nickel/nickel Oxide Electrocatalysts

Ethanol is a typical green resource,which attracting much attentions due to the advantages of easy storage,high energy density and easy production.Therefore,the preparation of high-efficiency catalysts for ethanol oxidation is a hot issue in recent research.In this paper,two kinds of carbon-coated nickel/nickel oxide catalysts with different morphologies were prepared.The catalytic abilities of them for ethanol oxidation are systematically studied and analyzed.1.Ni/NiO-C catalyst was prepared by a method of secondary calcination and the raw materials were glucose and nickel acetate.The particles of catalyst are absolutely coated in the carbon substrate,which is carbonized by glucose at high temperatures.The contents of NiO and carbon can be adjusted by changing the oxidative temperatures.Electrochemical test results show that the performance of the catalysts enhanced with the increase of NiO crystal,and the carbon substrate also plays an important role.Among all the catalysts,Ni/NiO-C3 with the largest specific surface area(99.69 m2 g-1)shows the highest current density(134.6 mA cm-2),because of the synergistic effect between the NiO crystal and carbon.The reaction mechanism of Ni/NiO-C3 for ethanol oxidation is diffusion control at low concentration and scanning rate.The current density of Ni/NiO-C3 has a good linear relationship with ethanol concentration between 0.69?40.17 mM.With the increases of ethanol concentration and scanning rate,the reaction mechanism of Ni/NiO-C3 tends to electron transfer control.The stability of Ni/NiO-C3 is also excellent.The attenuation rate of current density after 3600 s in 0.1 M ethanol solution is 0.1%,and 11.6%after 500 cycles CV test.Besides,the NiO crystal is still exist after cycle test.2.Ni/NiO/C catalyst was prepared by a method of secondary calcination and the raw materials were sucrose and nickel chloride.The results show that the morphology of catalyst is changed with the raw materials,and the NiO crystal improves the catalytic activity of catalyst for ethanol oxidation.Ni/NiO/C-350 catalyst shows the highest current density(30.77 mA g-1)and its chronoamperometry curve is stable in 0.5 M ethanol solution,indicating that the catalytic ability and stability of Ni/NiO/C-350 for ethanol oxidation are superior.In summary,the carbon-coated Ni/NiO catalyst shows the excellent catalytic performance for ethanol,which provides a new idea for the study of ethanol oxidation.