Preparation And Electrochemical Performance Of Transition Metal Nitridemetal/Nitrogen Doped Ordered Mesoporous Carbon Composites

The transition metal nitride has certain ORR activity and superb stability while transition metal loaded on N-doped carbon catalyst has high activity for oxygen reduction reaction.We can couple both transition metal nitride and metal to achieve a novel catalyst containing two catalytically active substances simultaneously,and the catalyst can be expected to replace the expensive and scarce Pt/C as ORR catalyst.In this thesis,we synthesized the transition metal nitride-metal / N-doped ordered mesoporous carbon composite as an efficient ORR catalyst via a facile in-situ evaporation-induced self-assembly strategy.Specific research results are as follows:(1)The tungsten nitride-nickle / N-doped ordered mesoporous carbon composite was prepared through an in-situ synthesis method successfully.The experimental results showed that the optimal synthetic conditions were 10% addition of tungsten source,10% addition of nickel source and 800 ? calcination under NH3(10W-10Ni-800).The 10W-10Ni-800 electrocatalyst,in which the catalytic phase was WN and Ni,possessed relatively good ORR performance in alkaline media,including high onset potential of-171 mV(VS.SCE),high limiting current density of-4.00 mA cm-2,dominant four electronic process and better stability compared with Pt/C.(2)The tungsten nitride-cobalt / N-doped ordered mesoporous carbon composite was prepared through an in-situ synthesis method successfully.The experimental results showed when the sample was calcinated at 800 ? under NH3(10W-10Co-800),it would display the best ORR performance,including high onset potential of-156 mV(VS.SCE),high limiting current density of-5.18 mA cm-2,dominant four electronic process and superbe stability compared with Pt/C.The reasons of the improved ORR performace of 10W-10Co-800 electrocatalyst,in which the catalytic phase was WN and Co,were that: The even dispersion and uniform size of electrocatalyst particles provide more reactive sites;the nitrogen doping,high specific surface area and highly ordered mesoporous channel of catalyst support(N-doped mesoporouse carbon)are conducive to the infiltration of the electrolyte;the existence of WN reinvests the catalyst with good stability and the anchored configuration of WN and Co in the N-doped mesoporouse carbon would prevent the particles from agglomerating after a long-term cycle,thereby improving the stability of the catalyst particles.(3)The Co3Mo3N-cobalt / N-doped ordered mesoporous carbon composite was prepared through an in-situ synthesis method successfully.The experimental results showed that the optimal synthetic conditions was 800 ? calcination under NH3(10W-10Ni-800).The 10Mo-10Co-800 electrocatalyst,in which the catalytic phase was Co3Mo3 N and Co,possessed relatively good ORR performance in alkaline media,including high onset potential of-157 mV(VS.SCE),high limiting current density of-4.3 mA cm-2,dominant four-electron process and better stability compared with Pt/C.