Preparation And Electrocatalytic Performances Of Porous Carbon And Carbon-based Nanocomposites

It is an effective channel to improve the activity of oxygen reduction reaction?ORR?by designing and optimizing novel porous carbon materials and carbon-based nanocomposites.In this paper,three novel ORR catalysts based on functional carbon materials and nanocomposites were prepared,and their ORR properties were investigated.The detailed research contents and conclusions are as follows:?1?A bio-based nitrogen-doped porous activated carbon material?NDACs?with high specific surface area were prepared by an improved method using urea modification and KOH activation.The advantage of this method is that it can effective pore-forming effectively and high content of nitrogen doping,and can optimize the pore structure and nitrogen distribution inside the NDACs by optimizing the calcination time and temperature,thereby improving the ORR catalytic activity of NDACs.?2?A novel metal-organic framework material?Fe₂Co-MOF?with a bimetallic coordination center was designed by simple hydrothermal reaction.Controllable synthesis of Fe₂Co-MOF morphology and size can be achieved by multi-variable control using the coordination modifier sodium acetate and changing solvent polarity.In the post-treatment step,the prepared porous coordination polymer?Fe₂Co-MOF-2?is used as a precursor,and a thin porous carbon nanorod-supported nanocomposite?CoFe₂O₄@CNR?can be obtained by simple heat treatment.The good dispersibility of the internal particles of the CoFe₂O₄@CNR nanocomposite and the ultra-thin porous carbon nanorods effectively enhance the electron transfer and ORR catalytic efficiency.?3?Cobalt oxides?Co₃O₄/Co@NC/CNT?and cobalt-sulfur compounds?CoS₂@NC?were successfully prepared by selecting ZIF-67,a metal-organic framework material rich in carbon,nitrogen and cobalt and having a sodalite?SOD?topologically stable structure.By optimizing the precursor synthesis process and the subsequent calcination process,the Co₃O₄/Co@NC/CNT surface can have more flocculated carbon nanotube structures which are favorable for electron transport,thereby effectively improving the ORR catalytic efficiency;In the preparation process of CoS₂@NC,the gas phase vulcanization method is used instead of the traditional hydrothermal method,so that the prepared CoS₂@NC has a more reasonable multi-stage pore structure distribution,and the porous network structure can solve the activity.Various problems arising from material preparation to mass transfer ability,etc.,further enhance the catalytic activity of the material.