Design And Performance Research Of Carbon-Based Catalysts Towards Carbon Dioxide Electroreduction

The development of carbon dioxide（CO₂）electroreduction technique is of great significance for carbon balance and resource utilization of CO₂.It is crucial for promoting the development of CO₂ electroreduction technique to solve the difficulty of CO₂ activation,inhibit the occurance of hydrogen evolution competition and optimize the mass transfer efficiency of the reaction system.This paper starts from the design of high-performance carbon-based catalysts,solving the thermodynamic problems in CO₂ electroreduction and promoting the efficient electroreduction CO₂ to CO via enhancing the adsorption and activation of CO₂ and optimizing the mass transfer efficiency of the whole system.Combined with the advanced in-situ characterization technology,the structure-activity relationship between the material structure and catalytic performance was explored,the adsorption and activation process of CO₂ molecules on the material surface was analyzed,and the reaction mechanism of electroreduction of CO₂ to CO was explained.The specific research contents are as follows:Using phthalocyanine（Pc）and carbon nanotube（CNT）as raw materials,the polyphthalocyanine coated carbon nanotube（PPc/CNT）composite was rapidly synthesized by microwave-heating method.The effect of microwave on the structure and properties of PPc/CNT was investigated,and it was found that the microwave enabled polymerize of Pc monomer to form PPc,and PPc was uniformly coated on the surface of CNT.The effects of the raw material ratio of PPc and CNT,and the coordination of central metal on the electrochemical performance were explored.The metal-free PPc/CNT material had the best CO₂ electroreduction performance,the carbon monoxide（CO）Faradaic efficiency of 98.7%,and run stably for more than 10 h.In situ FT-IR spectroscopy was used to explore the reaction mechanism of CO₂ electroreduction catalyzed by PPc/CNT.It was found that water molecules formed intermolecular hydrogen bonds with CO₂,which co-adsorbed on the surface of the catalyst.The presence of hydrogen bonds promoted the protonation of CO₂,and accelerated the electroreduction of CO₂ to CO.Using nickel chloride,1,10-Phenanthroline and carbon black as precursors,nickel-nitrogen-carbon（Ni-N-C）composites were prepared by grinding and mixing-assisted high-temperature carbonization technology.The effect of carbonization temperature on the structure of Ni-N-C material was investigated.It was found that the Ni-N-C had the highest proportion of Ni-N species（52.9%）,corresponding provided the best performance for the electroreduction of CO₂ to CO.In the H-type reactor,Ni-N-C can achieve the CO Faraday efficiency of 97.3%and a CO partial current density of 8.4 m A cm^-2.While in the flow reactor,the CO Faraday efficiency increased to 99.9%,and the CO partial current density canreach 136.4 m A cm^-2.In situ FT-IR was used to investigate the reaction mechanism of Ni-N-C materials for electroreduction of CO₂ to CO.The CO₂ was reduced to the product CO through the process of protonation and proton-coupled electrons.