银基复合催化剂用于二氧化碳电化学还原性能研究

Research on performance of silver-based composite catalysts for electrochemical reduction of CO_(2)

由可再生能源驱动的二氧化碳电化学还原是碳中和的有效途径,但二氧化碳电化学还原仍存在低选择性、低产率、低稳定性和过电位等问题。二氧化碳电化学还原的性能与催化剂的结构和组成密切相关,因此,设计高活性的催化剂对二氧化碳电化学的商业化应用具有重要意义。利用煅烧三聚氰胺制备的C_(3)N_(4)作为银纳米颗粒的载体合成均匀分布的Ag/C_(3)N_(4),用于提高二氧化碳电化学还原制备一氧化碳的活性。C_(3)N_(4)含有富电子氮原子,作为载体能够改性金属Ag的电子结构,从而优化复合催化剂的电催化活性;Ag纳米颗粒均匀分散在C_(3)N_(4)载体上可以提高活性面积、避免团聚,进而提高反应稳定性。研究结果表明,相比于Ag/C催化剂和纯Ag纳米催化剂,Ag/C_(3)N_(4)催化剂提高了电催化二氧化碳还原制备一氧化碳的选择性、反应速率和稳定性。在电流密度为100 mA/cm^(2)以上反应7 h后,一氧化碳法拉第效率仍维持在90%以上。

Electrochemical reduction of carbon dioxide driven by renewable energy is an effective way to achieve carbon neutrality.However,the electrochemical reduction of carbon dioxide still faces problems such as low selectivity,low yield,poor stability and overpotential.The performance of carbon dioxide electrochemical reduction is closely related to the structure and composition of the catalyst,so the design of highly active catalysts is of great significance for the commercial application of carbon dioxide electrochemistry.C_(3)N_(4) prepared through calcining melamine is used as a carrier for silver nanoparticles to synthesize Ag/C_(3)N_(4) with uniform distribution to improve the catalytic activity in carbon monoxide preparation via electrochemical reduction of carbon dioxide.C_(3)N_(4) contains electron-rich nitrogen atoms,which can be used as a support to modify the electronic structure of Ag,thereby optimizing the electrocatalytic activity of the composite catalyst.Secondly,the uniform dispersion of Ag nanoparticles on C_(3)N_(4) support can increase the active area and avoid agglomeration,thereby improving the reaction stability.Study results show that compared with Ag/C catalyst and pure Ag nano-catalyst,Ag/C_(3)N_(4) catalyst presents higher selectivity,reaction rate and stability of carbon monoxide preparation by electrocatalytic carbon dioxide reduction.After the reaction has performed for 7 hours under a current density of more than 100 mA·cm^(-2),the Faraday efficiency of carbon monoxide still maintains above 90%.