Mechanism of biochar-Cu-based catalysts construction and its electrochemical CO2 reduction performance
Linhan Dong, Dongdong Feng, Yuxin Zhang, Zhaolin Wang, Yijun Zhao, Qian Du, Jianmin Gao, Shaozeng Sun
Abstract
• Biochar has a well-developed pore structure that provides a site for CO 2 reduction. • Biochar pore size and high specific surface area provide active sites for ECO 2 RR. • Urea increases the loading of biochar loaded with Cu. • The smaller the particle size of biochar-loaded Cu, the greater the reactivity. Electrochemical CO 2 reduction can convert CO 2 into high-value-added products for special forms of energy storage and efficient carbon utilization for renewable electricity. To investigate the influence of biochar-Cu-based catalysts properties on electrochemical CO 2 reduction performance, Cu is loaded onto rice husk-based biochar by impregnation method combined with pyrolysis and calcination in this study. The three synthesized biochar-Cu-based catalysts are tested for activity and electrochemical CO 2 reduction performance in Flow Cell. The results show that biochar's properties, such as its high specific surface area, rich pore structure, and adjustable pore structure, provide sufficient sites for CO 2 reduction. Urea can relatively increase the copper loading by 44 %, but it will also increase the clustering of copper. In the reduction performance test, the current density of char-Cu-700 is 2.08 times higher than that of char-Cu and 1.45 times higher than char-Cu-N at a reduction potential of -0.45 (V vs. RHE). The current density enhancement of the catalyst loaded on biochar with Cu particle size of 10 nm is about 50 % higher than that of the catalyst with a particle size of 20 nm. It indicates that the smaller the particle size of Cu at the nanoscale, the lower the average coordination of surface atoms and the greater the catalyst's reactivity. This study provides novel ideas for synthesizing biochar-Cu-based catalysts, lays part of the theoretical foundation for using biochar-Cu-based catalysts for electrochemical CO 2 reduction, and provides experimental support for optimizing the catalyst structure.