Silk fibroin-derived carbon aerogels embedded with copper nanoparticles for efficient electrocatalytic CO2-to-CO conversion

Abstract

Metal-carbon matrix catalyst has attracted a great deal of interest in electrochemical carbon dioxide reduction reaction (CO2RR) due to its excellent electrocatalytic performance. However, the design of highly active metal–carbon matrix catalyst towards CO2RR using natural biomass and cheap chemical precursors is still under challenge. Herein, a self-assembly strategy, along with CO2 gas as acidifying agent, to fabricate silk fibroin (SF) derived carbon aerogels (CA) combining trace copper nanoparticles (SF-Cu/CA) is developed. Zinc nitrate was introduced as a pore-forming agent to further optimize the pore structure of the as-prepared catalysts to form SF-Cu/CA-1. The rich mesoporous structure and unique constitute of SF-Cu/CA-1 is conducive to exposed numerous active sites, fast electron transfer rate, and the desorption of *CO intermediate, thus leading to the electrocatalytic CO2RR of SF-Cu/CA-1 catalyst with an excellent current density of 29.4 mA cm−2, Faraday efficiency of 83.06% towards carbon monoxide (CO), high the ratio value of CO/H2 (19.58), and a long-term stability over a 10-hour period. This performance is superior to that of SF-Cu/CA catalyst (13.0 mA cm−2, FECO=58.43%, CO/H2 = 2.16). This work not only offers a novel strategy using natural biomass and cheap chemicals to build metal–carbon matrix catalyst for electrocatalytic CO2-to-CO conversion, but also is expected to promote the industrial-scale implementations of CO2 electroreduction.