Regulation of functional groups on graphene quantum dots directs selective CO2 to CH4 conversion

Developing catalysts with high selectivity for electrochemical CO2 conversion to valuable chemicals is crucial for industrial applications. While Cu is the only known metal catalyst capable of converting CO2 to higher-order hydrocarbons and oxygenates, its selectivity remains a challenge. This study demonstrates that functionalized graphene quantum dots (GQDs) can direct CO2 electroreduction to CH4 with high selectivity and production rate. Electron-donating groups (EDGs) like -OH and -NH2 enhance CH4 yield, while electron-withdrawing groups suppress CO2 reduction. GQDs functionalized with -OH or -NH2 achieve a Faradaic efficiency of 70% for CH4 at a partial current density of -200 mA cm⁻². This enhanced CH4 yield is attributed to the maintained higher charge density of active sites and the interaction between EDGs and key intermediates. This research offers insights into designing active carbon catalysts for CO2 electroreduction at the molecular level.

Tianyu Zhang, Weitao Li, Kai Huang, Huazhang Guo, Zhengyuan Li, Yanbo Fang, Ram Manohar Yadav, Vesselin Shanov, Pulickel M. Ajayan, Liang Wang, Cheng Lian, Jingjie Wu