1. Regulation of functional groups on graphene quantum dots directs selective CO2 to CH4 conversion.
- Author
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Zhang, Tianyu, Li, Weitao, Huang, Kai, Guo, Huazhang, Li, Zhengyuan, Fang, Yanbo, Yadav, Ram Manohar, Shanov, Vesselin, Ajayan, Pulickel M., Wang, Liang, Lian, Cheng, and Wu, Jingjie
- Subjects
QUANTUM groups ,QUANTUM dots ,FUNCTIONAL groups ,METAL catalysts ,GRAPHENE - Abstract
A catalyst system with dedicated selectivity toward a single hydrocarbon or oxygenate product is essential to enable the industrial application of electrochemical conversion of CO
2 to high-value chemicals. Cu is the only known metal catalyst that can convert CO2 to high-order hydrocarbons and oxygenates. However, the Cu-based catalysts suffer from diverse selectivity. Here, we report that the functionalized graphene quantum dots can direct CO2 to CH4 conversion with simultaneous high selectivity and production rate. The electron-donating groups facilitate the yield of CH4 from CO2 electro-reduction while electron-withdrawing groups suppress CO2 electro-reduction. The yield of CH4 on electron-donating group functionalized graphene quantum dots is positively correlated to the electron-donating ability and content of electron-donating group. The graphene quantum dots functionalized by either –OH or –NH2 functional group could achieve Faradaic efficiency of 70.0% for CH4 at −200 mA cm−2 partial current density of CH4 . The superior yield of CH4 on electron-donating group- over the electron-withdrawing group-functionalized graphene quantum dots possibly originates from the maintenance of higher charge density of potential active sites (neighboring C or N) and the interaction between the electron-donating group and key intermediates. This work provides insight into the design of active carbon catalysts at the molecular scale for the CO2 electro-reduction. Electrochemical conversion of CO2 to fuels is a promising strategy to reduce the ever-increasing CO2 emission. Here, the authors developed graphene quantum dots (GQDs) catalysts to efficiently convert CO2 to CH4 and revealed the significance of electron-donating functional groups in regulating the reactivity of GQDs. [ABSTRACT FROM AUTHOR]- Published
- 2021
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