Chemically coupling SnO 2 quantum dots and MXene for efficient CO 2 electroreduction to formate and Zn-CO 2 battery

• Published in: Proceedings of the National Academy of Sciences - PNAS 2022-10, Vol.119 (42), p.e2207326119
• Main Authors: Han, Lili, Peng, Xianyun, Wang, Hsiao-Tsu, Ou, Pengfei, Mi, Yuying, Pao, Chih-Wen, Zhou, Jigang, Wang, Jian, Liu, Xijun, Pong, Way-Faung, Song, Jun, Lin, Zhang, Luo, Jun, Xin, Huolin L
• Format: Article
• Language: English
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2207326119

Electrochemical conversion of CO into formate is a promising strategy for mitigating the energy and environmental crisis, but simultaneously achieving high selectivity and activity of electrocatalysts remains challenging. Here, we report low-dimensional SnO quantum dots chemically coupled with ultrathin Ti C T MXene nanosheets (SnO /MXene) that boost the CO conversion. The coupling structure is well visualized and verified by high-resolution electron tomography together with nanoscale scanning transmission X-ray microscopy and ptychography imaging. The catalyst achieves a large partial current density of -57.8 mA cm and high Faradaic efficiency of 94% for formate formation. Additionally, the SnO /MXene cathode shows excellent Zn-CO battery performance, with a maximum power density of 4.28 mW cm , an open-circuit voltage of 0.83 V, and superior rechargeability of 60 h. In situ X-ray absorption spectroscopy analysis and first-principles calculations reveal that this remarkable performance is attributed to the unique and stable structure of the SnO /MXene, which can significantly reduce the reaction energy of CO hydrogenation to formate by increasing the surface coverage of adsorbed hydrogen.