Chemically coupling SnO <sub>2</sub> quantum dots and MXene for efficient CO <sub>2</sub> electroreduction to formate and Zn–CO <sub>2</sub> battery
Lili Han, Xianyun Peng, Hsiao‐Tsu Wang, Pengfei Ou, Yuying Mi, Chih‐Wen Pao, Jigang Zhou, Jian Wang, Xijun Liu, W. F. Pong, Jun Song, Zhang Lin, Jun Luo, Huolin L. Xin
Abstract
Electrochemical conversion of CO 2 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 2 quantum dots chemically coupled with ultrathin Ti 3 C 2 T x MXene nanosheets (SnO 2 /MXene) that boost the CO 2 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 −2 and high Faradaic efficiency of 94% for formate formation. Additionally, the SnO 2 /MXene cathode shows excellent Zn–CO 2 battery performance, with a maximum power density of 4.28 mW cm −2 , 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 2 /MXene, which can significantly reduce the reaction energy of CO 2 hydrogenation to formate by increasing the surface coverage of adsorbed hydrogen.