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.