Electron-rich SnO₂ promote CO₂ activation for stable electrocatalytic CO₂ reduction

Electrocatalytic CO₂ reduction reaction (CO₂RR) to formate offers a promising route for carbon neutralization, but its reactivity is largely compromised due to the competitive hydrogen evolution reaction (HER) accompanying the activation of CO₂ at high potentials. Herein, we modulated the charge density around Sn atoms by introducing La₂Sn₂O₇ into SnO₂, with the rich grain boundaries and fast electron transport of the heterostructure promoting CO₂ reduction. Combined theoretical calculations and in situ electrochemical attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) characterization revealed enhanced activation of CO₂ and adsorption of *OCHO intermediates by the constructed electron-rich SnO₂. During the CO₂RR process over 5 % La₂Sn₂O₇/SnO₂ catalyst, the Sn oxidation state can be effectively stabilized by the oxygen vacancies and amorphous phases appearing around SnO₂, with a FE of 70.7 % for HCOOH at -0.9 V vs. RHE and stable electrolysis of 39 h. This work provides an ideal approach for the development of highly stable Sn-based electrocatalysts.