Elevating the p-band centre of SnO2 nanosheets through W incorporation for promoted CO2 electroreduction

SnO2 is one of the most promising catalysts for CO2 electroreduction. However, the intrinsic low electrical conductivity and weak CO2 adsorption and activation capability have rendered the reaction kinetically sluggish and inefficient.To surmount these hurdles, herein, W was incorporated into SnO2 nanosheets to modulate the electronic structures. Compared with the pristine SnO2, the p-band centre of W-doped SnO2 was elevated towards the Fermi level, accompanied by the reduction in the band gap and work function. As a result, both the CO2 adsorption and the electron transfer process were promoted, thus lowering the activation energy barrier for CO2 reduction. Benefitting from these, a maximum faradaic efficiency of 87.8% was achieved for HCOOH at -0.9 V vs. RHE. Meanwhile, the current density and energy efficiency approached 20.92 mA cm-2 and 60%, respectively. Such performances could sustain for 14 h without obvious fading and exceeded pristine SnO2 and most reported Sn-based catalysts. Tafel slope and reaction order analyses further suggested that the reaction proceeded following a stepwise electron-proton transfer pathway with the formation of CO2·- as the rate determining step. This work demonstarted the effectiveness of electronic structure tuning in promoting the catalytic performances of p-block metal oxides and contributed to the development of efficient catalysts for sustainable energy conversion and carbon neutrality.