A gradient Sn 4+ @Sn 2+ core@shell structure induced by a strong metal oxide-support interaction for enhanced CO 2 electroreduction.

Oxidation states of Sn in tin oxides are hard to regulate due to the uncontrollable evolution during the electrochemical CO 2 reduction reaction (CO 2 RR), thus limiting the adsorption capabilities and reaction kinetics. Herein, we propose a metal oxide-support interaction-mediated strategy to modify the electronic properties of tin oxides. A gradient Sn 4+ @Sn 2+ core@shell structure was formed as a result of electron transfer from g-C 3 N 4 to anchored SnO 2 , unlike reduced graphene oxide (rGO)-supported SnO 2 with Sn 4+ -rich surfaces. Such unique structures were revealed by the depth profiles of X-ray photoelectron spectra, and they enhanced the adsorption and stabilization of the *CO 2 ˙ - intermediate and accelerated the reaction kinetics. Consequently, SnO 2 /g-C 3 N 4 delivered a faradaic efficiency of 95.1% for the C1 products at -1.06 V, exceeding those of SnO 2 /rGO and most reported catalysts. Moreover, the performances were sustained for 70 h without obvious degradation. This work offers an alternative route to efficient catalyst design by combining oxidation state regulation and metal oxide-support interaction and contributes to the development of sustainable technologies for achieving carbon neutrality.