In situ dynamic re-structuring and interfacial evolution of SnS2 for high-performance electrochemical CO2 reduction to formate

The conversion of CO2 to value-added fuels and chemicals through electrochemical reduction has garnered substantial traction as an environmentally friendly approach toward a carbon-neutral society. Surface re-structuring of catalysts stands as one of the dynamic behaviors exhibited by electrocatalytic systems, exerting a significant influence on the catalysts' chemical, electronic, and physical characteristics, and thereby impacting their catalytic capabilities. Herein, we have discovered that the re-structured SnS2 nanoflowers with in situ formed Sn nanoclusters exhibit an enhanced Faradic efficiency of up to 93% with long-term stability for selective electroreduction of CO2 to formate with dynamic surface re-structuring. The in situ generated Sn nanoclusters on SnS2 nanoflowers at negative potential were found to play a vital role in facilitating over 90% CO2 electroreduction efficiency to formate. The presence of key intermediate OCHO* was proved through in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. It was also guided by first-principal calculations that the interfacial region between Sn nanoclusters and SnS2 nanosheet acts as the most favorable catalytic site for the formation of OCHO*. This work unveils the significance of surface re-structuring behaviors of electrocatalysts under in situ environment for the pathway and mechanism of CO2 electroreduction, demonstrating the promise of structure-modulated SnS2 as a candidate for formate production.