Boosting CO2 electroreduction to ethanol through abundant grain boundaries in In2S3 nanostructures

Electrochemical CO2 reduction powered by renewable electricities is a promising solution to the target of Carbon Neutrality. In-based catalysts are often used to convert CO2 to formate. Herein, In2S3 nanocrystals were synthesized through varying hydrothermal reaction time and unexpectedly exhibited a high ethanol faradaic efficiency (FE) of 44% at a low overpotential of just 200 mV, which was attributed to abundant grain boundaries of In2S3 with nanoparticle-nanosheet hybrid structures. Furthermore, in-situ FTIR spectra and DFT calculations indicated that the sulfur in these grain boundaries enriched *CO intermediates on the catalyst surface, thereby promoting the CO-CO coupling step and ultimately facilitating ethanol production.