The sub-nanometer In2O clusters on Ag nanoparticles with highly selective electrochemical CO2 reduction to formate

Abstract

Electrochemical CO2 reduction (ECR) is a potential route for establishing a carbon–neutral economy. Despite notable breakthroughs, designing a catalytic system with desired product selectivity remains a formidable challenge. Herein, we demonstrate a novel nanoarchitecture comprising sub-nanometer In2O3 clusters on Ag nanoparticles (henceforth denoted as Ag2-In8/C) for highly selective formate (HCOOH) production in ECR. As-prepared Ag2-In8/C NC with the Ag/In atomic ratio of 2/8 achieved the formate faradaic efficiency (FEHCOOH) of as high as 95.5 % at −0.9 VRHE with no obvious degradation after 7 h, surpassing the monometallic counterparts (Ag/C and In2O3/C) in selectivity and activity. The in-situ X-ray absorption spectroscopy reveals the formation of sub-nanometer In2O clusters (i.e. Indium changed its phase from In2O3 to In2O) on Ag nanoparticles under potential-driven conditions, where the high activity and selectivity of Ag2-In8/C NC originates from the robust synergistic cooperation between Ag and In2O domains at the Ag-In2O interface, underscoring its role as the active site for highly selective ECR. Moreover, an amalgamation of the physical and electrochemical analysis suggests that In2O clusters assist *OCHO formation on the surface of Ag2-In8/C NC during ECR and thus pronounced formate selectivity is achieved. In light of our findings, this study promises to unravel intricate mechanistic insights, thus paving the way for the rational design of exceptionally selective catalysts for ECR.