High‐Curvature Transition‐Metal Chalcogenide Nanostructures with a Pronounced Proximity Effect Enable Fast and Selective CO2 Electroreduction

Abstract A considerable challenge in the conversion of carbon dioxide into useful fuels comes from the activation of CO 2 to CO 2 .− or other intermediates, which often requires precious‐metal catalysts, high overpotentials, and/or electrolyte additives (e.g., ionic liquids). We report a microwave heating strategy for synthesizing a transition‐metal chalcogenide nanostructure that efficiently catalyzes CO 2 electroreduction to carbon monoxide (CO). We found that the cadmium sulfide (CdS) nanoneedle arrays exhibit an unprecedented current density of 212 mA cm −2 with 95.5±4.0 % CO Faraday efficiency at −1.2 V versus a reversible hydrogen electrode (RHE; without i R correction). Experimental and computational studies show that the high‐curvature CdS nanostructured catalyst has a pronounced proximity effect which gives rise to large electric field enhancement, which can concentrate alkali‐metal cations resulting in the enhanced CO 2 electroreduction efficiency.