Structure-dependent CO 2 reduction on molybdenite (MoS 2 ) electrocatalysts.

Scanning electrochemical cell microscopy (SECCM) is employed to directly identify the structure-dependent electrochemical CO 2 reduction reaction (eCO 2 RR) activity of molybdenite (MoS 2 ) electrocatalysts in an aqueous imidazolium-based aprotic ionic liquid electrolyte. Nanoscale defects, where the edge plane (EP) is exposed, are directly targeted, revealing heightened overall activity (eCO 2 RR + the competing hydrogen evolution reaction, HER) over the relatively inactive basal plane (BP). In addition, certain types of defects ( e.g. , step edges) only exhibit heightened activity under a CO 2 atmosphere ( i.e. , compared to N 2 ), indirectly confirming higher selectivity at these surface sites. Overall, this work will guide the bottom-up design of earth-abundant electrocatalysts for use in large-scale CO 2 electrolysis.