Structure-dependent CO2 reduction on molybdenite (MoS2) electrocatalysts

Abstract

Scanning electrochemical cell microscopy (SECCM) is employed to directly identify the structure-dependent electrochemical CO₂ reduction reaction (eCO₂RR) activity of molybdenite (MoS₂) 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 (eCO₂RR + 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 CO₂ atmosphere (i.e., compared to N₂), 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 CO₂ electrolysis.