Atomic-scale evidence for highly selective electrocatalytic N−N coupling on metallic MoS 2

Significance Molybdenum sulfide (MoS 2 ) is the most studied two-dimensional (2D) material bar graphene. Current research on crystal-phase engineering focuses almost exclusively on the improvement of catalytic activity. However, the potential advantages of phase engineering toward regulation of selectivity control during multistep catalytic processes remain unexplored. Here, we report atomic-scale evidence on how metallic MoS 2 shows significantly higher selectivity compared to the semiconducting phase during multielectron reduction of nitrite to nitrous oxide. Namely, a reaction intermediate specific to metallic MoS 2 increases the selectivity by decoupling the proton and electron transfer steps. This has previously been shown to be a universal mechanism to enhance selectivity, and therefore, our work opens directions of the application of 2D materials toward selective electrocatalysis.