Single Transition Metal Atoms Anchored on Defective MoS 2 Monolayers for the Electrocatalytic Reduction of Nitric Oxide into Ammonia and Hydroxylamine.

Ammonia (NH 3 ) and hydroxylamine (NH 2 OH) are important feedstocks in the chemical industry. Electrocatalytic reduction of nitric oxide (eNORR) to these chemical feedstocks is desirable for green energy conversion and waste utilization. In this work, by means of density functional theory (DFT) calculations, the eNORR activity of defective single-layer MoS 2 catalysts decorated with transition metal atoms (TM@MoS 2 ) is systematically studied. Sulfur defects innately generated during the preparation of MoS 2 monolayers are natural hosting sites for TM atoms. Out of the 27 considered TM@MoS 2 (3d to 5d period) catalysts, 19 are thermodynamically stable and experimentally feasible. Among these 19 candidates, 13 exhibit a high eNORR activity toward NH 3 , while six prefer the production of NH 2 OH. Then, their abilities to inhibit hydrogen evolution reaction (HER) and byproducts (N 2 O/N 2 ) are evaluated. Eventually, five TM@MoS 2 catalysts (TM = Ni, V, Cr, Nb, Ti) are found to be promising for affording NH 3 with very low limiting potentials ( U L = -0.18 to 0 V). Two TM@MoS 2 catalysts (TM = Ag and Pt) are screened out for generating NH 2 OH, with U L of 0 V. The adsorption of NO is a good descriptor for eNORR's activity and product selectivity. Thus, the TM@MoS 2 catalysts may open a new avenue for electrochemical NH 3 /NH 2 OH synthesis and NO removal.