Theoretical investigation of single-atom catalysts anchored on pure carbon substrate for electroreduction of NO to NH3

Abstract

NO electrochemical reduction (NOER) can convert harmful NO pollutants into useful NH₃ under ambient conditions, and thus is attracting increasing interest. With density functional theory calculations, we investigated a series of single transition metal (TM) atoms (Sc to Au) located on a pure carbon substrate C₅₅₈ (TM@C₅₅₈), as a potential electrocatalyst for NOER. The C₅₅₈ substrate could stabilize the TM atom with delocalized π electrons, and activate TM atoms via charge transfer. Cu, Ag and Au doped systems are picked out with low limiting potentials for NOER and the inhibition of side reactions. The outstanding activities of Cu-, Ag- and Au@C₅₅₈ systems are related to their appropriate d band centers and the moderate adsorption intensities of intermediates. Based on the simulations, a volcano relationship between NO binding energy and predicted activity is reported. After simulating the stability of these three single-atom catalysts, Au@C₅₅₈ is finally regarded as the most promising NOER electrocatalyst with high stability. This work is expected to help with the discovery of novel NOER electrocatalysts in future experiments.