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.