Comprehensive theoretical studies on the electrocatalytic reduction of NO to NH3 using single metallic molecular complexes as catalysts

Abstract

Single metal molecule complexes (SMMCs) have been widely used in the catalysis field. We used density functional theory (DFT) to study the potential of β-diketiminate-supported transition metal complexes (TM@β-DKC) for catalytic synthesis of NH₃ from NO. The results indicate that NO can be chemically adsorbed on most TM@β-DKCs through chemisorption. Furthermore, the NO molecule prefers to adsorb via the N-end pattern with the TM–N bond formation. The most efficient NORR pathway was selected among the two possible hydrogenation pathways. Among them, Cr@β-DKC has the lowest limiting potential of 0.03 V (vs. normal hydrogen electrode (NHE)). Through the analysis of molecular orbitals and kinetic simulation, it is found that TM@β-DKC (TM = V, Cr, Rh, and Ir) has suitable band gaps and exhibits excellent catalytic activity, which can spontaneously reduce NO to NH₃. These findings indicate that Cr@β-DKC as a novel bifunctional catalyst has significant potential for application in the NORR.