Theoretical insights into the essential role of weak interactions in the electrocatalytic reduction of nitrobenzene: Ag-anchored graphene electrode

Abstract

We used identical transition metal dimer with six coordinated nitrogen atoms to dope a monolayer graphene to construct homonuclear double-atom catalysts (DACs) and probed their catalytic efficiency for nitrobenzene reduction reaction (Ph-NO₂RR) using density functional theory. The findings predict that Ag₂N₆@G possesses significant activity and selectivity, whose potential determining step (PDS) and competitive hydrogen evolution reaction (HER) process have the Gibbs free energy changes of 0.31 and −1.49 eV, respectively. An analysis of IRI (interaction region indicator) and IGMH (independent gradient model (IGM) based on Hirshfeld partition of molecular density) indicates a pronounced van der Waals interactions between Ph-NO₂ and Ag₂N₆@G due to the benzene ring. When silver atom is introduced, the Gibbs free energy change of its PDS is reduced by 0.09 eV compared to the pure graphene as a catalyst. Through IRI, IGMH, and charge transfer analysis, it is confirmed that the van der Waals interactions between the catalyst and nitrobenzene crucially influences the activation of Ph-NO₂.