Photo-assisted highly efficient electrocatalytic N2 fixation on nonmetal-metal dual atom catalysts through the reversable evolution of active center

Abstract

The electrocatalytic reduction naturally abundant dinitrogen (N₂) to ammonia (NH₃) offers a promising alternative to the harsh Haber–Bosch process. However, developing catalysts for high-performance electrocatalytic N₂ reduction reaction (NRR) remains a significant challenge. In this study, density functional theory (DFT) calculations were employed to investigate boron-transition metal atom pairs (B–TM) supported on graphitic carbon nitride (g-C₆N₆) as dual-atom catalysts for photo-assisted electrocatalysis of NRR. It was demonstrated that B–TM atom pair can be successfully embedded on g-C₆N₆. Among the considered B–TM@g-C₆N₆ catalysts, B–Os@g-C₆N₆ exhibits exceptional catalytic activity for NRR via a consecutive mechanism, with the lowest overpotential of 0.21 V, outperforming the efficiency of widely used noble catalysts. Notably, both B and Os atoms directly participate in N₂ activation through σ-donation and π*-backdonation mechanism. Furthermore, the adsorption of intermediates can induce the reversable evolution of the active center, accelerating the NRR. Therefore, these novel characteristics endow B–Os dual atom catalyst with excellent NRR performance. Importantly, B–Os@g-C₆N₆ also shows suitable band edges and high capability of visible-light absorption, which can assist N₂ conversion under visible-light irradiation. This work offers new insights and ideas for designing nonmetal-metal atom pair as dual atom catalyst for the photo-assisted electrocatalytic reduction of N₂ to NH₃.