Carbon-Coordinated Single Cr Site for Efficient Electrocatalytic N2 Fixation

Electrocatalytic nitrogen reduction reaction (NRR) is a very promising method for ammonia (NH3) synthesis under ambient conditions, which can provide alternative routes to the traditional Haber-Bosch process and realize green NH3 synthesis. In this study, the electrocatalytic performance of chromium (Cr) atom anchored to graphyne (Cr@GY) is systematically investigated using density functional theory (DFT) calculations. The results show that Cr@GY is an efficient NRR electrocatalyst which can activate the inert N equivalent to N bond sufficiently. In particular, the enzymatic mechanism is considered as the most positive catalytic pathway with the limiting potential of -0.52 V. More importantly, Cr@GY can restrict a competitive hydrogen evolution reaction (HER). The electronic properties including Bader charge, the charge difference density (CDD), the partial density of states (PDOS) and the crystal orbital Hamilton population (COHP) have been analyzed in detail. In addition, the co-doping of B and N atoms in GY is beneficial to reduce the energy barrier of the potential-determining step (PDS) and promote the smooth progress of the NRR. This work can provide theoretical guidance for the experimental synthesis of the single-atom catalysts (SACs) with high activity and stability.

Automated summary

In this study, the electrocatalytic performance of chromium (Cr) atom anchored to graphyne (Cr@GY) was systematically investigated, revealing that Cr@GY is an efficient NRR electrocatalyst that can activate the inert N equivalent to N bond sufficiently and restrict a competitive hydrogen evolution reaction (HER). The electronic properties were analyzed in detail, and it was found that the co-doping of B and N atoms in GY can reduce the energy barrier of the potential-determining step (PDS) and promote the smooth progress of the NRR, providing theoretical guidance for the synthesis of single-atom catalysts (SACs) with high activity and stability.