Black phosphorus-hosted single-atom catalyst for electrocatalytic nitrogen reduction

Designing highly selective and efficient single-atom electrocatalysts is essential for ammonia production under ambient conditions. This paper describes a density functional theory study on exploring the performance trends of transition metal complexes with P-based ligands in nitrogen reduction reaction (NRR) and further develops a design principle for high-performance single-atom catalysts (SACs) of NRR. Among the explored catalysts, W@BP (0.40 eV), Ta@BP (0.47 eV), and Nb@BP (0.53 eV) are identified as remarkable candidates with low free energy change in the potential-limiting step, high stability and high electrical conductivity for NRR. It is worth noting that almost all SACs with P-based ligands exhibit high NRR selectivity, due to the fact that they adsorb *N-2 more strongly than *H. The adsorption free energy of *N2H can be considered as a descriptor for the intrinsic activity trends in NRR. Furthermore, by constructing a volcano plot of the activity against the electronic charge on metal centers, it is demonstrated that the metal center with a moderate amount of positive charge can promote the catalytic performance of NRR.