Theoretical Establishment and Screening of Double-Atom Catalysts Supported on Biphenylene for an Efficient Electrocatalytic Nitrogen Reduction Reaction

Electrocatalytic nitrogen reduction reaction (NRR) for ammonia synthesis has received tremendous attention for its advantages of energy conservation and environmental friendliness. However, the major challenge in implementing the NRR is synthesizing suitable catalyst materials. On the other hand, double-atom catalysts (DACs) are emerging as an ideal option for NRR because of their multiple active sites and synergetic interactions between the adjacent atoms. A two-dimensional allotrope of carbon-biphenylene (BPN) was experimentally synthesized with high stability, so by using DFT calculation and the computational hydrogen electrode model, we analyzed the nitrogen activity and reduction reaction of 28 dual-atom catalysts (DACs) composed of 3d, 4d, and 5d homonuclear transition-metal dimers anchored on biphenylene (TM2@BPN). With the help of a five-step screening technique, four homonuclear DACs were identified: Fe2@BPN, Ru2@BPN, W2@BPN, and Os2@BPN. W2@BPN and Ru2@BPN specifically have ultralow limiting potentials of – 0.29 and – 0.30 V, respectively. The difference between ΔG(N2*) – ΔG(H*) and the limiting potential (UL) of NRR and hydrogen evolution reaction (HER) were considered as the selectivity descriptors, and both metals could suppress the competing HER. The orbital projected density of states (PDOS) was calculated to provide a better understanding of N2 binding on the catalyst. The multilevel descriptors (ΔG*N and ψ) provide insights into the origin of NRR activity based on energy and basic properties. In addition, electronic property calculations revealed that NRR activity is based on d-2π* coupling, which can be understood by the ″donation and acceptance″ model. Finally, our study offers important theoretical insights into designing efficient NRR catalysts with dual active centers.