Single, double, and triple transition metal atoms embedded in defective V3C2O2 for nitrogen reduction reaction: A DFT study

Although numerous theoretical studies on single-atom catalysts (SACs) for an efficient electrochemical nitrogen reduction reaction (NRR) have been implemented to compare their catalytic performance. However, a rigid screening criterion excludes plenty of SACs with moderate catalytic activity. To overcome this limitation, we electronically modify the d-band structure of MXenes-based SACs to achieve higher catalytic performance. Here, multiple-transition metal atoms (TMn, TM = Cr, Mo, W, n = 1-3) embedded in defective V3C2O2 are system-atically investigated. First-principles calculations reveal that with the addition of foreign Mo and W atoms, the d -band centers of TMn@V3C2O2 are negatively shifted, and more electron-deficient sites are created. Consequently, Mo2@V3C2O2, Mo3@V3C2O2, W2@V3C2O2, and W3@V3C2O2 effectively inhibit the competitive hydrogen evo-lution reaction with favorable limiting potentials of-0.31,-0.33,-0.34, and-0.31 V, respectively. Our findings provide a new avenue of efficient atomic catalysts toward NH3 production while offering a reliable strategy for tuning the NRR performance of the MXenes-based SACs.