Mo ₂ P-Supported Metal Atoms as Bifunctional Catalysts for Oxygen Evolution/Reduction Reactions

Two-dimensional transition metal phosphides and two-dimensional transition metal dichalcogenides have similar layered crystal structures, but they show a unique advantage at the electronic structure level, with the former possessing a richer density of electronic states near the Fermi energy level compared to two-dimensional transition metal dichalcogenides. This property can significantly promote the electron transfer efficiency between the reaction intermediates and the catalyst substrate, providing a key electronic structure basis for optimizing the catalytic reaction kinetics. Based on the advantages of two-dimensional transition metal phosphides, by first-principles calculations, we systematically investigated the activity of a series of transition metal atoms loaded on Mo 2 P (TM@Mo 2 P) as single-atom catalysts for OER and ORR, where TM = Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Cd, Os, Ir, Pt, and Au. By screening the stability and catalytic performance, Au@Mo 2 P exhibited OER/ORR bifunctional activity with overpotentials of η ORR = 0.48 V and η OER = 0.49 V, respectively. Meanwhile, Ag@Mo 2 P also exhibited excellent ORR performance with an overpotential of η ORR = 0.47 V. Subsequently, volcano curves established by a linear relationship of adsorption energies describe the activity trend of TM@Mo 2 P. Its catalytic origin was explained through the d-band center. Finally, through the analysis of Bader’s charge, we found that the charge on Au is almost constant during the reaction, so we believe that the Au atom acts as an electron “bridge” in the catalytic process.