Computational screening of transition-metal atom embedding in 1T-TaS monolayer defects as efficient oxygen-reduction/evolution-reaction bifunctional catalysts.

As the global green energy and low-carbon economy undergo rapid development, the exploration and development of high-performance, cost-effective, and stable catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) have taken on increasingly critical significance. Herein, based on comprehensive density functional theory (DFT) computations, we explore the catalytic activity of metal-atom doped 1T-TaS single-atom catalysts (SACs) TM@1T-TaS for ORR and OER, where TM = V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au. It is found that Pd@1T-TaS can be an excellent bifunctional electrocatalyst with OER and ORR overpotentials (0.47 V/0.49 V) comparable to the noble metal catalysts. In view of the good catalytic activity of Pd@1T-TaS, the 4-electron process stepwise hydrogenation reaction energy barrier was further calculated with a maximum barrier of 0.44 eV. Additionally, it has been elucidated through volcano curves evolved from the scaling relation of adsorption energy that the good catalytic activity stems from the moderate adsorption of oxygenated intermediates. Finally, d-band center and crystal orbital Hamiltonian populations methods were used to explain the catalytic origin. Suitable d-band centers lead to moderate adsorption strength, further implying good catalytic performances.