TM-doping modulated p-d orbital coupling to enhance the oxygen evolution performance of NiS.

The design of an ideal catalyst for the oxygen evolution reaction (OER) is essential for electrocatalytic water-splitting. The NiS (101) facet is considered a suitable electrocatalyst owing to its good conductivity and stability, but high performance remains a challenge. Our first-principles calculations show that transition metal (TM) doping can effectively modulate p-d orbital coupling resulting from TM doping-induced charge redistribution on active site Ni atoms, thus enhancing the orbital interaction between Ni-3d and O-2p as well as between Ni-3d and O-2p . This improves the binding of the active site and oxygen-containing intermediates, thereby reducing the overpotential of the OER. Mo-doped NiS can be considered a compelling OER catalyst for its better stability and lower overpotential of 0.23 V.