TM-doping modulated p-d orbital coupling to enhance the oxygen evolution performance of Ni₃S₂

The design of an ideal catalyst for the oxygen evolution reaction (OER) is essential for electrocatalytic water-splitting. The Ni₃S₂ (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 _xz and O-2p _y as well as between Ni-3d _z2 and O-2p _x . This improves the binding of the active site and oxygen-containing intermediates, thereby reducing the overpotential of the OER. Mo-doped Ni₃S₂ can be considered a compelling OER catalyst for its better stability and lower overpotential of 0.23 V.