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.