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

Abstract

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.