Suppressed Jahn–Teller Distortion in MnCo2O4@Ni2P Heterostructures to Promote the Overall Water Splitting

Jahn-Teller distortion in cobalt based spinel electrocatalysts causes poor activity and stability in potentially promising catalysts for water splitting. Here, a novel strategy to resolve this problem by interface engineering is reported, in which, Jahn-Teller distortion in MnCo₂ O₄ is significantly suppressed by in situ growth Ni₂ P nanosheets onto the MnCo₂ O₄ . The significance of interface engineering in suppressing Jahn-Teller distortion of Mn³⁺ is further investigated by X-ray photoelectron spectroscopy, the resulting increased catalytic activity and the effects of suppressed distortion demonstrated by density functional theory calculations. The resulting MnCo₂ O₄ @Ni₂ P heterostructures exhibit superior electrocatalytic activity for the both oxygen evolution reaction and hydrogen evolution reaction with small overpotentials of 240 and 57 mV at 10 mA cm^-2 , respectively. Furthermore, the heterogeneous composite electrode demonstrates a superior current density of 10 mA cm^-2 at a voltage of 1.63 V with excellent durability in a water splitting cell.