Suppressed Jahn-Teller Distortion in MnCo2 O4 @Ni2 P 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.