Boosting the oxygen evolution electrocatalysis of high-entropy hydroxides by high-valence nickel species regulation

The addition of an extra metal source induces the transformation from crystalline α-Ni(OH)2 to an amorphous NiCoFeCrMo-based high-entropy hydroxide (HEH) and maximizes the high-valence Ni3+ content in HEH. For OER electrocatalysis, the quinary HEH possesses an overpotential of 292 mV at 10 mA cm-2, a Tafel slope of 54.31 mV dec-1 and the boosted intrinsic activity, surpassing other subsystems.