Pt-decorated high entropy FeCoNiMnCr (Oxy) hydroxides as a bifunctional electrocatalyst towards electrochemical water splitting
The sluggish kinetics of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) necessitate high overpotentials, impeding the economic viability of electrochemical water splitting. Noble metal-based catalysts (Pt/C for HER, IrO2/RuO2 for OER) suffer from high cost and scarcity, while bifunctional catalysts that simultaneously catalyze both reactions remain rare. This study reports a Pt-decorated FeCoNiMnCr high-entropy (oxy)hydroxide (HEH) on Ni foam (NF) synthesized via a facile two-step electrodeposition at ambient temperature. The resulting Pt/FeCoNiMnCr HEH/NF exhibits a three-dimensional porous architecture composed of interconnected ultrathin nanosheets, providing a large active surface area and efficient ion/mass transport. The catalyst achieves an overpotential of 306 mV at 100 mA cm−2 for OER and 116 mV at 50 mA cm−2 for HER. When employed as both anode and cathode in a two-electrode water electrolyzer, it requires only 1.56 V to reach 20 mA cm−2 and operates stably for over 50 h. The enhanced performance is attributed to the synergistic effect of the unique ultrathin nanosheet structure and electronic coupling between Pt nanoparticles and the FeCoNiMnCr HEH matrix. This strategy offers a novel route for constructing efficient bifunctional electrocatalysts with reduced noble metal loading for practical water splitting.