Self-Supported Porous NiSe2 Nanowrinkles as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Developing low cost, highly active, and stable bifunctional electrocatalysts for overall water splitting is significant for sustainable energy systems. Herein, we report the synthesis of three-dimensional porous nickel diselenide nanowrinkles anchored on nickel foam through fabricating nickel oxalate nanosheets on nickel foam by immersion, followed by selenization under a selenium vapor atmosphere. The hybrid material exhibits superior hydrogen evolution reaction and oxygen evolution reaction performances with high activity (low overpotential), favorable kinetics, and outstanding durability in alkaline solutions. An overpotential of merely 166 mV is needed to reach 10 mA cm(-2) for hydrogen evolution reaction and 235 mV for oxygen evolution reaction. The NiOOH species formed at the NiSe2 surface serves as the catalytic sites. Moreover, the electrolyzer only needs a cell voltage of 1.64 V to deliver 10 mA cm(-2) for overall water splitting and shows excellent long-term stability (80 h at 10 mA cm(-2)). The unique porous nanowrinkle structure, improved electrical conductivity, fast charge transfer kinetics, and large electrochemical surface area are responsible for the highly active and stable electrocatalric performance toward hydrogen evolution reaction/oxygen evolution reaction.