In situ synthesis of self-supported Ir/IrO2 heterostructures via Ar-H2 plasma as efficient bifunctional catalyst for overall water splitting in acidic media

Iridium oxide (IrO2) has been intensively investigated as an efficient and stable anode catalyst for the oxygen evolution reaction (OER) in water splitting system. However, the overall water splitting performance of IrO2 is rarely studied because of its strong adsorption of hydrogen intermediates during the hydrogen evolution reaction (HER) process. Herein, a facile Ar/H2 plasma reduction strategy is developed to activate the HER performance of self-supported IrO2 by constructing a novel metal/oxide heterostructure. The in-situ synthesized Ir/IrO2 com-posite possesses excellent electrical interconnection and abundant catalytic active sites. Meanwhile, dual active sites induced by the strong interface effect between metallic Ir and IrO2 could optimize the adsorption energy and reaction path for both HER and OER. The optimized Ir-IrO2/Ti@Ar-H2 exhibits remarkable activities with a small overpotential of 58 and 211 mV toward HER and OER, respectively. Besides, Ir-IrO2/Ti@Ar-H2||Ir-IrO2/ Ti@Ar-H2 electrolyzer only requires an operational voltage of 1.48 V to afford a current density of 10 mA cm-2, much lower than that of commercial Pt/C||IrO2 (1.61 V).