MoS2 nanoflowers coupled with ultrafine Ir nanoparticles for efficient acid overall water splitting reaction

Abstract

Bi-functional electrocatalysts for acid overall water splitting reactions are crucial but still challenging to the development of proton exchange membrane water electrolysis. Herein, an efficient bi-functional catalyst of Ir/MoS2 nanoflowers (Ir/MoS2 NFs) catalyst was reported for acidic water electrolysis which can be constructed by coupling three-dimensionally interconnected MoS2 NFs with ultrafine Ir nanoparticles. A more suitable adsorption ability for the H* and *OOH intermediates was revealed, where the Ir sites were proposed as the main active center and MoS2 promoted the charge relocation to electronically modify the interfacial structure. The significant interfacial charge redistribution between the MoS2 NFs and the Ir active sites synergistically induced excellent catalytic activity and stability for the water electrolysis reaction. Specifically, the catalyst required overpotentials of 270 and 35 mV to reach a kinetic current density of 10 mA cm−2 for OER and HER, respectively, loading on the glass carbon electrode, with high catalytic kinetics, stability, and catalytic efficiency. A two-electrode system constructed by Ir/MoS2 NFs drove 10 mA cm−2 at a cell voltage of 1.55 V, about 70 mV lower than that of the commercial Pt/C||IrO2 system. In addition, partial surface oxidation of Ir nanoparticles to generate high-valent Ir species was also found significant to accelerate OER. The enhanced catalytic performance was attributed to the strong metal-support interaction in the Ir/MoS2 NFs catalyst system that changed the electronic structure of Ir metal and promoted the synergistic catalytic effect between Ir and MoS2 NFs. The work presented a novel platform of Ir-catalyst for proton exchange membrane water electrolysis.