Single Atom Iridium Decorated Nickel Alloys Supported on Segregated MoO 2 for Alkaline Water Electrolysis.

Hetero-interface engineering has been widely employed to develop supported multicomponent catalysts for water electrolysis, but it still remains a substantial challenge for supported single atom alloys. Herein a conductive oxide MoO 2 supported Ir 1 Ni single atom alloys (Ir 1 Ni@MoO 2 SAAs) bifunctional electrocatalysts through surface segregation coupled with galvanic replacement reaction, where the Ir atoms are atomically anchored onto the surface of Ni nanoclusters via the Ir-Ni coordination accompanied with electron transfer from Ni to Ir is reported. Benefiting from the unique structure, the Ir 1 Ni@MoO 2 SAAs not only exhibit low overpotential of 48.6 mV at 10 mA cm -2 and Tafel slope of 19 mV dec -1 for hydrogen evolution reaction, but also show highly efficient alkaline water oxidation with overpotential of 280 mV at 10 mA cm -2 . Their overall water electrolysis exhibits a low cell voltage of 1.52 V at 10 mA cm -2 and excellent durability. Experiments and theoretical calculations reveal that the Ir-Ni interface effectively weakens hydrogen binding energy, and decoration of the Ir single atoms boost surface reconstruction of Ni species to enhance the coverage of intermediates (OH*) and switch the potential-determining step. It is suggested that this approach opens up a promising avenue to design efficient and durable precious metal bifunctional electrocatalysts.