Unraveling the Beneficial Electrochemistry of IrO₂/MoO₃ Hybrid as a Highly Stable and Efficient Oxygen Evolution Reaction Catalyst

Abstract

Minimization of noble metal contents along with enhancement in electrochemical properties with high durability is a major challenge to be overcome for commercializing water electrolyzers and cheap energy storage devices. Sluggish kinetics of the oxygen evolution reaction (OER) within the electrolytic cell and high energy demand to form O═O bonds have attracted more responsiveness to this area. We report the OER beneficial mixed oxide composite of molybdenum and iridium oxides by a facile hydrothermal method. Adhered IrO2 nanoparticles on MoO3 large particles synergistically possessed a robust nature toward harsh acidic water electrolysis as compared to an alkaline environment. Mass specific OER activity of iridium active centers was greatly enhanced by 7-fold, twice the current density, and was attributed to electronic modulation of noble metal. Enhanced surface area and the existence of highly oxidative species in the O(1s) spectrum of IrO2 and two doublet regions in the X-ray photoelectron spectrum of molybdenum metal were found, accountable for the robust performance. Prepared composite possessing only 30% molar fraction of noble metal presented an excellent long-term stability for 40 000 s. Reduction in the Tafel slope from 57 to 77 mV dec–1 for IM-30 and IrO2 respectively was observed. The conducted research will open up new avenues for more applications of molybdenum oxides and their derivatives for water splitting.