Organic ligand-assisted synthesis of Ir0.3Cr0.7O2 solid solution oxides for efficient oxygen evolution in acidic media

Construction of strong interactions between oxides is compelling for modulating the active sites towards acidic oxygen evolution reaction (OER) electrocatalysts. Here, a solid solution oxide electrocatalyst constructed by alloying of IrO2 and CrO2 (labeled as Ir0.3Cr0.7O2) is reported with an overpotential of 255 mV at a current density of 10 mA cm−2 for OER in 0.5 M H2SO4 solution, which is much lower than that of the state-of-the-art IrO2 (357 mV). The mass activity at 1.50 V vs. RHE is 47 folds than that of IrO2, and it can maintain such OER stability for more than 200 h. Detailed analysis concludes that the organic ligands-assisted synthesis of Ir0.3Cr0.7O2 can enlarge the surface-active area and provide more active sites for water oxidation, while the leaching of Cr and its strong interaction with Ir sites resulting in the formation of high chemical state oxides of Ir with superior activity for acidic OER. It is found that the significantly increasement of oxygen vacancies content during electrochemical test together with the two points mentioned above jointly promote the water oxidation activities of Ir0.3Cr0.7O2 electrocatalyst in acidic media.