Electron-rich Ir nanostructure supported on mesoporous Ta2O5 for enhanced activity and stability of oxygen evolution reaction

Developing cost-effective and high-performance oxygen evolution reaction (OER) catalysts is necessary for the widespread of polymer electrolyte membrane water electrolyzers (PEMWEs). Herein, mesoporous tantalum oxide (Ta2O5) is applied as support and effectively decreased the Ir amount (0.3 mgIr cm−2) in a single cell of PEMWE. The Ir nanostructure is uniformly dispersed on the mesoporous Ta2O5, improving electrical conductivity, enhancing Ir utilization, and generating a large electrochemically active surface area. X-ray photoelectron and X-ray absorption spectroscopies are used to demonstrate the strong metal-support interaction between Ir and Ta. The charge transfer from Ta to Ir has confirmed through density functional theory, which leads to enhanced OER activity of Ir/Ta2O5 (ɳ = 0.385 V) over IrO2 (ɳ = 0.48 V). Ir/Ta2O5 presents a higher activity with an overpotential of 288 ± 3.9 mV at 10 mA cm−2 and mass activity of 876.1 ± 125.1 A gIr−1 at 1.55 VRHE, which are significantly improved than Ir Black. The excellent OER activity and stability of Ir/Ta2O5 are demonstrated by operating the single cell over 120 h. This study provided insights into the nanostructure design of the OER catalyst and the chemical interaction between Ir and Ta2O5 for achieving high Ir utilization and durability.