Optimizing Acidic Oxygen Evolution Reaction via Modulation Doping in Van der Waals Layered Iridium Oxide

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen evolution reaction (OER) is vital for water splitting but limited by a slow four-electron transfer process.
• Van der Waals layered oxides offer promise for OER catalysts, but their stability in acidic media is a significant challenge.
• Doping is a strategy to enhance both activity and stability, yet it is difficult in layered oxides without structural damage.

Purpose of the Study:

• To successfully dope acid-resistant niobium (Nb) into Van der Waals layered edge-shared 1T phase iridium oxide (1T-IrO2).
• To investigate the impact of Nb doping on the catalytic activity and stability of 1T-IrO2 for acidic OER.
• To elucidate the mechanism underlying the enhanced OER performance through theoretical calculations.

Main Methods:

• Alkali-assisted thermal method for Nb doping into 1T-IrO2.
• Electrochemical characterization in 0.5 M H2SO4 to evaluate OER performance.
• Proton exchange membrane water electrolyzer testing for long-term stability assessment.
• Density functional theory (DFT) calculations to study reaction mechanisms.

Main Results:

• Nb-doped 1T-IrO2 (Nb0.05Ir0.95O2) achieved a current density of 10 mA cm−2 at an overpotential of 191 mV in 0.5 M H2SO4, outperforming undoped 1T-IrO2 by 56 mV.
• Nb0.05Ir0.95O2 demonstrated stable operation at 1.2 A cm−2 for over 50 days in a proton exchange membrane water electrolyzer.
• DFT calculations indicated that Nb doping shifted the potential-determining step from OOH deprotonation to O-OH coupling.

Conclusions:

• Nb doping is an effective strategy to simultaneously enhance the activity and stability of Van der Waals layered iridium oxides for acidic OER.
• The developed Nb0.05Ir0.95O2 catalyst shows significant potential for efficient and durable water electrolysis.
• Understanding the mechanistic shift provides insights for designing next-generation electrocatalysts.