Electrified interfacial oxygen-down water boosts efficient and durable electrolysis.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The oxygen evolution reaction (OER) is crucial for water splitting but is limited by proton-coupled electron transfers.
• Mastering interfacial proton dynamics is key to achieving high catalytic activity and long-term stability in OER.
• Current OER catalysts struggle with efficient proton transport and stability due to corrosive intermediates.

Purpose of the Study:

• To develop a novel strategy for optimizing interfacial proton dynamics in OER.
• To engineer a ruthenium dioxide (RuO2) catalyst with enhanced water adlayer orientation for improved performance.
• To investigate the impact of controlled water adlayer structure on OER kinetics and stability.

Main Methods:

• Engineered edge dislocations into RuO2 to create stress fields influencing water adlayer orientation.
• Utilized in situ infrared spectroscopy to confirm the oxygen-down water adlayer (H2O↓) structure and molecular dipole angle.
• Employed computational simulations and electrochemical measurements to analyze proton transport and catalytic activity.

Main Results:

• Successfully established an oxygen-down water adlayer (H2O↓) on RuO2, evidenced by a molecular dipole angle of ~67°.
• The H2O↓ layer formed a rigid hydrogen-bond network, accelerating proton shuttling and preventing acid accumulation.
• Reduced the oxygen formation energy barrier from 2.02 eV to 0.85 eV, leading to a RuO2 catalyst achieving 10 mA cm⁻² at 179 mV overpotential.

Conclusions:

• The engineered H2O↓ adlayer on RuO2 significantly enhances OER activity and stability by optimizing proton dynamics.
• This approach provides a new pathway for designing highly efficient and durable electrocatalysts for water splitting.
• Achieved exceptional catalytic performance (>1,000 hours stability at 10 mA cm⁻² and >720 hours at 1 A cm⁻²) demonstrating practical viability.