Hydrophobicity Modulated Interfacial Water Distribution for Enhanced Kinetics of HER

Area of Science:

• Materials Science
• Electrochemistry
• Surface Chemistry

Background:

• Interfacial water structure critically influences hydrogen evolution reaction (HER) performance.
• The precise relationship between local water organization and HER kinetics is not fully understood.

Purpose of the Study:

• To engineer a hydrophilic-hydrophobic interface for modulating interfacial water and enhancing HER kinetics.
• To investigate the impact of controlled water organization on electrochemical reactions.

Main Methods:

• Fabrication of a Nickel-Polytetrafluoroethylene (Ni-PTFE) composite interface.
• Electrochemical measurements to assess HER performance (overpotential).
• In situ Attenuated Total Reflection Surface-Enhanced Infrared Absorption Spectroscopy (ATR-SEIRAS) to analyze water structure.
• Density Functional Theory (DFT) calculations to model interfacial water arrangement.

Main Results:

• The Ni-PTFE composite reduced HER overpotential from 36 mV to 19 mV at 10 mA·cm^-2, rivaling platinum performance.
• In situ ATR-SEIRAS showed an increase in H₂O_(above-gap) from 36.6% to 50.5% at the interface.
• DFT calculations revealed a wave-like water distribution, creating distinct water-rich and water-deficient regions.

Conclusions:

• Strategic hydrophobic modification of interfaces can effectively regulate interfacial water structure.
• Optimized water organization enhances proton transfer and water dissociation, boosting HER performance.
• This approach provides insights for designing efficient electrocatalysts by controlling the water-interface.