Taming Proton Transfer Through Proton Conductors to Boost Hydrogen Evolution

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The hydrogen evolution reaction (HER) is crucial for clean energy but is sensitive to interfacial pH.
• Existing methods struggle with in situ monitoring and control of pH at the electrode-electrolyte interface during HER.
• Proton consumption and hydroxide formation during HER create a significant pH gradient, limiting efficiency.

Purpose of the Study:

• To develop a novel strategy for modulating interfacial pH during HER.
• To investigate the use of nitrogen-functionalized carbon as proton-conducting mediators.
• To establish a quantitative link between nitrogen group density and interfacial proton concentration.

Main Methods:

• Incorporation of nitrogen-functionalized carbon physically mixed with platinum (Pt) catalysts.
• Electrochemical characterization using open-circuit potential transients.
• In situ infrared spectroscopy to analyze interfacial conditions.

Main Results:

• A quantitative correlation was established between nitrogen group density and interfacial proton concentration.
• Nitrogen moieties facilitated proton transport via a Grotthuss-type mechanism (proton hopping).
• The method effectively increased local proton concentration around Pt active sites during HER.

Conclusions:

• Nitrogen-functionalized carbons act as tunable proton conductors, optimizing interfacial pH for HER.
• This approach provides a generalizable platform for enhancing electrocatalytic systems sensitive to interfacial pH.
• The strategy overcomes limitations posed by hydroxide accumulation during HER operation.