Electrochemical proton insertion modulates the hydrogen evolution reaction on tungsten oxides

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts for the hydrogen evolution reaction (HER) is key to sustainable hydrogen production, reducing reliance on platinum-group metals.
• Transition metal oxides and sulfides can exhibit altered properties through ion insertion, potentially influencing their catalytic performance.
• Understanding the mechanistic role of ion insertion in electrocatalysis is crucial for designing advanced materials.

Purpose of the Study:

• To investigate the influence of proton insertion on the HER activity of layered tungsten oxide hydrates (WO₃·xH₂O).
• To elucidate the relationship between the extent of proton insertion and the electrochemical performance of tungsten oxide-based electrocatalysts.

Main Methods:

• Synthesis of various tungsten oxide hydrates and an octylamine-pillared tungsten oxide (OA-WO₃).
• Electrochemical characterization using cyclic voltammetry to assess HER activity.
• Ex situ X-ray diffraction and Raman spectroscopy to analyze structural changes during electrochemical cycling.

Main Results:

• An inverse correlation was observed between the degree of proton insertion and the HER overpotential in tungsten oxides.
• Materials with minimal proton insertion exhibited high overpotentials, indicating poor HER activity.
• Structural analysis revealed changes in bulk and surface properties upon electrochemical cycling.

Conclusions:

• Proton insertion plays a critical role in enabling high HER activity in tungsten oxide hydrates.
• Hypotheses for proton insertion's role include altering electronic band structure, influencing surface adsorption energies, or direct participation in the HER mechanism.
• This study highlights the potential of materials chemistry approaches to design efficient, non-precious metal electrocatalysts for hydrogen production.