Polyoxothiometalate-Derivatized Silicon Photocathodes for Sunlight-Driven Hydrogen Evolution Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Photocatalysis

Background:

• Developing efficient and stable photocathodes is crucial for sunlight-driven hydrogen evolution.
• Polyoxothiometalates (PTMs) offer tunable electronic and catalytic properties.

Purpose of the Study:

• To investigate the efficacy of silicon photocathodes coated with {Mo3S4}-based PTM assemblies for hydrogen evolution reaction (HER).
• To compare their performance against PTMs with organic ligands and assess stability and reaction mechanisms.

Main Methods:

• Drop-casting of {Mo3S4}-based PTM assemblies onto silicon photocathodes.
• Electrochemical characterization including onset potential and overvoltage measurements.
• X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) for material analysis.

Main Results:

• PTM-coated silicon photocathodes exhibited higher catalytic efficiency (onset potential, lower overvoltage) for HER in acidic media compared to those with organic ligands.
• Performance was less effective at neutral pH (7.3).
• The modified photocathodes demonstrated enhanced stability, operating for over 40 hours at light-limited current.

Conclusions:

• {Mo3S4}-based PTM assemblies are effective for sunlight-driven HER in acid, outperforming organic ligand-modified counterparts.
• Cathodic polarization induces beneficial material transformations, including mixed-valence species formation, enhancing photoelectrocatalysis.