Self-Supported Polyhedral-like Co₃S₄ Nanostructures Enabling Efficient High Current Hydrogen Evolution Reaction.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient hydrogen production via water splitting requires earth-abundant, cost-effective electrocatalysts.
• Noble metal catalysts are effective but expensive, limiting widespread application.
• Developing robust, non-noble alternatives is crucial for advancing water-splitting technologies.

Purpose of the Study:

• To develop a cost-effective and durable non-noble electrocatalyst for overall water splitting.
• To investigate the potential of cobalt sulfide (Co3S4) derived from cobalt oxide (Co3O4) for enhanced electrocatalytic activity.
• To evaluate the performance of the engineered catalyst in both hydrogen evolution reaction (HER) and overall water splitting.

Main Methods:

• Fabrication of polyhedral Co3O4 on Ni foam via a hydrothermal method.
• Anion-exchange transformation of Co3O4 to conductive Co3S4 using Na2S solution.
• Electrochemical characterization of HER activity and overall water-splitting performance in 1.0 M KOH.

Main Results:

• The engineered Co3S4 electrode exhibited excellent HER activity, requiring a low overpotential (<100 mV) at 10 mA cm-2.
• Co3S4 outperformed its Co3O4 precursor and closely benchmarked with commercial Pt/C catalysts.
• The bifunctional Co3S4 electrode achieved a cell voltage of >1.76 V at 100 mA cm-2 with over 100 hours of operational stability.

Conclusions:

• Sulfur substitution in Co3O4 significantly enhances electrical conductivity and catalytic activity for HER.
• Anion-exchanged Co3S4 is a promising, cost-effective, and durable catalyst for high-performance water splitting.
• This work demonstrates a viable strategy for designing advanced electrocatalysts using earth-abundant materials.