Designing Bifunctional Electrocatalysts Based on Complex Cobalt-Sulfo-Boride Compound for High-Current-Density...

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Alkaline water electrolysis is key for green hydrogen production.
• Developing efficient, cost-effective bifunctional electrocatalysts is crucial for enhancing reaction rates and simplifying electrode manufacturing.
• Cobalt-based materials are promising but require optimization for improved performance.

Purpose of the Study:

• To synthesize and evaluate a novel cobalt-sulfo-boride (Co-S-B) electrocatalyst for overall alkaline water electrolysis.
• To investigate the synergistic effects of sulfur and boron on cobalt for enhanced catalytic activity.
• To assess the bifunctional activity, stability, and applicability of the Co-S-B electrocatalyst in commercial electrolyzers.

Main Methods:

• Fabrication of cobalt-sulfo-boride (Co-S-B) electrocatalyst using a simple chemical reduction method.
• Characterization of the electrocatalyst's morphology, surface area, and composition using various material characterization tools.
• Electrochemical testing, including hydrogen and oxygen evolution reactions, Tafel slope analysis, electrochemical surface area, turnover frequency, charge transfer resistance, chronoamperometric stability tests, and linear sweep voltammetry.

Main Results:

• The nanocrystalline Co-S-B exhibited a porous, nanoflake-like morphology with a high surface area.
• Co-S-B demonstrated superior bifunctional activity compared to Co-B and Co-S, with lower overpotentials (144 mV for HER, 280 mV for OER at 10 mA/cm²).
• The electrocatalyst showed excellent stability over 50 hours and 10,000 cycles, and achieved 1 A/cm² at 2.06 V in an alkaline zero-gap water electrolyzer.

Conclusions:

• The synergistic effect of sulfur and boron significantly enhances the electrocatalytic activity of cobalt.
• Co-S-B is a highly active, stable, and cost-effective bifunctional electrocatalyst for alkaline water electrolysis.
• This material holds significant promise for commercial applications in green hydrogen production.