Boosting alkaline hydrogen evolution of Co/Co(OH)₂ nanosheet arrays with molybdate modification

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient electrocatalysts are vital for sustainable hydrogen generation via the alkaline hydrogen evolution reaction (HER).
• Sluggish water dissociation kinetics currently limit HER efficiency in alkaline media.
• Developing cost-effective alternatives to precious metal catalysts like platinum is a key challenge.

Purpose of the Study:

• To develop novel, low-cost electrocatalysts for enhanced alkaline HER.
• To investigate the effect of molybdate ion modification on cobalt-based catalysts.
• To understand the mechanism behind improved HER performance.

Main Methods:

• Fabrication of molybdate-modified Co/Co(OH)2 nanosheet arrays (MCC NSAs) using electrodeposition and impregnation.
• Electrochemical characterization including overpotential measurements at 10 mA cm⁻².
• In-situ Raman spectroscopy and density functional theory (DFT) calculations to elucidate the catalytic mechanism.

Main Results:

• MCC NSAs achieved an overpotential of only 41 mV at 10 mA cm⁻², outperforming pristine Co/Co(OH)2 NSAs.
• The modified catalyst demonstrated performance comparable to the platinum/carbon (Pt/C) benchmark.
• Electrochemical and theoretical studies indicated accelerated water dissociation and optimized intermediate adsorption.
• The catalyst exhibited excellent durability, maintaining performance for over 250 hours at 200 mA cm⁻².

Conclusions:

• Molybdate modification effectively enhances the electrocatalytic activity and stability of Co/Co(OH)2 for alkaline HER.
• The improved performance is attributed to optimized electronic structure, enhanced water dissociation, and favorable adsorption energies.
• MCC NSAs represent a promising low-cost, high-performance alternative for sustainable hydrogen production.