Tuning the Hydrogen Evolution Activity of Co₂NiO₄ via Precursor-Controlled Synthesis.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient and durable earth-abundant electrocatalysts are crucial for scalable hydrogen production via the hydrogen evolution reaction (HER).
• Current catalysts often suffer from insufficient intrinsic activity, limiting their practical application in alkaline media.

Purpose of the Study:

• To develop a precursor-controlled hydrothermal strategy for precise morphology and surface-state regulation of spinel Co2NiO4 electrocatalysts.
• To establish a clear correlation between catalyst architecture and HER performance for alkaline hydrogen production.

Main Methods:

• A hydrothermal synthesis strategy was employed, controlling precursors to engineer the morphology of spinel Co2NiO4 grown on nickel foam.
• Hexamethylenetetramine was used as a precursor to obtain ultrathin, interconnected two-dimensional nanosheet networks (CNO-HT).
• Structural (e.g., XRD) and spectroscopic (e.g., XPS) analyses were performed to characterize the catalyst's phase, composition, and oxidation states.

Main Results:

• The CNO-HT catalyst, derived from hexamethylenetetramine, exhibited an ultrathin, highly interconnected 2D nanosheet network structure.
• This morphology promoted efficient electron transport, rapid electrolyte penetration, and maximized active site exposure.
• The CNO-HT catalyst demonstrated excellent HER performance with a low overpotential of 86 mV at 10 mA cm⁻², a small Tafel slope of 103 mV dec⁻¹, and remarkable stability for 96 hours.

Conclusions:

• Precursor-regulated nanosheet engineering is a viable and scalable strategy to enhance the intrinsic catalytic potential of spinel metal oxides.
• The developed CNO-HT catalyst offers a promising non-noble alternative for efficient and durable alkaline hydrogen production.
• This work provides actionable design principles for designing next-generation electrocatalysts for sustainable hydrogen energy.