Engineering Coupled NiS_x -WO_2.9 Heterostructure as pH-Universal Electrocatalyst for Hydrogen Evolution Reaction.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing low-cost, highly active electrocatalysts for the hydrogen evolution reaction (HER) is crucial for efficient hydrogen fuel production.
• Achieving pH-universal electrocatalysts that perform effectively across acidic, neutral, and alkaline media remains a significant challenge.

Purpose of the Study:

• To design and synthesize a novel, pH-universal electrocatalyst for the hydrogen evolution reaction (HER).
• To investigate the structural, electronic, and catalytic properties of the developed material for hydrogen production.

Main Methods:

• Fabrication of a hierarchical heterostructure composed of nickel sulfides (NiSx) and oxygen-deficient tungsten oxide (WO2.9) on nickel foam (NF) via electrodeposition and sulfurization.
• Systematic experimental characterizations including electrochemical measurements to evaluate HER performance across a wide pH range.

Main Results:

• The NiSx-WO2.9/NF catalyst exhibited abundant active sites, fast interfacial electron transfer, and strong electronic interactions, optimizing HER kinetics.
• Achieved low overpotentials of 96 mV and 117 mV at 50 and 100 mA cm⁻² in alkaline media, surpassing many non-noble metal catalysts.
• Demonstrated impressive performance in acidic (0.5 M H2SO4) and neutral (1 M PBS) electrolytes with overpotentials of 220 mV and 304 mV at 100 mA cm⁻², respectively.

Conclusions:

• The developed NiSx-WO2.9/NF self-supporting electrode is a highly active and stable pH-universal electrocatalyst for HER.
• This work presents a novel approach for designing advanced electrocatalysts for efficient and cost-effective hydrogen production.