Nickel-Based Bifunctional Cocatalyst to Enhance CdS Photocatalytic Hydrogen Production

Area of Science:

• Materials Science
• Photocatalysis
• Nanotechnology

Background:

• Nanocomposites are crucial for light-capturing systems in photocatalytic water splitting.
• CdS-based materials are promising for hydrogen evolution but require enhanced efficiency and stability.

Purpose of the Study:

• To synthesize CdS nanoflowers modified with nickel-based bifunctional cocatalysts (Ni/Ni(OH)2) using an in situ photodeposition method.
• To investigate the effect of cocatalyst loading on photocatalytic hydrogen evolution efficiency.
• To elucidate the mechanism behind the enhanced performance.

Main Methods:

• In situ photodeposition for synthesizing Ni/Ni(OH)2-modified CdS nanoflowers.
• Characterization using UV-vis DRS, photoluminescence, Mott-Schottky plots, linear sweep voltammetry, and electrochemical impedance spectroscopy.
• Density Functional Theory (DFT) calculations to understand reaction mechanisms.

Main Results:

• Ni/Ni(OH)2 cocatalysts significantly enhanced the photocatalytic hydrogen evolution efficiency of CdS.
• Ni-CdS-10 exhibited the highest activity (30.51 mmol g-1 h-1), 1.8x higher than Pt-CdS and 2.6x higher than pure CdS.
• An intrinsic electric field at Ni(OH)2/CdS p-n junctions facilitated charge carrier transport and separation.
• Ni and Ni(OH)2 reduced hydrogen adsorption Gibbs free energy and overpotential, improving stability and lowering cost.

Conclusions:

• The developed Ni/Ni(OH)2-CdS nanocomposite is a highly efficient and stable photocatalyst for hydrogen production.
• The bifunctional cocatalysts effectively suppress photocorrosion of CdS.
• This study offers a cost-effective approach for producing efficient photocatalysts for water splitting.