Pd-decorated CdS nanostructures with controlled morphologies for efficient photocatalytic hydrogen evolution by water...

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Sustainable hydrogen production is crucial for a clean energy future.
• Photocatalytic water splitting using visible light offers a promising route for hydrogen generation.
• Cadmium sulfide (CdS) is a potential semiconductor photocatalyst for this application.

Purpose of the Study:

• To synthesize CdS photocatalysts with controlled crystalline phases and morphologies.
• To investigate the impact of synthesis parameters on CdS properties and photocatalytic activity.
• To enhance CdS photocatalytic performance through palladium (Pd) impregnation.

Main Methods:

• Hydrothermal synthesis using various sulfur precursors to obtain CdS with different phases and morphologies.
• Characterization using XRD, SEM, TEM, UV-vis DRS, BET, PL spectroscopy, and CO pulse chemisorption.
• Photocatalytic water splitting experiments under visible-light irradiation to measure hydrogen evolution rates.

Main Results:

• Successfully synthesized CdS with hexagonal and cubic phases, and spherical, leaf-like, and flower-like morphologies.
• Nano-spherical CdS exhibited the highest hydrogen evolution rate (1009 µmol g⁻¹), attributed to high surface area, narrow band gap, and good light absorption.
• Pd impregnation on CdS significantly boosted hydrogen production (two-fold increase) by forming a metal-semiconductor junction, reducing recombination.
• Optimized Pd loading (1-5 wt%) and demonstrated good photocatalyst stability over 12 hours.

Conclusions:

• Crystalline phase, morphology, and surface modification are critical factors in designing efficient CdS photocatalysts.
• Nano-spherical CdS, particularly when loaded with Pd, shows excellent potential for visible-light-driven hydrogen production.
• This research provides insights into optimizing semiconductor photocatalysts for sustainable energy applications.