Wrinkle-free atomically thin CdS nanosheets for photocatalytic hydrogen evolution

Area of Science:

• Materials Science
• Nanotechnology
• Photocatalysis

Background:

• Two-dimensional (2D) nanosheets are of significant research interest.
• Atomic thickness materials offer unique properties.
• Controlling material morphology is crucial for performance.

Purpose of the Study:

• To synthesize atomically thin flat cadmium sulfide (CdS) nanosheets.
• To investigate the impact of wrinkles on CdS nanosheet properties and photocatalytic activity.
• To compare the performance of flat vs. wrinkled CdS nanosheets for hydrogen evolution.

Main Methods:

• Solvent-thermal synthesis method for producing flat CdS (F-CdS) nanosheets.
• Controlled drying process to induce irreversible wrinkles, forming wrinkled CdS (W-CdS) samples.
• Characterization of morphological and optoelectronic properties.
• Photocatalytic hydrogen evolution rate measurements under visible light.

Main Results:

• Atomically thin (0.7 nm) F-CdS nanosheets with large lateral size were successfully synthesized.
• Drying induced irreversible wrinkles in W-CdS, altering their properties.
• Wrinkles reduced light absorbance, narrowed the band gap, shifted the conduction band, and accelerated charge recombination.
• F-CdS achieved a high H2 evolution rate of 138.7 mmol g-1 h-1, significantly outperforming W-CdS (52.8 mmol g-1 h-1).

Conclusions:

• The morphology of 2D materials, specifically the presence of wrinkles, critically affects their photocatalytic performance.
• Flat CdS nanosheets are highly effective photocatalysts for hydrogen production.
• Attention to wrinkle formation is essential when designing and utilizing 2D materials for photocatalysis.