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Colloidal dual-band gap cell for photocatalytic hydrogen generation
Wei Li1, Graeme O'Dowd, Thomas J Whittles
1Department of Physics and Stephenson Institute for Renewable Energy, The University of Liverpool, Chadwick Building, Peach Street, Liverpool, L69 7ZF, UK. w.li8@aston.ac.uk fjaeckel@liverpool.ac.uk.
Nanoscale
|September 30, 2015
Summary
Smaller platinum-decorated cadmium sulfide (CdS) nanocrystals enhance hydrogen generation efficiency due to quantum confinement. This enables novel colloidal dual-band gap solar cells with improved performance.
Area of Science:
- Materials Science
- Nanotechnology
- Photocatalysis
- Renewable Energy
Background:
- Hydrogen generation via photocatalysis is a key area for renewable energy.
- Quantum confinement effects in semiconductor nanocrystals influence their electronic properties.
- Platinum (Pt) decoration enhances catalytic activity in cadmium sulfide (CdS) nanocrystals.
Purpose of the Study:
- To investigate the effect of quantum confinement on the internal quantum efficiency (IQE) of hydrogen generation in Pt-decorated CdS nanocrystals.
- To explore the application of size-tuned CdS nanocrystals in a colloidal dual-band gap solar cell for enhanced hydrogen production.
- To demonstrate a proof-of-principle for colloidal tandem cells utilizing differently sized nanocrystals.
Main Methods:
- Synthesis of spherical, Pt-decorated CdS nanocrystals of varying sizes (2.8 nm and 4.6 nm diameter).
- Measurement of internal quantum efficiency (IQE) for hydrogen generation as a function of nanocrystal size.
- Fabrication and characterization of colloidal solar cells using single-sized and dual-sized CdS nanocrystals to determine external quantum efficiencies (EQE).
Main Results:
- Smaller CdS nanocrystals (2.8 nm) exhibited higher IQE (17.3%) for hydrogen generation compared to larger ones (4.6 nm, 11.4%).
- The enhanced IQE in smaller nanocrystals is attributed to a larger driving force for electron and hole transfer.
- A colloidal dual-band gap cell using both 2.8 nm and 4.6 nm CdS nanocrystals achieved a higher EQE (14.7%) than cells with only 2.8 nm particles (9.4%).
Conclusions:
- Quantum confinement in Pt-decorated CdS nanocrystals is a viable strategy to tune and enhance hydrogen generation efficiency.
- Colloidal dual-band gap solar cells utilizing size-distributed nanocrystals offer a promising pathway for improved photocatalytic performance.
- This study provides a foundational proof-of-concept for developing advanced colloidal tandem solar cell architectures for efficient hydrogen fuel production.
