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Hot Electron Extraction in SWCNT/TiO2 for Photocatalytic H2 Evolution from Water
Masahiro Yamagami1, Tomoyuki Tajima1, Zihao Zhang2
1Graduate School of Environmental and Life Science, Okayama University, 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan.
Nanomaterials (Basel, Switzerland)
|November 11, 2022
Summary
Researchers developed single-walled carbon nanotube (SWCNT)/TiO2 hybrids for efficient hydrogen production. These hybrids utilize visible light and demonstrate a hot electron pathway, with specific SWCNT types showing higher external quantum yields for hydrogen evolution.
Area of Science:
- Materials Science
- Nanotechnology
- Photocatalysis
Background:
- Single-walled carbon nanotubes (SWCNTs) and titanium dioxide (TiO2) are promising materials for photocatalysis.
- Developing efficient methods for synthesizing SWCNT/TiO2 hybrids is crucial for enhancing photocatalytic activity.
Purpose of the Study:
- To synthesize SWCNT/TiO2 hybrids using a PAMAM dendrimer as a molecular glue.
- To investigate the hydrogen evolution reaction (HER) efficiency of these hybrids under visible light irradiation.
- To elucidate the relationship between SWCNT structure and photocatalytic performance.
Main Methods:
- Synthesis of SWCNT/TiO2 hybrids employing a 1,10-bis(decyloxy)decane-core PAMAM dendrimer.
- Photocatalytic hydrogen evolution reaction using visible light (λ > 422 nm) with a sacrificial agent (1-benzyl-1,4-dihydronicotinamide, BNAH).
- Measurement of external quantum yields (EQYs) for different SWCNT chiralities ((6,5), (7,5), (8,3)) using monochromatic light.
Main Results:
- The SWCNT/TiO2 hybrids successfully produced hydrogen via photocatalysis under visible light.
- A hydrogen evolution rate of 0.95 mmol/h·g was achieved.
- The EQYs for hydrogen production varied with SWCNT chirality, with (6,5) SWCNTs showing the highest yield (5.5%), followed by (7,5) (3.6%) and (8,3) (2.2%).
- The observed trend in EQYs indicated a dependence on the C2 energy level of SWCNTs and confirmed a hot electron extraction pathway.
Conclusions:
- PAMAM dendrimer effectively acts as a molecular glue for creating SWCNT/TiO2 hybrids.
- Visible light photocatalysis of SWCNT/TiO2 hybrids is a viable route for hydrogen production.
- The chirality of SWCNTs significantly influences photocatalytic efficiency, with specific structures favoring hot electron transfer for enhanced hydrogen evolution.
