Synthesis of iron oxide nanorods for solar water oxidation
Hematite has been extensively studied as a promising material as it is inexpensive, nontoxic, and abundant; it also has a good visible light absorption. However, there are a few limitations of hematite, such as short minority carrier diffusion length, poor carrier transport properties and slow wa...
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| Format: | Final Year Project |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://hdl.handle.net/10356/73735 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | Hematite has been extensively studied as a promising material as it is inexpensive, nontoxic,
and abundant; it also has a good visible light absorption. However, there are a few
limitations of hematite, such as short minority carrier diffusion length, poor carrier
transport properties and slow water oxidation kinetics which results in low water splitting
efficiencies in comparison to the theoretical efficiency of 15 %. The performance of
hematite could be improved through modifications to the material such as elemental
doping, nanostructuring and surface treatment by surface passivation or co-catalyst
loading.
In this project, pristine hematite films were fabricated using hydrothermal synthesis for 1
hour, followed by annealing at 550 oC for 2 hours and 750 oC in air for 20 minutes
subsequently. The films were characterized by Ultraviolet-Visible spectroscopy, X-ray
Diffraction and Field Emission Scanning Electron Microscopy to investigate the physical,
crystallographic and opto-electronic properties. Through photoelectrochemical
measurements, the best pristine sample demonstrated a photocurrent of 0.60 mA cm-2 at
1.23 V vs. RHE.
Pristine hematite films were subjected to a regrowth strategy with different hydrothermal
synthesis durations followed by annealing under the similar condition as that for pristine.
Hematite films with regrowth duration of 30 minutes had the best photocurrent
performance of 0.90 mA cm-2 at 1.23 V vs. RHE. Incident Photo-to-Current Conversion
Efficiency, Open Circuit Potential and Electrochemical Impedance Spectroscopy.
Measurements were conducted to reveal the mechanism of regrowth.
The hematite films with regrowth duration of 30 minutes were deposited with a thin layer
of Co-Pi on the surface. The Co-Pi deposited regrowth hematite films achieved 1.15 mA
cm-2 at 1.23 V vs. RHE. |
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