2022 Fiscal Year Annual Research Report
Chemical design and DFT approach of heterojunction photocatalysts for CO2 reduction
| Project/Area Number |
21F21342
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| Allocation Type | Single-year Grants |
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| Research Institution | Kyushu University |
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Principal Investigator |
笹木 圭子 九州大学, 工学研究院, 教授 (30311525)
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| Co-Investigator(Kenkyū-buntansha) |
SHENOY SULAKSHANA 九州大学, 工学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2021-11-18 – 2024-03-31
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| Keywords | photocatalysis / graphitic carbon nitride / mixed metal oxides / heterojunction / hydrogen generation / pollutant degradation |
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| Outline of Annual Research Achievements |
A simple chemical synthesis was used to prepare mixed metal oxide namely calcium ferrite (CaFe2O4). Different amounts of CaFe2O4 were mixed with right amount of urea and calcined in a muffle furnace to make graphitic carbon nitride(g-C3N4)-CaFe2O4 heterojunction. The photodegradation of ciprofloxacin and phenol was evaluated using as-synthesized composites. Improved photocatalytic performance of composite was confirmed by electrochemical and X-ray photoelectron spectroscopy analyses. Scavenging studies and electron spin resonance spectra were used to determine active species responsible for the photodegradation process. Depending on these results, the Z-scheme charge transfer pathway is proposed and confirmed. In October 2022, this work was published in Chemical Engineering Journal. In next work, hydrothermal method was used to prepare copper cobaltite (CuCo2O4) and formed a heterojunction with g-C3N4 nanotubes. Using platinum (Pt) as a co-catalyst in as-synthesized heterojunction we evaluated its performance towards photocatalytic hydrogen evolution reaction using aqueous triethanolamine solution. Two different techniques namely photo-reduction and chemical reduction were used for reducing the Pt nanoparticles over CuCo2O4/g-C3N4 composites. The photocatalytic performance was evaluated towards H2 evolution. Mechanism for the enhanced performance in the photo-reduced Pt over the composite is evaluated based on various analytical techniques such as TEM and EXAFS. Mechanism for charge transfer is proposed. The work will soon be submitted for evaluation to reputed journal.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Due to a lack of resources, we shifted our focus from CO2 reduction to hydrogen production. For analyzing the byproducts of CO2 reduction, gas chromatography (GC) is essential. Although GC is available in our lab, carrier gas used is argon, which is more suited for hydrogen detection. We need to utilize a different carrier gas (helium) to measure the byproducts like CO, CH4 from CO2 reduction. Argon is low sensitive to these gases. However, only one carrier gas can be utilized at any given time. If you try to use two different carrier gases with a single GC, you will seriously damage the column. Since most of the other researchers in the lab are focusing on hydrogen generation, I shifted my research in that direction to facilitate parallel efforts. The next fiscal year 2023, have an exciting new collaboration with an AI company whose employees are well-versed in DFT. For our hydrogen generation experiments, we hope to acquire theoretical models from them at the very least.
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| Strategy for Future Research Activity |
In upcoming research scheme, g-C3N4 nanosheets shall be treated with nitrogen plasma at different plasma power (20, 40, 60, 80 and 100 W) to modify surface properties. Activity of plasma modified g-C3N4 nanosheets shall be evaluated for simultaneous photo-reforming of glucose into hydrogen and valuable bio-chemicals. The transformed products after photo-reforming process are determined by high-performance liquid chromatography techniques. The evolved hydrogen in the simultaneous reaction process is quantified by gas chromatography. The experimental parameters shall be optimized depending on the primary lignocellulose source, its concentration, temperature of the reaction, catalyst loading amount and so on. We have already obtained some preliminary results for these plasma-treated samples and found that the ones treated at 80 W work better than the ones that were not treated. To understand the reason behind the enhanced performance of these plasma treated samples, X-ray photoelectron spectroscopy analysis must be conducted to determine surface changes happening after the plasma treatment. Also, it is required to conduct electron spin resonance analysis to know if any vacancies are being generated due to plasma treatment. Depending on characterization techniques reason for the enhanced photocatalytic performance will be explained. In addition, after optimization of parameter conditions g-C3N4 will be combined with various other mixed metal oxides to form composites for this simultaneous photocatalytic hydrogen evolution reaction and glucose conversion reaction.
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