2014 Fiscal Year Research-status Report
Dye-sensitized mesoporous Ta3N5 photocatalysts for water splitting under visible light with longer wavelengths up to ~600 nm
| Project/Area Number |
26810125
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| Research Institution | Kyushu University |
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Principal Investigator |
郭 利民 九州大学, カーボンニュートラル・エネルギー国際研究所, 学術研究員 (60700143)
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| Project Period (FY) |
2014-04-01 – 2016-03-31
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| Keywords | photocatalyst / mesoporous / water splitting |
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| Outline of Annual Research Achievements |
In order to achieve the organic dye sensitized crystalline mesoporous Ta3N5 for splitting water by utilizing sunlight with the wavelengths up to 600 nm, the synthesis and optimization of crystalline mesoporous Ta3N5 was the first step and the main task during the past fiscal year. Herein, mesostructured Ta3N5 has been synthesized by nitridation of mesoporous Ta2O5 (Guo, et.al, ACS Appl. Mater. Inter. 2013, 5, 11080-6; Guo, et. al, New J. Chem., 2014, 38, 5846). Various nitridation treatments has been checked, the as-prepared mesoporous Ta3N5 samples have been characterized by X-ray powder diffraction, scanning electron microscopy, tranmission electron microscopy and so on. The pure phase of mesoporous Ta3N5 can be synthesized by adjusting the nitration temperature and time. For example,the NH3 rate is 200 cc/min, the nitridation temperature is 770 oC and the nitridation time is 7 h, the as-prepared Ta3N5 showed clear mesostructure checked by electron microscopy. The surface area is 26.9 m2/g and the pore size is 16.0 nm.
Besides the mesoporous Ta3N5 synthesis and optimization, the water reduction and oxidation of the sample under visible light (sacrificed agents were used) have also been evaluated. As expected in our proposal, the H2 generating activity is much lower than the O2 generating one. The Ta3N5 sample with the highest performance was figured out.
The different dye sensitized mesoporous Ta3N5 have been tried. Unfortunatedly, no overall water splitting phonomena have been observed. The proper dye synthesis and corresponding modification experiments are in progress.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
There are three main tasks and two challenges in the proposal. The first task is the synthesis of crystalline mesoporous Ta3N5, the second one is to figure out the Ta3N5 samples with the highest performance for water reduction and oxidation and the third one the proper dye synthesis and sensitizing the mesoporous Ta3N5 for overall water splitting. Among the three tasks, the first and third ones are the two challenges. Up to now, the first one has been conquered. The as-prepared Ta3N5 samples have clear mesoporous structure and high surface area. And the third one is in progress. In addition, the sencond task has been finished, which was confirmed by several series experiments to elvaluate the photocatalytic performance of as-prepared Ta3N5 samples. As expected, H2 generating activity was much lower than the O2 generating one. So now, the proper dye synthesis and Ta3N5 modification will be focused, which enhance the H2 generating activity. The continued optimization of dye screening, interfaces of dye, Ta3N5 and cocatalysts are the main taks in progress.
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| Strategy for Future Research Activity |
Water splitting performance evaluation under visible light radiation using as-designed dye modified mesoporous Ta3N5 and simultaneously optimization of interfaces among dye, Ta3N5 and co-catalysts. Performance of water splitting is the direct proof to demonstrate if the designed system is successful or not. Although three dyes were synthesized and tried , the overall water splitting has not been observed. Further work on the proper dye synthesis and interface optimization among dye, Ta3N5 and co-catalysts will be strengthened. Furthermore, The charge migration from Ta3N5 to dyes is essential step to achieve the second excitation. So the synthesis of the dye with high molecular weight and length will be a choice, which may be easier to itimately touch the surface of Ta3N5.
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| Causes of Carryover |
The article costs (such as some proposed equipments for performance evaluation) will be used in the coming fiscal year.
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| Expenditure Plan for Carryover Budget |
Some essential equipments for performance evaluation will be ordered. Some chemical agents for materials and dyes synthesis will be also ordered. In addition, plan to attend one domestic and one abroad conference.
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Research Products
(3 results)
