| Project/Area Number |
16310085
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Nanomaterials/Nanobioscience
|
|---|
| Research Institution | The University of Electro-Communications |
|---|
Principal Investigator |
KOBAYASHI Naoki The University of Electro-Communications, Faculty of Applied Physics and Chemistry, Professor (10361825)
|
|---|
| Project Period (FY) |
2004 – 2007
|
| Project Status |
Completed (Fiscal Year 2007)
|
| Budget Amount *help |
¥14,290,000 (Direct Cost: ¥13,900,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2004: ¥10,000,000 (Direct Cost: ¥10,000,000)
|
|---|
| Keywords | water photolysis / energy resource of hydrogen / semiconductor photoelectrode / nitride semiconductors / gallium nitride / indium gallium nitride / solar energy / 量子ドット / 窒化カリウム |
|---|
| Research Abstract |
Hydrogen was evolved at a zero bias when a p-type GaN cathode in an electrolyte solution is irradiated with UV light, although both hydrogen evolution rate and photocurrent decrease during irradiation. Spontaneous hydrogen evolution indicates that the conduction band-edge of p-GaN is above the reduction potential of H+(aq). From the relationship between the volume of generated hydrogen and the amount of electrons traveling from the Pt anode to the p-GaN cathode, the reaction efficiency of electrons injected from the conduction band of the p-GaN cathode with H+(aq) in a neutral Na2SO4 electrolyte solution is larger than 70%. As a result, the overall quantum efficiency for the hydrogen generation before degradation is estimated to be 4-6% at a wavelength of 340 nm by considering the incident photon-to-current efficiency of p-GaN. We also studied the electron transport between InGaN and electrolyte solution by using cyclic voltammetry, compared with Pt, Ti02/FTO (Fluorine-doped Tin Oxide glass). The forward and reverse reactions of H2→2H+ + 2e occurred at Pt and TiO2/FTO electrodes. In contrast, in GaN and In0.12Ga0.88N electrodes, only forward reaction occured and no reserve reaction of H2→2H+ + 2e was observed. These results show that GaN and In0.12Ga0.88N have higher comduction band-edge potentials than the reduction potential of H+ (aq) in water. Moreover, we observed cathodic photocurrent with p-In0.12Ga0.88N electrode under 405nm visible light irradiation in Na2SO4 solution and H2 bubbles on electrode surface were in-situ detected by monitoring the scattered light intensity.
|
