1986 Fiscal Year Final Research Report Summary
Development of the Photoelectrolysis Cell for Energy Storage Using Silicon Electrode
| Project/Area Number |
59840010
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
物理化学一般
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| Research Institution | Osaka University |
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Principal Investigator |
TSUBOMURA Hiroshi Faculty of Engineering Science, Osaka University, 基礎工学部, 教授 (20029367)
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| Co-Investigator(Kenkyū-buntansha) |
吉村 求 三菱電機株式会社, 中央研究所, 主事
平田 郁之 三菱電機株式会社, 中央研究所, 主幹
NAKATO Yoshihiro Faculty of Engineering Science, Osaka University, 基礎工学部, 助教授 (70029502)
INOUE Yoshiro Faculty of Engineering Science, Osaka University, 基礎工学部, 助手 (30093371)
ITO Ryuzo Faculty of Engineering Science, Osaka University, 基礎工学部, 教授 (10025869)
HIRATA Ikuyuki Central Research Laboratory, Mitsubishi. Electric Corp.
YOSHIMURA Motomu Central Research Laboratory, Mitsubishi Electric Corp.
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| Project Period (FY) |
1984 – 1986
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| Keywords | Chemical conversion of solar energy / Semiconductor electrode / Photoelectrchemistry / p-n Junction / Silicon / Energy conversion efficiensy / Photoelectrochemical cell / 最適設計 |
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| Research Abstract |
The decomposition of hydrogen iodide into hydrogen and iodine by use of a photoelectrochemical cell, equipped with a metal-coated p-n junction silicon electrode and a platinum counterelectrode, has been studied for the purpose of the conversion of solar energy into chemical energy. The <P^+> -n Si photoanode was remarkably stabilized by coating with a very thin (1-nm thick) platinum, tungsten or molybdenum layer having good light trasparency. The photocurrent showed no decay for more than 5000 h and the conversion efficiency exceeded 8 %. For the case of cells in which hydrogen is evolved on the <n^+> -p Si photocathode, a very high conversion efficiency of 10.8 % was obtained by using a new-type electrode having an n-type amorphous Si/p-type crystalline Si heterojunction structure. This value is the highest so far reported as to the direct solar-to chemical conversion.
The main factors controlling the conversion efficiency of a photoelectrochemical cell are: (1) ohmic resistance, (2) absortion of light by electrolyte, and (3) nonuniformity of current density on an electrode. It has been found that subdivision of a large electrode into smaller ones makes the current density distribution uniform and the ohmic resistance small. Taking account of these effects, the optimal geometry of a module has been determined, and the method of design of photoelectrochemical cells composed of these modules has been given.
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