The research team from a joint research program of Tokyo University of Science (TUS)and the Japan Science and Technology Agency have succeeded in producing hydrogen from water through the use of gallium nitride (GaN) crystals for the first time. If commercializable, this technology is expected to lead to the development of fuel cells that run on water and can be used in a wide range of products, from automobiles to computers.
The researchers connected a GaN wafer with platinum using wire, then immersed these in water. When light is applied to the GaN wafer, current flows through the water and causes it to decompose into oxygen and hydrogen through electrolysis. The rate of conversion efficiency, which is the ratio of hydrogen energy to the light energy used, is still 0.5 %. However the researchers improved the efficiency by 1.3 times by introducing the narrower bandgap material such as InGaN. "This can be raised to more than 20%," said Kazuhiro Ohkawa, a professor in the applied physics department at the Tokyo University of Science, who played a leading role in the research. The team plans to continue work on the project to make improvements.
Recent papers published by the scientists on this research:
"Band-edge Energies and Photoelectrochemical Properties of n-Type AlxGa1-xN and InyGa1-yN alloys"
K. Fujii, M. Ono, T. Ito, Y. Iwaki, A. Hirako, K. Ohkawa
Journal of the Electrochemical Society (accepted)
"Hydrogen generation from aqueous water using n-GaN by photoassisted electrolysis"
K. Fujii, K. Ohkawa
physica status solidi (c) 3, 2270-2273 (2006).
"Bias-assisted H2 gas generation in HCl and KOH Solutions using n-type GaN photoelectrode"
K. Fujii, K. Ohkawa
Journal of the Electrochemical Society 153, A468-A471 (2006).
"Photoelectrochemical properties of InGaN for hydrogen generation from aqueous water"
K. Fujii, K. Kusakabe, K. Ohkawa
Japanese Journal of Applied Physics 44, 7433-7435 (2005).
"Photoelectrochemical properties of p-type GaN in comparison with n-type GaN"
K. Fujii, K. Ohkawa
Japanese Journal of Applied Physics, Letter 44, L909-L911 (2005).
"Hydrogen Gas Generation from Aqueous Water Splitting by N-Type GaN Photo-Electrode with Anodic Oxidation"
K. Fujii, T. Karasawa, K. Ohkawa
Japanese Journal of Applied Physics 44, L543-L545 (2005).
For more information, please contact Dr Tadanori Mizoguchi, Tokyo University of Science, Senior Adviser for International Affairs at the contact link above.
