ABSTRACT
Although solar energy is one of the most abundant and important renewable energy resources, extensive energy conversion can only be achieved by large-scale collection of solar flux. A simple calculation using the solar spectrum using NREL air mass 1.5 Global (AM 1.5 G, ~1000 W m–2) predicts that a collection area of the order of 100,000 km2 is required to meet the global energy demand. This implies that the capital cost is the major issue to be assessed for solar energy conversion technology irrespective of the conversion method used. The photocatalytic overall water splitting produces a mixture of H2 and O2, requiring water as the sole reactant, and directly forms chemical energy (H2) in a single reactor. These advantages make this technology economically feasible in terms of both capital cost and scalability. However, we lack highly efficient photocatalysts made from abundant elements using a mass-production process.
To achieve water splitting, photon energy of 1.23 eV is equivalent to 1000 nm, which is thermodynamically required to drive overall water splitting. Considering unavoidable overpotential, i.e., the excess potential above the thermodynamic potential required to overcome the activation energy, it is reasonable to target developing materials that absorb light from UV wavelengths to ~600 nm (up to a band gap of ~2.0 eV). To improve further efficiency of the photocatalysis, not only the photocatalysts with suitable band positions, but also highly efficient cocatalysts are essential. Designing the semiconductor-electrolyte, metal-semiconductor, and metal-semiconductor interfaces is becoming important for achievement of overall water splitting. Detailed strategy to improve photocatalytic efficiencies is discussed.
BIOGRAPHY
Dr. Kazuhiro Takanabe received B.Eng. M.Eng. and PhD degrees in the field of chemical engineer under supervision of Prof. K. Aika in 2001, 2003 and 2006, respectively from Tokyo Institute of Technology. During his PhD, he studied at University of Twente (2002.10-2004.12), the Netherlands in the group of Profs. L. Lefferts and K. Seshan as an exchange student. After his PhD, he worked as a postdoctoral fellow at University of California at Berkeley with Prof. E. Iglesia. Then he moved to University of Tokyo as an assistant professor in the group of Prof. K. Domen. Since 2010 August, he has been appointed as an assistant professor of chemical science at King Abdullah University of Science and Technology (KAUST), KAUST Catalysis Center (KCC) directed by Prof. J.M. Basset. Further information of the Takanabe’s group can be found at http://catec.kaust.edu.sa.
RESEARCH INTERESTS
Dr. Takanabe’s research interests include development of novel nano-materials for a variety of reactions, from conventional methane conversion to photocatalytic hydrogen production, as well as understanding the reaction mechanism involved in catalytic process using kinetic/isotopic analysis, and spectroscopic/electrochemical techniques. Topics of study include 1) Photocatalytic overall water splitting to generate harnessing hydrogen using solar energy, 2) Syngas and hydrogen generation from natural gas/ heavy hydrocarbon and biomass, 3) Methane conversion (oxidative coupling of methane), C1 chemistry and biomass conversion for useful chemicals, and 4) Novel nanomaterials for energy conversion including fuel cells.