Photoelectrochemical (PEC) and Photocatalytic water splitting are beneficial way to produce hydrogen as a clean fuel using solar energy. The advantage of these means over solid-state photovoltaic cells is that powder semiconductor materials can be used as a photo-absorber. To archive efficient water splitting using them, facilitation of charge separation is indispensable to suppress the recombination of photo-excited electrons and holes. The particle transfer method has been reported as a simple method to prepare electrodes by photocatalytic particles [1] and the electrode prepared by the method is can be regarded as an assembly of metal backside contact and photocatalytic particles. Preferably, ohmic-contacts are formed at backside contact while barriers are formed at solid-liquid interfaces, resulting in formation of asymmetric built-in potential in photocatalytic particles. In the case of using n-type semiconducting material as photocatalytic particles, photo-excited holes move toward solid-liquid interfaces and oxidize water while electrons move toward backside contact and reduce water.In the present study, effects of asymmetric surface modification on photocatalytic particles are investigated numerically and experimentally. A numerical study using semiconductor device simulator revealed that asymmetric built-in potential is effective to obtain efficient solar energy conversion efficiency by matching-up with improving crystallinity of photocatalitic particles. [2] Overall water splitting was experimentally confirmed using a combination of photoelectrode prepared by particle transfer method and Pt mesh counter electrode in spite of the long absorption edge of ~600 nm. References[1] T. Minegishi, N. Nishimura, J. Kubota, K. Domen, Chem. Sci., 2013, 4, 1120.[2] T. Hisatomi, T. Minegishi, K. Domen, Bull. Chem. Soc. Jpn., 2012, 85, 647655.

Effects of asymmetric surface modification on photocatalytic particles for sunlight driven water splitting

246th National Meeting (2013)

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