The material YVO4 is known as a promising photocatalyst which can produce both oxygen and hydrogen from water by UV light irradiation. Especially, it possesses a remarkable efficiency in decomposing methanol aqueous solution to produce hydrogen in the presence of a Pt co-catalyst[1]. In this conference we focus theoretical understanding on the role of Pt co-catalyst on the adsorption properties of methanol molecules onto YVO4 photocatalyst surface in contact with aqueous methanol solution by using first principles molecular dynamics and on the related electronic properties of the inhomogeneous system. Main results of this work are as follows; (1) We have found that, during the 300 K NVT dynamics, a CH3OH molecule often can be dissociatively adsorbed to the Pt co-catalyst cluster surface and the extracted H atom from the methanol by the O atom of the approaching H2O molecule forms a hydronium H3O+ species. (2) In the case that H2 molecules are solvated in the methanol aqueous solution, H2 molecules have the net effect of inhibiting the methanol dissociation. Instead, H2O molecule can be dissociated on the Pt cluster surface. We also observed the dissociation of H2 molecule at a Pt site. Such a phenomenon seems to be related to the concentration of hydrogen molecules. (3) In the detailed investigation on the electronic properties of the inhomogeneous systems, we have cleared the role of Pt co-catalyst that it can promote the carrier separation, which would enhance the excited electron life time, and the probability to transfer excited electrons to the protons, thus leading to hydrogen generation.
Literature:
1. J. Ye, Z. Zou, M. Oshikiri, T. Shishido, 2003, Materials Science Forum, Vol. 423-5: pp. 825-829.
Oshikiri.Mitsutake@nims.go.jp
