Journal of Organic & Inorganic Chemistry

Phase transition induced band structure engineering of BiVO4 for solar fuel production

Euroscicon Conference on Physical Chemistry and Analytical Separation Techniques
October 08-09, 2018 Amsterdam, Netherlands

Won Jun Jo, Karen K Gleason and Jae Sung Lee

Massachusetts Institute of Technology, USA Ulsan National Institute of Science and Technology, Republic of Korea Lawrence Berkeley National Laboratory, USA

Posters & Accepted Abstracts: J Org Inorg Chem

DOI: 10.21767/2472-1123-C6-018

Abstract

Cost-effective solar water splitting requires earth abundant photocatalytic materials converting photons to working electrons in a highly efficient manner. To develop such suitable photocatalysts, their atomic structure control is of primary importance since their intrinsic attributes (e.g., electronic band structure, electric properties, catalytic activity, etc.) are governed by their atomic configuration. In this regard, BiVO4’s atomic structure has been engineered via P5+ doping and In3+/Mo6+ dual doping. The significantly enhanced photo-responsive characteristics of the doping-treated BiVO4 have been systematically studied within experimental and theoretical domains. Specifically, VO4 and PO4 oxoanion exchange in monoclinic BiVO4 significantly reduces its charge-transfer resistance by increasing charge-carrier density, and thus enhances solar-to-hydrogen efficiency up to 29.3 times, as Fig. 1 shows. Notably, this brand-new oxoanion exchange technique can be applied to other various VO4-based semiconductors to improve their electronic, catalytic and photochemical properties. To upgrade the photocatalytic performance of BiVO4 further, its electronic band structure was engineered by simultaneously substituting In3+ for Bi3+ and Mo6+ for V5+, which induced partial phase transformation from pure monoclinic BiVO4 to a mixture of monoclinic and tetragonal BiVO4. This In3+/Mo6+ doped BiVO4 has a slightly larger band-gap energy (Eg ~2.5 eV) than usual ‘yellow’ monoclinic BiVO4 (Eg ~2.4 eV) and higher (more negative) conduction band edge (-0.1 VRHE at pH 7) than H+/H2 potential (0 VRHE at pH 7). Consequently, as Fig. 2 displays, the In3+/Mo6+ doped BiVO4 is able to split water into H2 and O2 under visible-light irradiation without using any sacrificial reagents (e.g. CH3OH or AgNO3). This outcome is the first example of a pure water-splitting photocatalyst responding to visible light without any noblemetal co-catalyst.

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