Photoelectrochemical water splitting offers a clean and sustainable route towards hydrogen production compared to traditional fossil fuel-based methods. However, the development of efficient and stable photoanodes to perform the water oxidation half-reaction is still a major limitation in making this process commercially viable. n-Type bismuth vanadate (BiVO4) has emerged as one of the most promising photoanodes for water oxidation in recent years. However, its bandgap (~2.5 eV) and its charge transport properties can be optimized to further enhance its photoelectrochemical properties. Doping studies at the V5+ and O2- sites of BiVO4 have been shown to be an effective strategy to alter its electronic band structure and/or charge transport properties but the effect of doping at the Bi3+ site is not nearly as well-understood. In this presentation, we will demonstrate the effects that doping several lanthanide series elements (La, Ce, Sm, and Yb) at the Bi3+ site in the BiVO4 lattice has on the charge transport properties and electronic band structure of BiVO4. The effects of lanthanide ion doping with La, Ce, Sm, and Yb is investigated both experimentally and through ab initio calculations. Furthermore, the combined effect of the lanthanide doping and oxygen vacancy, which is a typical defect in BiVO4, is investigated. Each of these dopants leads to a unique modification of the electronic band structure of BiVO4, which agrees well with the experimentally obtained photoelectrochemical properties of lanthanide doped BiVO4. The new understanding obtained in this study will provide useful guidelines for the composition tuning of oxide-based photoelectrodes.

Experimental and computational elucidation of lanthanide ion doping effects in bismuth vanadate photoanodes for solar water splitting

254th National Meeting (2017)

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