KSEF RDE: Novel approach to the study of a new alloy for energy applications

Photoelectrochemical (PEC) water splitting and photocatalytic carbon dioxide rednction are the most promising approaches for utilizing solar energy to produce clean fuels. However, the current bottleneck in the practical implementation of this technology is discovering a material that will simultaneously satisfy a number of criteria required for efficient water splitting using sunlight, These include: 1. The material must have a direct band gap between 1.7 eV and 2.2 eV. 2. Its band edge positions must straddle the water oxidation and reduction reactions. 3. The alloy must show stability under photoelectrochemical conditions. A number of inorganic catalysts including a variety of metal oxides have been explored for this application with little success. One way t.o overcome this obstacle is the band gap engineering by means of Group III-V-based ternary or quaternary compounds with a composition dependent band gap. In the present proposal, we propose a study of GaP based ternary alloys for band gap engineering for the purposes of PEC water splitting using first principles theoretical methods. GaP is a promising material since it has a band gap of 2.26 eV and its band edges straddle the water oxidation and reduction reactions. However, it has an indirect band gap. Our preliminary investigations suggests the possibility of an indirect to direct band gap transition through an isovalent low concentration doping by antimony. Therefore, this work has the potential for transformational advance in PEC water splitting and to open up the field. We will use first principles methods to obtain the band gaps, band edge positions and optical properties for Ga(8bx)Pl-x alloys for various 8b concentrations and examine the structural stability under PEC conditions.