(513av) Tuning Ingap Band Edge Position Via Thin Stabilization Coating

Stabilization coatings have been increasingly adopted in photoelectrochemical energy conversion due to its effectiveness in providing an extended lifetime. Additionally, we observed that the adding of thin layer coating would cause some shifts for the band edge position of photo-absorber, which is crucial for the thermodynamic spontaneity of light-driven catalytic reactions. Adding a coating layer creates two interfaces: the solid/solid interface with photo-absorber, and the coating/liquid interface with electrolyte. Based on our observations, we hypothesize that the photo-absorber band edge position depends strongly on the interfacial chemical composition. It is hypothesized that continuous change of the coating composition should tune the photo-absorber effective band edge position. Currently indium gallium phosphide (InGaP) has been used as the model system to investigate how the effective band edge is shifted by coating. We characterize the effective band edge positions of the semiconductor, by systematically varying 1) Type; 2) Thickness; and 3) Composition of the coating. Through this project, we aim to not only reveal the rule of such tunability, but demonstrate the shift of onset potential as a direct proof that the employing of suitable coating can help minimize the energy loss on the interface. This new strategy could potentially open up a broad range of chemical reactions that are thermodynamically unfavorable without the coating. This tunability will ultimately allow us to control desired selectivity towards certain reactions.