Graphene-silicon Schottky Junction Photoelectrochemical Cells for Hydrogen Generation

Graphene, a two-dimensional (2D) network of hexagonal-structured and sp2-hybridized carbon atoms has a lot of remarkable properties, such as tunable work function, high transparency, high carrier mobility and the potential to be modified with chemical dopants. These properties make graphene really promising in transparent electrode in Schottky junction solar cell. However, beside electricity of the application for solar energy, hydrogen energy has also attracted much attention recently. As a result, how to utilize graphene/silicon Schottky junction for photoelectrochemical cells (PEC) is my thesis topic. In the first part of this thesis, we successfully demonstrated graphene/silicon Schottky junction photoelectrochemical cells for hydrogen evolution reaction (HER). With the interfacial cleaner BOE treatment, the hole trap problem can be solved and hence onset potential has anodic shift. Next, we analyze the BOE treatment effect and evaluate the role of graphene in silicon Schottky junction PEC. In the second part, we utilize graphene/silicon Schottky junction to decorate the device with Pt catalysts through photo-deposition method. The final optimized device has significant anodic shift of the onset. In comparison to bare Si with the onset of -0.2 V vs. RHE, the onset potential is shifted positively by 0.4 V. In addition, the success of Pt deposition is a proof-concept of charge separation enhancement of graphene/silicon Schottky junction.