Relation between the Photocatalytic and Photoelectrocatalytic Performance for the Particulate Semiconductor-Based Photoconversion Systems with Surface Phase Junction Structure

Although the surface phase junction can efficiently boost photocatalytic (PC) reactions, its role in photoelectrocatalytic (PEC) reactions has not been well-understood yet. In this study, we investigated the effect of the surface phase junction on the PEC performance of photoelectrodes fabricated with Ga 2 O 3 and TiO 2 particles. The surface phase junctions beneficial for PC reactions show a negative effect on PEC performance, which is mainly due to the significant influence of charge transportation between semiconductor particles by the surface phase junction. Photogenerated charge separation is promoted by the surface phase junction for both PC and PEC reactions, but the much more severe interfacial recombination occurs in the PEC reaction when charge carriers migrate across semiconductor particles to reach a conducting substrate. The opposite effects of the surface phase junction on PC and PEC performance reported here indicates that the fabrication of a heterojunction or phase junction in the right structure and sequence is vital to PEC systems based on junction, which will be helpful for the development of highly efficient photoconversion systems.