As insertion of the metallic interlayer removed the observation of the non-faradaic process, this indicates that the process itself originates at the interface between the p-Si and a-TiO2. Additional characterization methods would be required to resolve the exact mechanism; however, it remains likely that the defect band of the a-TiO2 plays a role. The defect band is not required in these devices to carry out the electrochemical reaction, however it is still an electrochemically active band of states that has been shown to transport charges across interfaces. Furthermore, alignment of the silicon VB with this defect band may also facilitate photogenerated charge transfer between these two materials.