As the additional process in the Maxwell circuit is a non-faradaic charging process, two possible physical mechanisms were investigated experimentally. The first mechanism investigated was intercalation of ions into the a-TiO2 structure. Although known to occur in both c-TiO2 and a-TiO2, proton intercalation occurs over a wider voltage range for a-TiO2. Therefore, it has the potential to be detected with EIS at voltages negative of the HER onset. Furthermore, the 1 M H2SO4 electrolyte provides an ample concentration of protons at the a-TiO2 surface to be intercalated. Secondly, a charging process at the p-Si|a-TiO2 interface was investigated by insertion of a metallic interlayer, which effectively screened interactions between the two materials.