Figure 2: (a) Absorption spectra of a 50 μM RhB solution at intervals of 30 min due to the photocatalytic activity of the FTO-A sample. (b) Ratios of to as a function of irradiation time for all tested NW samples and using no NWs. A transition occurs at approximately the ratio of 0.2, which corresponds to 10 μM, and is indicated by a dashed line.