Photocatalytic properties of the nanorods. (a) Line sweep voltammograms measured from pristine TiO2 NRs (black), Sn/TiO2-0.5% NRs (red), and Sn/TiO2-1% NRs (green). The current of the pristine TiO2 NRs in dark is plotted for comparison. (b) Photocurrent density ratios between Sn/TiO2 NRs and pristine TiO2 NRs photoanodes measured at −0.4 V versus Ag/AgCl, and the inset is optical photo of a few typical packaged samples. (c) Photoconversion efficiency of the three samples as a function of applied voltage versus Ag/AgCl. (d) Time-dependent photocurrent density of the three samples at repeated on/off cycles of illumination from the solar simulator.