Titanium iso-propyloxide, ethyl cellulose and K2PtCl4 were purchased from Sigma-Aldrich. Acetic acid, nitric acid, sulfuric acidand ethanol were obtained from Sinopharm Chemical ReagentCo. Ltd (Shanghai, China). Fluorine-doped tin oxide (FTO) glasswith a sheet resistance of 15 sq−1was purchased from NipponSheet Glass Co. Ltd. All chemicals were used as received. Deionizedwater (18.2 M cm) was produced by a Millipore-Q purificationsystem and used throughout all experiments. Mesoporous TiO2col-loids and its screen-printing paste were prepared according to thereported procedure [30].