Hydrothermal Sm-doped tungsten oxide vertically plate-like array photoelectrode and its enhanced photoelectrocatalytic efficiency for degradation of organic dyes

Samarium doped tungsten oxide film was synthesized by a hydrothermal method with sodium tungstate as W precursor and samarium oxide as dopant. After annealing at 450 °C for 0.5 h, the morphology and structural characterization of as-prepared films were determined with scanning electron microscopy, X-ray diffraction and high-resolution transmission electron microscope. For the pure and Sm-doped WO₃ films serving as the photoanodes, photoelectrocatalytic properties were demonstrated by degrading methyl orange and methylene blue solution, showing that Sm-doped WO₃ film has faster degrading rate than pure WO₃ film. Photoelectrochemical properties were investigated using linear sweep voltammetry, electrochemical impedance spectroscopy, Mott–Schottky and incident photon to current conversion efficiency. Sm-doped WO₃ achieves a high photocurrent of 1.50 mA cm^?2 at 1.4 V versus. Ag/AgCl, which is 1.8 times as high as that of pure WO₃ film (0.83 mA cm^?2). Moreover, photogenerated hole injection efficiency was improved by retarding the recombination at the interface of electrode/electrolyte. The results indicate the Sm₂O₃ formed by excess doping led to a better photoelectrocatalytic and photoelectrochemical activities of Sm-doped WO₃ film, suggesting that the doping of Sm is a favorable strategy to improve the performance of WO₃ film photoanode.