Photoelectrocatalytic degradation of methylene blue on cadmium sulfide–sensitized titanium dioxide film

Herein, cadmium sulfide–sensitized titanium dioxide (CdS/TiO₂) deposited on a fluoride-doped tin oxide electrode is proposed for achieving the photoelectrocatalytic (PEC) degradation of methylene blue (MB). Under optimum conditions (six accumulative CdS depositions, 3.0-V DC applied biased potential, and 300-W Xe arc lamp irradiation), the prepared CdS/TiO₂ films exhibited the highest PEC degradation of MB (82 ± 3%) compared with photocatalytic (70 ± 5%) or electrocatalytic (39 ± 5%) degradation. In addition, the higher current density (0.08425 mA/cm²) and the lower charge transfer resistance (78.5 Ω) of 6-CdS/TiO₂ film were observed. These were attributable to the strong visible light absorption of CdS, the high charge separation efficiency in the CdS/TiO₂ heterostructure, and the low electron–hole recombination rate from the applied biased potential. The feasibility of 6-CdS/TiO₂ film was evaluated by the MB degradation in environmental water samples, which demonstrated a high PEC activity (71 ± 3% degradation) of CdS/TiO₂ film.