Photoelectrocatalytic degradation of methylene blue using F doped TiO2 photoelectrode under visible light irradiation

- A novel and low cost strategy has been developed to prepare F doped TiO2 photoelectrodes.
- The F doped TiO2 photoelectrodes exhibit a high PEC performance for the degradation of MB under visible light irradiation.
- The PEC degradation mechanism of MB was investigated by the addition of scavengers.

Photoelectrocatalysis (PEC) has attracted great interest due to cost effectiveness and high efficiency in water treatment. In this study, F doped TiO2 (F-TiO2) photoelectrodes with honeycomb like morphology were prepared, and the PEC performance was investigated. F-TiO2 particles that showed enhanced absorption of visible light were synthesized via a sol-gel method. F-TiO2 particles were anchored onto the surface of F-doped SnO2 glass by a screen-printing method to prepare the F-TiO2 photoelectrodes. The PEC performance of the F-TiO2 photoelectrodes was investigated via the degradation of methylene blue (MB) under visible light irradiation. The results show that the F-TiO2 photoelectrodes exhibited an excellent PEC performance that was affected by the F doping content, applied bias and solution pH. A maximum decolorization percentage of 97.8% was achieved by the FT-15 photoelectrode, with a 1.4 V bias at pH 9.94 after 4.0 h of visible light irradiation. The high PEC performance of the F-TiO2 photoelectrodes is mainly ascribed to the efficient separation of electron-hole (e−-h+) pairs and the creation of active radicals such as hydroxyl radicals (OH). The PEC decolorization kinetic data were analyzed using the first-order kinetic model and the Langmuir-Hinshelwood (L-H) model. The data indicates that the PEC degradation of MB molecules mainly occurred on the surface of the F-TiO2 photoelectrodes, and the MB molecules were discolored mainly by h+ (41.5%) and OH (46.5%). In addition, 8.2% of the MB molecules were discolored by other oxidative species, and 3.8% of the MB molecules were discolored by self-sensitized oxidation.

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