Improving the Photo Electro Catalytic Degradation of Methylene Blue by Modified TiO2/ITO Photo Anodes

Abstract

TiO2 photoanodes have gained significant attention for the removal of organic pollutants through photoelectrocatalytic processes, with the aim of developing a cost-effective and efficient method for improving the degradation of pollutants in surface water. This study investigated the effects of adding titanium nanooxide (Degussa P25) containing 70% anatase and 30% rutile phases on the properties of nanostructured TiO2 photoanodes prepared on glass substrates (indium tin oxide (ITO)) using sol–gel/dip coating techniques The results obtained from ultraviolet–visible transmittance spectroscopy, electrochemical (EC) impedance spectroscopy, photocurrent, and atomic force microscopy analyses revealed that the addition of Degussa P25 improved the electrical conductivity of the TiO2/ITO anode and reduced the optical bandgap from 3.50 to 3.35 eV, while the size of the titanium oxide particles decreased to about 75 nm. The EC impedance spectra measurement confirms that the addition of titanium nanooxide Degussa P25 improved the electrical conductivity for TiO2/ITO anode. The photoelectrocatalysis (PEC) performance of the TiO2 photoanodes was investigated via the degradation of methylene blue (MB) under UVA light irradiation. The AB photoanode (with the addition of Degussa P25) exhibited excellent PEC performance, with 95.9% color removal efficiency and 63% total organic carbon (TOC) removal efficiency, compared to 92% color removal efficiency and 56% TOC removal efficiency for the A photoanode (without the addition of Degussa P25). The kinetic constants (k) were 134 × 10−4, 110 × 10−4 (min−1) for A and AB anodes, respectively, and the degradation of MB followed first-order kinetics for all anodes. The A and AB anodes were compared as electrodes for the degradation of MB using PEC, photocatalysis (PC), and EC technologies. Subsequently, The A and AB anodes were utilized as electrodes to compare the performance of PEC, PC, and EC technologies for the degradation of MB. The results showed that the AB anode exhibited higher efficiency in all PC technologies, with color removal (%) efficiencies of 95.9% (PEC), 33% (PC), and 21% (EC) compared to 92% (PEC), 28% (PC), and 19% (EC) for the A anode. Additionally, the photooxidation process had a 2.1% effect on the degradation of the initial MB concentration.