Assemble a new functional PEDOT-ZIS electrode for sustainable and efficient treatment of wastewater in photoelectrocatalytic system

Poly (3,4-ethylenedioxythiophene) (PEDOT), which served as photosensitizer and holes transport agent, was polymerized on ternary Zn-In-S film (ZIS) for enhanced photoelectrocatalytic (PEC) activity. The photogenerated electrons and holes can be effectively separated, which can enhance photoelectrocatalytic activity on methylene blue (MB) degradation. The MB decolorization and mineralization rate can reach 96 % and 53 % under the optimal degradation condition with applied voltage of -0.3 V and pH 4 under reaction time of 180 min. In addition, the PEDOT-ZIS composite electrode exhibited good stability after 5 consecutive cycles of experiments. Hydroxyl radical (·OH), superoxide radical (·O₂⁻) and singlet oxygen (¹O₂) were detected in the PEC system using PEDOT-ZIS as electrode. 2.37 × 10^-2 mmol·l^-1 of ¹O₂ was generated by PEDOT-ZIS composite electrode through photosensitization of PEDOT coating layer. Also 1.70 × 10^-2 mmol·l^-1·O₂- was produced through oxygen reduction by photogenerated electrons. In comparison, no ¹O₂ was detected in pure ZIS electrode system. More negative conduction band was obtained for PEDOT-ZIS composite electrode, which was more conducive to the generation of reactive radicals through electron reduction. Electrochemical impedance spectroscopy and photoluminescence spectra measurements reflected lower charge transfer resistance and recombination of electron-hole pairs in PEDOT-ZIS system.