Dual S-scheme SnO2/TiO2(A)/TiO2(R) nanowires for visible-light-driven naphthalene complete degradation

Abstract

Ternary heterojunctions SnO2/TiO2(A)/TiO2(R) nanowires with excellent photocatalytic activity following dual S-scheme mechanism in the naphthalene visible-light-driven degradation were successfully prepared by a simple alkaline hydrothermal method for the first time in the paper. The physical and chemical properties were characterized by XRD, SEM, N2 adsorption–desorption isotherms, ICP, UV–vis DRS, FT-IR, TEM, XPS and PL emission spectra, and the photochemical properties were also conducted by Photocurrent response spectra, EIS and ESR techniques. The nanowires with about 50–500 nm in width and 10 μm in length would be obtained by the successful incorporation of tin species into the diphasic TiO2 framework. The integrated flexible membrane for the 10-STNBs nanowires can be easily peeled from the filter paper and it can be repeatedly bent for several times resulting from the nanowires disordered stacking layer by layer, and naphthalene can be completely degraded in the 220 min owing to the restricted recombination rate of photogenerated charge, lower electrochemical impedance and charge transfer limitation, lowest bandgap of 2.72 eV and weakest PL intensity when the ·O2– and ·OH species as the main active radicals with a dual S-scheme mechanism. The slight drop from 100.0 to 99.5 % of naphthalene degradation rate can be reached after repeated use for 10 times owing to the stable structure maintenance. This method can provide a valuable reference and potential promising catalyst for the industrial application in the naphthalene wastewater treatment.