Preparation and characterization of a TiO2-NT/SnO2–Sb tubular porous electrode with long service lifetime for wastewater treatment process

Abstract

The broad application of highly electrocatalytic SnO₂–Sb electrodes for wastewater treatment is limited by their short service lifetime. Herein, a novel substrate structure, tubular porous titanium, was applied to prepare a TiO₂-NT/SnO₂–Sb electrode, which could greatly improve the stability of the electrode for electrochemical oxidation process. Based on the analysis conducted using a field emission scanning electron microscope (FE-SEM), linked with an energy dispersive spectrometer (EDS), it was demonstrated that a solid solution between Sn and Sb presented a smooth surface of the tubular porous electrode. The crystalline structure and chemical composition of the electrode coating are determined by X-ray diffraction (XRD). Accelerated service life test reveals that under the 0.2 A cm⁻² current density in a 0.5 M H₂SO₄ solution, the TiO₂-NT/SnO₂–Sb tubular porous electrode has the longest accelerated service lifetime of 68.9 h, which is 10.9 times that of the TiO₂-NT/SnO₂–Sb plate electrode. Cyclic voltammetry curves (CVs) and linear sweep voltammetry curves (LSVs) reveal the enhanced electroactive surface area and higher oxygen evolution potential (OEP = 1.85 V vs. Ag/AgCl) of the electrode. Moreover, the TiO₂-NT/SnO₂–Sb tubular porous electrode has the larger outer voltammetric charge q*. During the electrochemical oxidation of pyrimidine, the tubular system constructed using the TiO₂-NT/SnO₂–Sb tubular porous electrode as the anode also exhibited best electrocatalytic performance, and 97.9% pyridimine removal efficiency and 79.4% COD removal efficiency at 6 h were achieved.