Fabrication of Nano-Structured Stacked Sphere SnO2-Sb Electrode with Enhanced Performance Using a Situ Solvothermal Synthesis Method

Abstract

A titanium-base nano-coating Sb-doped SnO2 electrode with a nano-scaled sphere-stacking structure was successfully fabricated using a solvothermal synthesis approach to enhance electrochemical performance through the formation of a nano-sized catalyst layer. Based on scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, the nano-coated SnO2-Sb electrode had very small (23 nm) catalyst grains that had a stacked sphere appearance, and thus a much greater specific surface area than the control electrode (SnO2-Sb prepared by a dip-coating method, 106 nm grain size). X-ray photoelectron spectroscopy (XPS) analysis showed that the nano-coated electrode possessed a higher concentration of oxygen vacancies, which provided many more active centers for the formation of adsorbed Oxygen (Oads), which increased the production of •OH radicals and therefore the catalytic activity of organic pollutant degradation. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) showed that the electrode with a nano-structure coating had a higher oxygen evolution potential (2.1 V, vs. Ag/AgCl) and smaller charge transfer resistance (49 Ω) than the control (1.95 V and 93 Ω). A kinetic analysis of the electrochemical degradation of phenol showed that the first-order kinetic rate constant for the nano-coated electrode was 1.72 times higher than the control. Accelerated service life testing showed that the stability of this novel fabricated electrode was 15 h, which was nearly 11 times longer than that of non-nano SnO2-Sb electrode.