A composite Sb-doped SnO₂electrode based on the TiO₂nanotubes prepared by hydrothermal synthesis

A hydrothermal synthesis approach was adopted to embed Sb-doped SnO2into TiO2nanotubes to form a three dimensional electrode(TiO2-NTs/SnO2-Sb), and it was compared with the conventionally fabricated Ti/SnO2-Sb2O5electrode(Sb-doped SnO2coated Ti sheet) in terms of surface morphology, crystal structure, photoelectrochemical properties and organic degradation performances. It was clearly observed from SEM images that the TiO2-NTs/SnO2-Sb electrode had a compact surface and the Sb-doped SnO2oxide was embedded successfully into the TiO2nanotubes. The loading amount of Sb-SnO2in the TiO2nanotube electrode was therefore increased compared with that in the Ti/SnO2-Sb electrode, which is beneficial for the electrochemical performance. The hydrothermally synthesized electrode has much better and larger SnO2crystals than that prepared by the traditional dip-coating method according to the Scherrer's equation derived from the XRD analysis. Besides, the durability of the TiO2-NTs/SnO2-Sb electrode was tested to be 116 hours, which was much longer than that of the Ti/SnO2-Sb electrode (1.6 hours), suggesting a long service lifetime electrode was achieved through the hydrothermal method. A higher oxygen evolution potential leading to a preferred degradation of methyl orange in an electro-catalytic process was observed by using the hydrothermally-prepared electrode than that of Ti/SnO2-Sb electrode. The TiO2-NTs/SnO2-Sb electrode has a superior ability in coupling the advantages of photocatlysis and electrocatalysis, which was evidenced by the linear sweep voltammetry and the chronoamperometry tests. It was interesting to note that an irradiation from Xenon lamp originally has no effect on the probe dye's removal. However, as the same irradiation was introduced to the electrocatalysis process using the TiO2-NTs/SnO2-Sb electrode, the removal efficiency of the probe significantly increased form 15.7% to 26.9% in 2 hours, due to a synergetic effect.