Effects of Rare Earth Doping on Structural and Electrocatalytic Properties of Nanostructured TiO2 Nanotubes/SnO2-Sb Electrode for Electrochemical Treatment of Industrial Wastewater

The solvothermal synthesis technique was employed to successfully fabricate a series of rare earth doped SnO2-Sb electrodes on the TNTs array substrate, serving as anode material for electrocatalytic degradation of phenol. The electrode doped with rare earth elements demonstrated superior electrocatalytic activity and stability in comparison to the undoped electrode. The influence of adding rare earth elements (i.e., Gd and Nd) into the precursor solution on the structural and property of TNTs/SnO2-Sb electrodes was studied in detail. The results obtained from SEM and XRD indicated that, compared to TNTs/SnO2-Sb-Nd, TNTs/SnO2-Sb-Gd exhibited a finer grain size due to the smaller ionic radius of the Gd element. This facilitated its incorporation into the SnO2 lattice interior and inhibited grain growth, resulting in a significant decrease in particle size for exposing more active sites. The influence mechanism of rare earth doping on electrochemical activity was investigated through XPS, EPR, LSV, EIS and Hydroxyl radicals (•OH) generation tests. The results demonstrated that the enhanced electrocatalytic activity can be attributed to an increased generation of oxygen vacancies on the electrode surface, which act as active sites for enhancing the adsorption of oxygen species and promoting •OH generation.