Understanding the effect of the high hydrophobicity of the laser-prepared Ti/SnO2–Sb–La2O3 anode on its electrocatalytic properties

Abstract

SnO₂-Based materials have attracted much attention in the electrochemical oxidation field due to their high electrocatalytic activity. However, efforts are still required to improve their physical and electrochemical properties. Here we employed a CO₂ laser thermal process, as a substitute to conventional furnace heating, for the synthesis of two SnO₂-based anodes–Ti/SnO₂–Sb₂O₅ and Ti/SnO₂–Sb–La₂O₃. Compared with anodes made using conventional heating, the laser-prepared anodes show a more compact surface and a change from hydrophilic to super-hydrophobic wetting properties. Energy-dispersive X-ray spectroscopy and X-ray diffraction data reveal the uniform distribution of Sn, Sb, and La, as well as the formation of the desired oxides, respectively. The oxidation state and chemical composition were confirmed by X-ray photoelectron spectroscopy. Notably, the laser-prepared anodes exhibit a positive shift in the oxygen evolution overpotential, especially for the Ti/SnO₂–Sb–La₂O₃ anode, and a 2-fold reduction in the charge transfer resistance. The electrochemical degradation of 4-nitrophenol (4-NP) was investigated in aqueous solutions by UV-Vis spectra employing all anodes produced. The results showed that laser-prepared Ti/SnO₂–Sb–La₂O₃ displays the highest degradation efficiency at the lowest energy consumption. Also, a mechanism for the 4-NP oxidation at the SnO₂-based anodes under the current working conditions is proposed. Finally, the notable reduction in processing time and energy spent using laser heating makes it a feasible alternative to produce SnO₂-based anodes. Their improved properties enhance the potential of these anodes to be applied in the electrochemical treatment of polluted waters.