Laser-Engineered Ti/RuO2–Sb2O4–TiO2 Anodes Enabling Energy-Efficient Electrochemical Degradation of Thiamethoxam in Flow Reactors

Abstract In this study, Ti/RuO2–Sb2O4–TiO2 anodes were synthesized using innovative rapid thermal treatment methods based on CO2 laser irradiation and hybrid microwave heating. Structural characterizations demonstrated that these rapid heating methods led to coatings that were more homogeneous, with reduced exposure of the Ti substrate, compared to conventional furnace calcination. The electrochemical responses showed that anode preparation using the laser and microwave methods resulted in an approximately 2-fold higher electroactive area and a 3-fold lower charge-transfer resistance, compared to the electrode prepared by the furnace method. Furthermore, the electrodes produced by the nonconventional methods showed markedly improved service lifetimes, highlighting the laser-prepared anode (37 h), with an increase of around 1 order of magnitude, compared to the furnace-prepared electrode. Based on this superior performance, the laser-prepared anode was scaled up from 2 to 56 cm2 and was applied in the electrooxidation of thiamethoxam (TMX) in a recirculating filter-press electrochemical flow reactor. The use of a turbulence promoter unexpectedly reduced the kinetics of TMX degradation (from 0.055 to 0.045 min–1), revealing a strong dependence of process performance on the flow configuration. Finally, the application of a modulated current strategy, adjusted to the instantaneous limiting current, substantially enhanced the kinetics of TMX degradation (0.055 vs 0.171 min–1), while significantly reducing energy consumption (25.5 vs 9.8 kWh m–3). Overall, the integration of laser-assisted synthesis, rational hydrodynamic design, and modulated current operation resulted in a robust and energy-efficient electrooxidation platform with clear potential for application in advanced water treatment systems.