Electrocatalytic nanocomposite flow-through porous electrodes with sputter-coated Cu/Co nanoparticles for degradation of waterborne perfluorooctanoic acid

The ubiquitous perfluorooctanoic acid (PFOA) exhibits remarkable persistence in the natural environment and has multiple potential toxic effects, posing a serious threat to human health and life safety. However, PFOA can hardly be effectively removed by conventional water treatment processes. In this study, we propose a novel electrocatalytic nanocomposite flow-through porous electrode prepared via sputter-coating of Cu and Co nanoparticles on a carbon felt (CF) substrate for the degradation of waterborne PFOA. A series of bimetallic Cu/Co@CF electrodes were successfully prepared, and the nanoparticle coating thickness and loading ratio were optimized. On the basis of systematic characterizations and degradation tests, the 4-nm-thick coating with a 1:1 Cu/Co ratio was determined to be the optimum coating recipe, and the corresponding Cu/Co@CF-T2 electrode achieved the highest PFOA removal of ∼ 44 % at a very low energy consumption of 0.11 kWh·m⁻³·order⁻¹ within 150-min treatment, exhibiting a superior efficiency compared with related studies in the literature. Mechanism analyses revealed that the PFOA degradation could be primarily attributed to the h⁺-based direct electron transfer (69.15 %), ·OH oxidation (41.63 %), and ¹O₂ oxidation (37.8 %), with the h⁺ being the most dominant degradation mechanism. Long-term stability tests indicated a slight decrease in removal efficiency after three 150-min cycles, yet the composite electrode maintained a 32.02 % removal rate at competitively low energy consumption, suggesting promising potential for future research and application development, particularly in wastewater treatment involving perfluorinated compounds.