Compositing ultrafine CoFe2O4 spinel with porous silica as catalyst for photothermal PMS activation and interfacial water evaporation

Although spinel oxides have been promising in advanced oxidation processes (AOP), multidimensional coupling via bimetallic redox cycles and photothermal synergy is still rare in AOP and environmental governance. Here, ultrafine plasmonic CoFe2O4 spinel nanoparticles (∼20 nm) were composited with porous silica and followed by a tuned thermal treatment procedure (600–900 °C) in N2 condition to obtain bimetallic nanocomposites. The resulting catalysts exhibited significant active interfacial effects and an increased proportion of Co (II) species in the spinel structure after the calcination process. The CoFe/SiO2-8 nanocatalysts effectively showed significant advantages in size structure and valence modulation compared to CoFe2O4 alone, and the prepared catalysts showed great potential for multiphase PMS activation with better photothermal effects. In addition, the introduction of SiO2 in the CoFe/SiO2-8 catalyst allows a higher activation efficiency of PMS during the catalytic degradation of bisphenol A. We also demonstrated that under photothermal (a simulated sunlight) conditions, 30 ppm BPA can be completely degraded within 30 min by coupling the photothermal effect with the catalyst, which is significantly better than the catalytic degradation behavior of only catalyst-participated BPA, achieving a promotive thermodynamic behavior and conversion efficiency. More importantly, solar-driven interfacial water evaporation by virtue of CoFe/SiO2-8 was explored to identify the practical potential possibility for the regeneration of freshwater from the polluted water resource.