Constructing functional thermal-insulation-layer on Co3O4 nanosphere for reinforced local-microenvironment photothermal PMS activation in pollutant degradation

Photothermal catalysis of functional materials triggered by light-irradiation to local heating approach attracts growing attention, but one key detail affecting catalytic thermodynamic process was often ignored that thermal-conductive surface of functional materials directly contacting reaction solution easily delivers heat to the reaction system, leading to weakening heating effect in the interfacial local catalytic microenvironment. Herein, a functional low-thermal-conductivity layer that Mn-coupling porous SiO2 shell layer was constructed over the Co3O4 nanospheres. Specifically, SiO2 with porous channels introduced acts as the thermal-insulation layer to prevent the heat dissipation of the photo-heating core of Co3O4. More importantly, porous channel and inserted MnOx active species could further offer an additive special reaction microenvironment over the photo-heating core of Co3O4. Additionally, the introduction of Mn and structural remodeling through tailored annealing temperature (600–800 °C) can give improved catalytic hybrids abundant valence states and interfacial effects. A series of Co@Mn/m-SiO2 catalysts were fabricated based on the above control tactic. The Co@Mn/m-SiO2 catalysts exhibit superior activating ability for peroxymonosulfate (PMS) to degrade bisphenol A (BPA) and other pollutants including 2, 4-dichlorophenol (2, 4-DCP), phenol (PhOH), oxytetracycline (OTC), and tetracycline (TCN). Specifically, Co@Mn/m-SiO2-700 was shown to achieve complete degradation of 20 ppm BPA in less than 10 min under optimal conditions. In addition, we demonstrated that functional silica layer modified Co3O4 affords a better photo-heating effect compared to bare Co3O4 sphere in air or water, thereby contributing to a faster PMS activation efficiency. Besides, thermal treatment processing for Co@Mn/m-SiO2 catalyst makes the surface reactive species be optimized to generate more beneficial redox pairs and reach excellent photothermal catalytic efficiency in various pollutants treatment.