Coupling ultrafine plasmonic Co3O4 with thin-layer carbon over SiO2 nanosphere for dual-functional PMS activation and solar interfacial water evaporation

Photothermal materials afford growing interest in environmental governance, especially for addressing complicated environmental issues including the purification of wastewater and regeneration of freshwater together. Here, we constructed a dual-functional photothermal nanosphere by integrating ultrafine plasmonic Co3O4 (∼10 nm) into an N-doping carbon layer over silica nanosphere (SiO2@Co/C). Biocompatible dopamine coating induces the incorporation of Co precursor and activity optimization of metal species over the SiO2 nanosphere during the synthetic process. In this way, the SiO2 nanosphere maintains the stable configuration of the carbon coating thin layer to accommodate the local interfacial Co3O4 catalytic active substances. Impressively, this catalyst also owns a well-developed interconnecting N-containing network structure, unconventional redox cycle pair of Co(II)/Co(III), and significant metal-carbon interaction. A controlled thermal procedure (500–800 °C) was implemented to tune the optimized activity state of the catalyst. Under these merits, advanced oxidation process (AOPs) through activating persulfate by the obtained materials to degrade organic pollutants was performed in the presence/absence of sunlight, further validating the appreciable photothermal effect to improve the catalytic thermodynamic behavior. The reaction parameters ad anion interference were studied in detail, and SiO2@Co/C-600 can completely degrade bisphenol A (BPA) (30 mg L-1) with a high reaction rate constant of 0.722 min-1 and a low reaction activation energy of Ea (19.4 kJ/mol), and also shows superior mineralization activity for some stubborn pollutants, including oxytetracycline (OTC), 2,4-dichlorophenol and tetracycline (TC) through the reinforced photothermal approach. Besides, SiO2@Co/C-600 shows multiple functions in interfacial solar water evaporation application (1.36 kg m-2 h-1, 81.59 %), revealing great potential value of purification and regeneration of water in the complex pollution condition. This work gives the possibility for the next-generation versatile and competitive photothermal environmental governing materials.