Constructing core@shell structured photothermal nanosphere with thin carbon layer confined Co-Mn bimetals for pollutant degradation and solar interfacial water evaporation

Photothermal material applied in environmental governance has attracted growing attention. By combining the Stöber method and dopamine-triggered coating strategy, Co-Mn precursor was in situ incorporated into the polydopamine (PDA) layer over the surface of silica cores. Afterwards, a unique photothermal nanosphere with SiO 2 core and thin carbon layer and dual Co-Mn oxides shell was allowed to form by sequential heat treatment in the inert atmosphere (SiO 2 @CoMn/C). The bimetallic fraction of Co/Mn in the carbon layer and post-treatment calcination temperature was comprehensively tuned to optimize the peroxymonosulfate (PMS) activation performance of the catalyst. The state of bimetallic species was studied including their physical distribution, chemical valence, and interplay by various characterizations. Impressively, Co oxides appear as dominant monodispersed nanoparticles (~ 10 nm), while Mn with cluster-like morphology is observed to uniformly distribute over thin-layer carbon and adhered to the surface of SiO 2 nanospheres (~ 250 nm). The calcined temperature could tune the oxidized state of Co species, leading to the optimization of the catalytic performance of introduced dual metal species. As a result, this obtained optimal catalyst integrated the advantages of exposed bimetallic CoMn species and N-doped thin carbon to deliver excellent catalytic PMS activation performance and photothermal synergetic catalytic mineralization ability for diversiform pollutants. Further reactions condition controls and anion interference studies were conducted to identify the adaptability of the optimal catalyst. Moreover, the application of solar-driven interfacial water evaporation using optimal SiO 2 @Co 3 Mn 1 /C-600 catalyst was explored, showing a high water evaporation rate of 1.48 kg·m −2 ·h −1 and an efficiency of 95.2%, further revealing a comprehensive governance functionality of obtained material in the complex pollution condition. Graphical Abstract