Integration of bimetallic CuCo into N-doping SiC hollow nanoreactor for pollutant removal coupled solar-driven cleanwater regeneration

Abstract

Photothermal nanomaterials have showed great potential for development in simultaneous pollutant purification and freshwater recovery. In this study, a novel composite composed of hollow N-doping SiC porous hybrid network with the integration of CoCu bimetal species was constructed by a simple self-assembly and temperature-modulated approach. Such a hollow porous hybrid nanoreactor is endowed with abundant synergetic CuCo bimetallic reactive sites and polar pyrrolic N sites, which improves the enrichment of pollutants and intermetallic redox pairs. Ultrafine nanocrystals corresponding to Co2SiO4 over the hybrid framework can be evidenced by HRTEM technique. The experimental results showed that the optimal CoSiCu-6 degraded norfloxacin (NFX) by 90.7% in 10 min with a pseudo-first-order rate constant of 0.493 min−1, which was about 6.49 folds enhancement compared to Cu-free CoSi-6 counterparts, achieving a low reaction activation energy (18.02 kJ mol−1) during the reaction. Control experiments including anion interference and broad applicability for pollutants degradation were further explored, emphasizing the excellent performance of CoSiCu-6 in the practical contaminant removal. The mechanism study showed that, single linear oxygen (1O2) coupled with electron-transfer process work as the main activation routes dominating the degradation process. In addition, Co3+/Co2+/Cu2+ redox pairs and oxygen vacancies (Ov) play a key role in the PMS activation process. The obtained optimal catalyst was further explored for solar-driven photothermal interfacial water evaporation, showing a rational cleanwater recovery efficiency (∼1.3 kg m−2 h−1) from the polluted wastewater. In addition, monolith floatable evaporator was constructed by anchoring CoSiCu-6 onto a tailored melamine sponge foam via a calcium ion-triggered sodium alginate cross-linking strategy, affording an excellent evaporation performance (2.16 kg m−2 h−1) and coupled norfloxacin degradation efficiency (93.6%, within 5 min). This innovative monolithic evaporator made of CoCu integrated SiC hybrid nanosphere has a powerful dual function of rapidly degrading pollutants and facilitating solar-powered regeneration of contaminated wastewater due to its unique hollow porous structure and the CoCu bimetallic synergistic action that provides a rich set of reaction sites, which is promising for the treatment of complicated wastewater.