NIR-triggered photocatalytic/photothermal/photodynamic water remediation using eggshell-derived CaCO3/CuS nanocomposites

The full utilization of sunlight and design of high-efficient and low-cost photocatalysts with robust stability for wastewater treatment is still a challenging task. Herein, we report an economic and simple strategy to prepare a novel photocatalyst by using eggshell as template and support. Rod-like Copper sulphide (CuS) nanoparticles are uniformly coated on the surface of porous eggshell to form CaCO3/CuS nanocomposite. Under NIR irradiation, the nanocomposite shows a high catalytic activity for 4-nirophenol (4-NP) reduction and strong photothermal ablation behavior against bacteria. A 98% degradation rate can be completed in 15 min, superior to that in the absence of Near-infrared (NIR) light irradiation. Bacterial inactivation ability is also closely related with photocatalyst concentrations and NIR power. A possible mechanism is suggested, which is attributed to the synergistic photocatalytic, photothermal, photodynamic effects. Our study indicates that waste eggshell not only can be used as an efficient support to immobilize nanoparticles, but also can act as reaction resource to provide active carbonate radicals (-CO3-), which play an important role on target degradation molecules.