Photothermal performance of carbon nanotubes in the visible and near-infrared regions: applications in water evaporation and destroying cancer cells

Direct conversion of solar energy into thermal energy by photothermal materials is the most efficient method among all solar energy conversion strategies. In this research, the photothermal performance of functionalized carbon nanotubes (CNTs) was investigated in both visible and near-infrared (NIR) regions (300–1000 nm), and their ability to evaporate water and also to kill cancer cells was investigated. CNTs with different concentrations of 0.03, 0.06, 0.25, and 0.5 g/L were dispersed in deionized water, and a maximum increase in the water temperature of 15 °C was measured in visible light. Also, a water surface evaporation rate of 0.6336 kg/h.m² with the photothermal conversion efficiency of 70.4% in the visible range was measured. The photothermal performance of CNTs in the NIR region was investigated with 808 nm laser radiation, and a water temperature increase of 46 °C with a conversion efficiency of 40.37% was measured. By increasing the laser power from 1 to 2 W/cm², the water temperature reached to 100 °C in less than 6 min. Also, the photothermal therapy performance of CNTs in killing HeLa cancer cells was investigated by the MTT method and found that CNTs can kill 93% of HeLa cancer cells within 10 min under laser radiation.‌

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