Robust photothermal self-healing superhydrophobic coating based on carbon nanosphere/carbon nanotube composite

In this study, a photothermal superhydrophobic surface based on carbon nanospheres/carbon nanotubes (CNSs/CNTs) composite was fabricated, and the self-healing effect of its superhydrophobicity under solar irradiation was demonstrated. To investigate the chemical composition and elemental distribution of the coatings, infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS) mapping analyses were performed. The morphology, roughness and wetting properties of the coatings were characterized using field emission scanning electron microscopy (FESEM), confocal laser scanning microscopy (CLSM) and contact angle measuring instrument, respectively. The results showed that CNSs and CNTs synergically constructed peak-like microstructures and villi-like nanostructures with the assistance of polydopamine (PDA) and epoxy resin (EP), and the obtained superhydrophobic coating had a water contact angle (WCA) of 160.7° and sliding angle (WSA) of 4.0°. The coating can convert light energy into heat energy (T230s = 189 °C) in a short time under the irradiation of simulated sunlight (I = 20 A). The photothermal self-healing mechanism was analyzed by X-ray photoelectron spectroscopy (XPS). When the coating became superhydrophilic under the treatment of O2 plasma, the hydrophobic long chain provided by dodecyltrimethoxysilane (DTMS) migrated to the upper layer of the coating under the thermodynamic drive, thus realizing the self-healing of superhydrophobic properties.