A cost-effective photothermal superhydrophobic coating with micro- and nano-graded structures for efficient solar energy harvesting

Solar collector coatings can solve the current energy shortage and environmental pollution by converting clean solar energy into thermal energy. However, once the coating is adhered to a liquid, the performance of the solar thermal conversion will be seriously affected. Here, a cost-effective photothermal superhydrophobic coating was designed by modulating the microstructure of a highly solar-absorbing material (MCN), followed by a simple spraying method combined with polyvinylidene fluoride resin (PVDF). The MCN in the coating provides excellent photothermal conversion performance, hence, the surface temperature of the coating can be rapidly increased to 97.5°C at 1 kW/m2. In addition, the coating achieves a water contact angle (WCA) of 155.79° due to the combined micro-nano structure of MCN and PVDF coupled with the low surface energy of PVDF. More importantly, the coating possesses excellent mechanical properties and can be applied to different substrates. This cost-effective photothermal superhydrophobic coating has promising applications in outdoor environments such as insulated tents and waterproof insulation packaging.