Silver nanoparticles‐polydopamine‐wax gourd: An antimicrobial solar evaporator with enhanced steam generation

Solar-driven interfacial evaporation is an emerging environmentally-friendly technology to produce freshwater, but the current interface evaporators are restricted by their high cost, complex fabrication processes, and low resistance to environmental conditions. Here, a low-cost and high-efficient evaporator was prepared simply by modifying natural wax gourd with polydopamine (PDA) and silver nanoparticles (AgNPs). The prepared AgNPs-PDA-wax gourd exhibited excellent light absorption (>94%) in the whole solar spectrum (300-2500 nm). Under 1 sun illumination, the prepared evaporator achieved an extraordinary evaporation rate of 1.70 kg m−2 h−1 (efficiency of 83.21%), which was 3.78 and 1.21 times higher than the rates of natural wax gourd and PDA-wax gourd, respectively. Such excellent performance was mainly attributed to the synergic light-to-heat conversion capability between localized surface plasmon resonance effect from AgNPs and enhanced light-adsorption ability from PDA. Due to the presence of AgNPs, the final evaporator also displayed a fascinating antibacterial behavior for both E. coli and S. aureus even during evaporating actual lake water. Meanwhile, the AgNPs-PDA-wax gourd presented good durability during 10-cycled experiments, seawater desalination, dye water purification and some extreme conditions (acid, alkaline and freezing). These results suggested the great potential for future practical applications of such biomass solar evaporators.