Rational design of “ship-in-a-bottle” evaporator with integrated solar evaporation and photocatalytic degradation for sustainable water treatment

Solar interfacial photothermal-catalytic water evaporation is an emerging method for obtaining clean water from polluted water. However, many studies overlook the crucial aspect of clean water recovery. This study develops an interfacial photothermal-catalytic water evaporator (Carbon felt/TiO₂-Expandable polyethylene, CF/TiO₂-EPE) inspired by the “ship-in-a-bottle”. The strategy confines TiO₂ to the pore structure of CF to maintain its nanoscale size and form a macroscale structure, providing more reaction sites for photocatalysis and increasing the number of incident light reflections. Additionally, the reduction of CF pore size enhances the capillary effect, resulting in stable water transport. These characteristics endow CF/TiO₂-EPE with excellent photothermal synergistic purification performance. Specifically, CF/TiO₂-EPE removes 92.5 % of the antibiotic ciprofloxacin from wastewater. Meanwhile, a novel evaporation device is designed to enhance vapor escape and collection through micro-airflow, reducing the loss of light and heat energy, resulting in a clean water yield of up to 1.81 kg m^-2h⁻¹. Compared to traditional water evaporation devices, its clean water recovery rate increased by 10.5 times and 13.7 times, respectively. Furthermore, this photothermal-catalytic water evaporation system can produce 46.43 kg m⁻² of clean water under 24-hour continuous operation with low energy consumption, sufficient to meet the daily water needs of 11 adults. The rational design of photothermal-catalytic structures and the development of new water evaporation devices are of great importance for obtaining clean water from polluted water efficiently and sustainably.