In situ growth of polydopamine modified ZIF-L arrays on air-laid paper as flexible evaporator for efficient solar desalination

Abstract

The utilization of solar vapor generation for water purification plays a pivotal role in addressing the severe water scarcity crisis. However, it poses challenges due to inefficient light trapping and absorption limitations in solar thermal energy conversion. Here, we have strategically developed an array structured light trapping system with vertically grown, leaf-like zeolitic imidazolate framework (ZIF-L) nanosheets on flexible air-laid paper, accompanied by the catalytic effect of Co ions that result in oxidative polymerization of dopamine (DA) into pleated polydopamine (PDA) layers. This novel solution extends the propagation path of light in the trapping system through multiple scattering. Upon optimization, the P/ZIF-L@PDA-3 evaporator boasts an evaporation rate of 1.48 kg m−2 h−1 at 1 sun (1 kW m−2) irradiation and achieves an impressive solar vapor conversion efficiency of 94.5 %. In practical settings, the evaporation rate can reach 2.22 kg m−2 h−1 after 9 h with an average outdoor light intensity of 0.995 kW m−2. Our study presents an innovative approach to constructing a flexible evaporator with a light-trapping structure, providing immense potential for practical solar applications.