3D-honeycomb architectures evaporator toward mutual reinforcement of evaporation and catalysis for efficient freshwater harvesting

Solar-driven freshwater harvesting has emerged as an effective and sustainable technology to mitigate global water scarcity due to its high energy conversion efficiency. Nevertheless, achieving mutual reinforcement of photothermal and photocatalysis processes is in high demand because the contamination of harmful and highly concentrated volatile organic compounds (VOCs) will inevitably evaporate and condense alongside water. Herein, an integrated 3D-honeycomb fabric (NPPF) evaporator decorated with polydopamine (PDA), polypyrrole (PPy), and hydrotalcite (LDH) nanoflowers was designed innovatively by synergistically cooperating photothermal evaporation and advanced catalytic oxidation techniques. With periodically concave arrays, it can create the maximum level of light-trapping through multiple scattering and omnidirectional light absorption, thereby increasing its photothermal catalytic degradation ability. Meanwhile, introducing the LDH nanoflowers boosted the photothermal evaporation capacity of the NPPF evaporator. Therefore, it demonstrated high solar absorption efficiency of ~98.02% and an evaporation rate of ~2.02 kg m−2 h−1 under one sun. Furthermore, it can achieve superb degradation activity, especially for high-concentration VOCs, with efficiency of ~93.99%, surpassing most of the other evaporators reported previously. Besides, the outdoor experiment demonstrated its practicability. More importantly, it can remove tetracycline and phenol with efficiency of ~98.85% and ~ 92.06%. The advantages make this evaporator a promising representative for cooperative freshwater production.