Multibioinspired Design of a Durable Janus Copper Foam with Asymmetric and Cooperative Alternating Wettability for Efficient Fog Harvesting

Because of the water deficiency increase in deserts and inland areas, fog harvesting technologies are considered a charming sustainable approach to alleviate the shortage of freshwater resources. Nevertheless, the weak ability for fog capture, water transport, UV, and mechanical damage resistance are long-standing obstacles to realizing the whole fog harvest and water collection procedure via fog harvest materials. Here, inspired by the composition of mussels and the surface structure of porcupinefish, a Janus fog harvest copper foam (CF) comprising economical polydopamine (PDA)-like composition coating (tannic acid-aminopropyltriethoxysilane, TA-APTES) and porcupinefish-like structured hydrophobic materials [polydimethylsiloxane (PDMS) with tetrapod-shaped ZnO] are synthesized. The benefits of Janus CF composites lie in that they have asymmetric and cooperative alternating wettability, thus speeding up the fog harvest. More importantly, the Janus CF composite exhibited excellent mechanical durability and UV resistance. The application experiments show that the fog harvesting rate of Janus CFs is 1.70 g cm-2 h-1 owing to the asymmetric wettability and cooperative alternating wettability. Overall, this work elucidates the role of the Janus asymmetric-wettability CF with cooperative alternating wettability in efficient fog water harvesting and gives new insight into the application of constructing a highly efficient fog water collector.