Excellent fog droplets collector via an extremely stable hybrid hydrophobic-hydrophilic surface and Janus copper foam integrative system with hierarchical micro/nanostructures.

As water shortages increase in semi-arid deserts and inland areas, the collection of fog has attracted tremendous attention in recent years. Different types of fog collectors have been widely reported in the past decade. Inspired by the creatures, a micro/nano-structured hybrid hydrophobic-hydrophilic surface was prepared via a simple hydrothermal method. In addition, the Janus performance was obtained using photocatalytic reaction. This hybrid hydrophobic-hydrophilic surface and Janus copper foam integrative system (HB-HL + JCF) may be of research significance because the preparation methods are environmentally friendly and economical. Next, special attention is paid to the systematic physical mechanisms of unidirectional transport and fog collection. In addition to these, the collection process of fog is analyzed in detail, and the optimal conditions for fog collection were selected by changing the sizes and tilt angles of the as-prepared copper foam. Compared to the original copper foam, the HB-HL + JCF exhibits a highly efficient fog collection (about 209% enhancement). Moreover, the experimental results showed that the HB-HL + JCF had excellent stability, and the wettability changes little under long-time ultraviolet light irradiation or multiple heating/cooling cycles. This work may provide insight into the fabrication of new fog harvesting materials and certain reference value for the development of advanced fog collectors for various purposes.