Star-Shaped Bionic Evaporator with Enhanced Marangoni Convection for Achieving Zero Liquid Discharge Desalination of...

Solar-driven interfacial evaporation (SDIE) is a promising technology for freshwater production, but severe salt accumulation remains a critical bottleneck for its long-term stability and the realization of zero liquid discharge (ZLD). Inspired by plant guttation through leaf tips or edges and the morphology of morning glory flowers, a biomimetic pentagram-shaped Janus evaporator (PCMF@STAR) was fabricated. Experiments and simulations consistently demonstrate that the PCMF@STAR synergizes thermal and solute gradients to drive co-directional Marangoni convection, overcoming the issue of mutually offsetting thermal and solute flows in conventional evaporators. This hydrodynamic synergy dramatically expands the range and intensity of convection, driving directional salt crystallization along the edge ridges while maintaining a clean photothermal interface. Consequently, in highly concentrated 20 wt % brine, PCMF@STAR achieved a superior evaporation rate of 3.28 kg m-2 h-1 and a salt collection rate of 270 g m-2 h-1, outperforming state-of-the-art systems by 167% and 342%, respectively. Furthermore, outdoor tests show freshwater yield of 13.95 kg m-2 day-1 and salt collection rate of 1710 g m-2 day-1, satisfying the drinking requirements of seven adults. This low-cost and scalable evaporator provides a reliable solution for ZLD and sustainable mineral recovery in complex environments.