Biomimetic Micro-Nanostructured Evaporator with Dual-Transition-Metal MXene for Efficient Solar Steam Generation and Multifunctional Salt Harvesting.

Solar-driven interfacial evaporation is one of the most attractive approaches to addressing the global freshwater shortage. However, achieving an integrated high evaporation rate, salt harvesting, and multifunctionality in evaporator is still a crucial challenge. Here, a novel composite membrane with biomimetic micro-nanostructured superhydrophobic surface is designed via ultrafast laser etching technology. Attractively, the double-transition-metal (VMo)CT MXene nanomaterials as a photothermal layer, exhibiting the enhanced photothermal conversion performance due to elevated joint densities of states, which enables high populations of photoexcited carrier relaxation and heat release, provides a new insight into the photothermal conversion mechanism for multiple principal element MXene. Hence, the (VMo)CT MXene-200 composite membrane can achieve a high evaporation rate of 2.23 kg m h under one sun, owing to the enhanced "light trap" effect, photothermal conversion, and high-throughput water transfer. Synergetically, the membrane can induce the directed precipitation of salt at the membrane edge, thus enabling salt harvesting for recycling and zero-emission of brine water. Moreover, the composite membrane is endowed with excellent multifunctionality of anti-/de-icing, anti-fouling, and antibacterial, overcoming the disadvantage that versatility is difficult to be compatible. Therefore, the evaporator and the promising strategy hold great potential for the practical application of solar evaporation.