Janus microbial membrane constructed by multiple biological self-assembly for photothermal conversion

Biological self-assembly as a kind of biological spontaneous behavior presents low energy consumption and high efficiency. In this work, biomass membrane is closely combined with carbon membrane derived from microorganism by biological self-assembly, forming Janus membrane (FAS-MC@M). The biomass-derived carbon membrane is endowed with superior photothermal conversion efficiency, also with the enhanced salt resistance via its hydrophobic nature and salt excretion domains. On the other hand, the biomass layer with good hydrophilicity and abundant capillary transport pipes ensure rapid water transfer to the Janus interface, conducing to stable heat exchange. The intrinsic micropores of the mycelium fiber can secure the reliable salt ion exchange between the tube water and bulk water during evaporation, which inhibit salt crystals formation as well. Meanwhile, biomass layer also reveals the relatively high thermal insulation properties, which can lower heat loss of the carbon membrane and improve the heat accumulation effect. For oily sewage, the biomass layer is also effective in protecting the photoheat exchange interface (carbon membrane) from oil pollution. In fact, the Janus evaporator in this work achieved 3.2 kg m-2h−1 evaporation rate under one solar intensity, showing desirable evaporation desalination potential.