Multilayer hollow microsphere-based Janus composite membrane for continuous solar evaporation via synergistic photothermal conversion and thermal energy storage

The intermittent nature of solar energy supply causes photothermal materials in interfacial evaporation systems to be unable to achieve continuous and stable photothermal conversion and water supply functions. To this end, this paper constructs a Janus composite membrane (MSHS@TDA@PAN) with both photothermal conversion and thermal energy storage capabilities through electrospinning. In MSHS@TDA@PAN, MgO/Pt multi-shell hollow microspheres impregnated with tetradecylamine (TDA) form a hydrophobic photothermal layer, while hydrophilic polyacrylonitrile (PAN) nanofibers act as a water-transporting layer, together driving efficient photothermal interfacial evaporation. It achieves an intrinsic light absorption of 80.7 %, a photothermal conversion efficiency of 79.83 %, and a phase change enthalpy of 90.7 J·g −1 . Experimental results show that the average evaporation rate of the photothermal membrane over one phase change cycle (One hour each for solar irradiation and dark field) is increased from 2.402 kg·m −2 of the membrane without phase change materials to 2.67 kg·m −2 . It can increase the production of fresh water by 3.24 kg·m −2 ·d −1 . Especially under no-light conditions, the evaporation rate of MSHS@TDA@PAN is 2.1 times that of the control group, which significantly alleviates the performance attenuation caused by intermittent illumination. In conclusion, MSHS@TDA@PAN effectively solves the intermittency problem of solar energy utilization through the synergistic mechanism of photothermal conversion, thermal energy storage and continuous heat release. It has application prospects in the fields of continuous seawater desalination and photothermal utilization.