MXene-decorated flexible Al2O3/TiO2 nanofibrous mats with self-adaptive stress dispersion towards multifunctional desalination

Abstract

Solar-driven interfacial evaporation has shown great promise for desalination due to its high photothermal conversion efficiency. However, for interfacial evaporation, the evaporator must have superior mechanical quality and strong thermal stability. To this end, ceramic nanofibrous mats with good mechanical strength can serve as a stable substrate for desalination. Herein, with the aid of finite element analysis, flexible Al₂O₃/TiO₂ nanofibrous mats with robust mechanical properties are fabricated, where the stress dispersion greatly facilitates the Al₂O₃/TiO₂ nanospheres to be uniformly dispersed into the mat. The flexible nanofibrous mats exhibit a high tensile strength up to 2.18 MPa. Afterward, a two-dimensional (2D) Al₂O₃/TiO₂/MXene mat is constructed by a simple drop-casting method. Interestingly, the evaporation rate of the Al₂O₃/TiO₂/MXene-2 mat reached 1.43 kg m⁻² h⁻¹, and the light-to-vapor energy conversion efficiency can reach 102% at a power density of 1.0 kW m⁻². To measure the desalination efficiency, five ion concentrations in the collected water were found to be well below the safe salinity levels defined by standards set by the World Health Organization and U.S Environmental Protection Agency. Utilizing basic origami technology, the three-dimensional (3D) photothermal evaporator was integrated with the 2D mat due to its flexibility and ductility. Additionally, the evaporation rate increased to 1.61 kg m⁻² h⁻¹. This study is critical in the design of composite ceramic nanofiber materials with high flexibility and photothermal conversion efficiency for multifunctional desalination.