MXene-PVA-TiO2-based photothermal-catalytic membrane with high structural stability for efficient desalination and photodegradation

Solar energy is regarded as the most attractive energy source for producing clean water and green energy, as well as for photocatalytic pollutants removal. MXene, a 2D photothermal material, has opened up new opportunities in solar energy harvesting due to its unique properties. However, it has limitations, such as strong oxidation and degradation tendencies, that affect its stability. To address these challenges, herein we fabricated a highly stable MXene-PVA-TiO2@PVDF Janus membrane and tested it in an advanced photothermal-catalytic membrane distillation (PMD) system. The modified MXene-PVA-TiO2@PVDF membrane demonstrated superior photothermal desalination flux (1.23 kg/m2h with 99.9% salt rejection) and efficient photodegradation capacity (methylene blue removal rate > 95%) under 1 sun irradiation. The superior photothermal desalination efficiency of the prepared membrane is attributed to the wide-spectrum optical absorption and exceptional light-to-heat conversion characteristics of MXene, while a substantial enhancement in the photodegradation performance is ascribed to the formation of the MXene-TiO2 2D/3D hierarchical structure acting as a direct Z-scheme photocatalyst. The chemical and mechanical strength was significantly enhanced due to the robust 2D network structure of MXene-PVA. Overall, this study demonstrates the feasibility of synergetic photothermal-catalytic membrane distillation and the promising prospects of MXene materials in this field.