Photothermally enabled MXene hydrogel membrane with integrated solar-driven evaporation and photodegradation for efficient water purification

Sustainable and energy-efficient water purification making use of solar energy is highly desirable to address water scarcity and pollution crisis. However, it remains a challenge to achieve full solar spectrum utilization with photothermal and photodegradation capability. Herein, inspired by the unique optical property of MXene, a novel assembly of MXene hydrogel membrane with synergistic photothermal and photocatalysis effect is proposed for integrated water purification. The MXene hydrogel membrane is fabricated based on the structure-directing of self-stacking MXene nanosheets and its abundant molecular interactions with the polymer matrix, polyvinyl alcohol (PVA), and the multifunctional layer-crosslinker, porphyrin. The obtained MXene hydrogel membrane exhibits fascinating physicochemical properties combining dynamic hydrophilic network of hydrogel and permeability of membrane, making it a preferred medium for both vapor generation and photodegradation. Moreover, calculation and experimental results illustrates the charge redistributions and coupling interactions between MXene and porphyrin, which imparts enhanced photothermal effect and photocatalytic activitiy. As a result, the MXene hydrogel membrane exhibits an high solar-driven water evaporation rate (1.82 kg m−2 h−1) and a photodegradation efficiency (90.5 %), rendering an integrated water purification capability under one sun irradiation. This work presents a feasible and effective route towards develop of MXene-mediated cooperative photochemical and photothermal solar energy conversion for sustainable water purification.