Plasmonic coupling mediated photothermal membrane distillation with MXene-based heterojunctions for high-efficiency seawater desalination

Photothermal membrane distillation (PMD) presents a promising, eco-friendly and low-cost solution to address water shortage. Current PMD is still challenged by low solar energy utilization, limited mass transfer rate, poor membrane stability, and serious membrane fouling. Herein, we demonstrate that Ag@MXene heterojunction engineered membranes can achieve efficient desalination through photothermal membrane distillation. Theoretical calculations and experimental results prove that the plasmonic coupling effect of Ag@MXene enhances solar-thermal conversion efficiency, due to the promoted relaxation of photoexcited hot carriers. Meanwhile, the heterojunction structure promotes water molecules transfer within the interlayer channels. Consequently, the membrane achieves a significantly boosted total freshwater production rate (2.62 kg m −2  h −1 ) with a significant enhancement percent of 83.2 % and a high photothermal efficiency (77.0 %) under one solar illumination. Moreover, the Ag@MXene membrane possesses a superior durability in 72 h of continuous seawater desalination with an impressive ion removal efficiency of 99.95 %. The PMD membrane achieves a peak flux and an average flux of 21.53 and 12.08 kg m −2  h −1 in the outdoor test. This work offers a new approach for heterojunction engineered PMD membranes toward energy-efficient and sustainable freshwater production.