Fabrication of MXene@TiO2-CNT composite membranes for enhanced desalination through photothermal membrane distillation

A novel MXene@TiO 2 /CNT composite membrane was fabricated for efficient photothermal membrane distillation. • The optimized membrane showed high vapor flux and solar-vapor conversion efficiency. • The membrane shows outstanding long-term stability and efficient desalination for high-salinity feeds and real seawater. • CFD simulation confirms superior interfacial heat localization and uniform mass transfer for scalable PMD applications. The escalating global freshwater scarcity necessitates the development of energy-efficient and sustainable desalination technologies. Membrane distillation (MD) offers promise for treating hypersaline brines but suffers from high thermal energy demand and temperature polarization, limiting its practical application. Photothermal membrane distillation (PMD) has emerged as a viable alternative by leveraging solar-driven interfacial heating to enhance thermal efficiency. However, conventional PMD systems often exhibit limited water flux due to narrow light absorption, inefficient thermal management, and mass transfer resistance. In this study, we developed a high-performance composite membrane by integrating partially oxidized MXene@TiO 2 heterostructures with an interwoven carbon nanotube (CNT) network on a porous PTFE substrate. The MXene@TiO 2 nanocomposites were synthesized via controlled oxidation using peroxymonosulfate, which introduced TiO 2 nanoparticles as intercalating spacers to expand nanochannels and facilitate vapor diffusion. The resulting membrane demonstrated broad-spectrum solar absorption and exceptional solar-vapor conversion efficiency. Under simulated one-sun irradiation, the membrane achieved a vapor flux of 3.03 kg/m 2 ·h, representing a 332.9% enhancement over non-illuminated conditions. Long-term stability and effective desalination of high-salinity feeds were also demonstrated, highlighting the potential of this membrane for sustainable solar-driven water purification. Download: Download high-res image (389KB) Download: Download full-size image