All-in-one solar-activated MXene@CuS membrane for advanced water purification

Abstract

Sunlight-driven interfacial water evaporation (SDIE) represents a promising approach for the sustainable generation of clean water. While the majority of existing studies have aimed at enhancing water evaporation efficiency, relatively little emphasis has been given on addressing the enrichment of oil/bacteria pollution and evaporated organic pollutants, particularly volatile organic compounds (VOCs), in the collected distilled water. In this work, MXene@CuS nanomaterials were synthesized via an HF-free method followed by hydrothermal treatment and incorporated into a composite membrane (MPCT) using a PVA-CMC hydrogel coating on melamine foam. The unique integration of MXene@CuS and PVA-CMC on melamine foam enabled outstanding performance, achieving 99% of oil/water emulsion separation efficiency and 99.99% photocatalytic degradation of wastewater containing VOCs and methylene blue, significantly surpassing the capabilities of most previously reported MXene-based catalysts. Moreover, the optimized MPCT membrane exhibited a water evaporation rate of 3.4 kg m⁻² h⁻¹ and achieved an evaporation efficiency of 98% under one-sun irradiation. Both the filtered freshwater and the evaporated water obtained through solar evaporation comply with the drinking water quality standards set by the World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA).