Molecular engineering of a synergistic photocatalytic and photothermal membrane for highly efficient and durable solar water purification

Abstract

In recent years, the solar-driven interfacial evaporation system (SIES) has obtained a lot of interest as a potential solution to freshwater scarcity. However, the organic pollutant residues affected the practical application of the distillate generated by SIES. Herein, a solar interfacial membrane (AuNPs@g-C3N4/CMF) (AMF) for desalination and removal of multiple water pollutants was prepared by generating Au-doped carbon nitride (AuNPs@g-C3N4) directly on the carbonized melamine (CMF) through a co-calcination process. The designed membrane features excellent light absorption, efficient water supply, and low thermal conductivity. All the above advantages of the AMF membrane contributed to an outstanding evaporation rate (1.675 kg m-2 h-1) and high photothermal conversion efficiency (94.03%) under 1 sun irradiation. For seawater desalination, the membrane performed well in removing ions from simulated seawater and demonstrated good stability during long-term desalination. Meanwhile, the membrane still exhibits a high evaporation rate (1.24 kg m-2 h-1) even in a 10% salt solution environment. Owing to the photocatalysis capability of AuNPs@g-C3N4, the AMF membrane also performs effectively in the removal of organic dyes and formaldehyde.