Constructing multi-functional carbon-based aerogels for highly efficient photo-thermal desalination and water purification

Interface solar-driven evaporators capture sunlight and concentration of heat at the vapor-liquid interface to efficiently evaporate water. However, challenges remain in the preparation of evaporators with a high evaporation rate and efficiency of photothermal conversion. Herein, an advanced carbon-based aerogel evaporator was designed by carboxylated multiwalled carbon nanotubes (MWCNTs-COOH) and cellulose nanofiber (CNF) entangling with each other as a backbone and in-situ polymerized polypyrrole (PPy) to constitute three-dimensional (3D) porous structure for highly efficient photothermal desalination and wastewater purification. The combination of MWCNTs-COOH with PPy reduces the energy gap (0.91 eV), endowing the aerogel with excellent photothermal conversion properties. The porous MWCNTs-COOH/PPy/CNF(CPCA) aerogel possesses an extremely low density of 0.048 g m⁻³ and excellent water transport capability, which exhibited a high water evaporation rate (2.48 kg m⁻² h⁻¹) and superior energy efficiency (90.2 %) under one sunlight intensity. The designed water evaporator can be stably and continuously applied in desalination and wastewater purification, and it is expected to be used for water purification to alleviate the worldwide water challenge.