The assembly of a polymer and metal nanoparticle coated glass capillary array for efficient solar desalination

Abstract

Novel solar desalination technology has emerged as one of the most efficient approaches for the production of freshwater, owing to its low energy consumption, sustainability, environmental friendliness, and higher energy conversion efficiency. In this work, we report the preparation of a novel solar steam generator via the facile assembly of a polydopamine (PDA) and Pd nanoparticle (PDN) coated glass capillary array (GCA) as a top vaporization layer, using multilayer cotton fibers as the bottom thermal-insulation layer. The GCA-based solar generator features the thermal insulation properties of cotton fiber with low thermal conductivity (0.0695 W m⁻¹ K⁻¹), superior light absorption performance (over 80% for PDA and over 99% for PDN), and continuous unidirectional water transportation. Energy conversion efficiencies of 84.8% for PDA-GCA and 89.8% for PDN-GCA were achieved under 1 kW m⁻² illumination, which are comparable with the best performance shown by a salt-resistant solar evaporator that has been reported so far. Compared with biomass- or organic-polymer-based solar generators, which usually suffer from a number of drawbacks, such as low reproducibility and being putrescible or nondurable in a water environment, the inorganic nature of GCA endows it with long-term corrosion stability. In addition, the straight and hollow cylindrical shape of the GCA with low tortuosity gives it superior salt-rejection performance via the resolution of the crystalline salt and the transferring of it back to the solution based on its inherent capillary effect, thus showing great potential for real solar desalination via the combination of simple, scalable and cost-efficient assembly and fabrication.