Surface self-assembled multi-layer MWCNTs-COOH/BN-PDA/CF for flexible and efficient solar steam generator

Many new laboratory-scale photothermal conversion materials have been developed for purification or desalination but developing easy-to-manufacture, low-cost and scalable materials with high efficiency of solar energy to thermal energy still faces great challenges. Herein, we provided a simple and effective method for self-assembly of dopamine-modified boron nitride (BN-PDA) and carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) layers on cotton fabric (CF), and assembled a solar steam generator by using the as-prepared composite cotton fabric as photothermal layer, cotton yarns (CYs) as water supply channel, and thermally insulated polystyrene (PS) foam as a supporting material. This solar steam generator exhibited a superior evaporation rate of 1.55 kg m −2 h −1 and an excellent photothermal conversion efficiency of ∼83.66% under 1.0 sun irradiance (1.0 kW m −2 ), with optical absorption up to 93.50% in the wavelength of 300–2500 nm. Meanwhile, excellent quality of freshwater from seawater and dyeing wastewater was also demonstrated. Different from other solar steam generator systems, this assembled fabric is cost-effective and readily available, suitable for large-scale industrial applications. Notably, the results show that multi-layer structure imparts it with outstanding mechanical flexibility and robustness, making it a potential candidate for fresh water supply in remote, off-grid or water-contaminated areas.