Growth of TiO2/Ti-MOF nanorod array with enhanced photoabsorption and photocatalytic properties on carbon cloth for efficient auto-cleaning solar desalination

Abstract

Solar-enabled seawater desalination has attracted increasing attention for mitigating the freshwater crisis worldwide, while the practical applications are vitally restricted due to unsatisfactory photoabsorption and membrane contaminations from organic-matter adsorption and sea-salt deposition. To settle the above issues, herein we report the growth of TiO2/NH2-MIL-125(Ti) nanorod array with enhanced photoabsorption and photocatalytic properties on carbon fiber cloth (CFc) (abbreviated as CFc/TiO2/Ti-MOF) by a simple hydrothermal-solvothermal two-step process for efficient auto-cleaning solar desalination. CFc/TiO2/Ti-MOF exhibits super-hydrophilicity (contact angle of 0° at 5 s) and higher photoabsorption (89.5 %) due to the surface modification and light-trapping effect from TiO2/Ti-MOF nanorod array, compared with CFc substrate (contact angle of 118° at 8 s, photoabsorption of 86.3 %). When CFc/TiO2/Ti-MOF is immersed in the aqueous solution containing organic dyes as pollutant model, it can remove 76.4 % Rhodamine B (RhB), 94.1 % methylene blue (MB), 62.8 % tetracycline (TC) and 58.5 % ofloxacin (OFLX) in 120 min under one sun irradiation. Subsequently, such CFc/TiO2/Ti-MOF cloth is used to construct a hanging evaporator, and it exhibits high evaporation rate of 1.86 kg m−2 h−1 without the solid-salt precipitation, conferring long-term auto-cleaning evaporation. Therefore, this study provides some insights for designing novel photothermal/photocatalytic membranes for efficient auto-cleaning solar desalination.