Effective solar distillation with thermal concentration and anti-fouling wick

Thermal concentration-enhanced solar steam generation provides an energy-efficient and cost-effective way of water distillation by avoiding concentrating optics. In this study, we present a self-cleaning and reliable solar distillation device which has two key parts: a solar absorber for harvesting sunlight and a wick for supplying water. The solar absorber, made of a self-cleaning nanostructured copper substrate, is mounted between the transparent cover and floating insulation layer. The wick, made of nanostructured copper foam, is inserted through the floating layer for capillary pumping of water and continuous steam generation, similar to the upward water transpiration of trees. Both the top substrate and center foam wick are coated with titanium dioxide (TiO2), which renders the steam generation device self-cleaning and highly resistant to organic fouling in contaminated water as well as corrosion. Owing to the spectral selectivity of the solar absorber and high thermal concentration, the absorber surface becomes hot and enables effective evaporation of water in the porous wick. Our lab experiments show that the proposed device has outstanding and stable solar steam generation efficiency under one sun illumination. The proposed scalable devices promise great potential for both large-scale and portable water distillation in rural areas or off-grid islands.