Interfacial solar steam generation by sawdust coated with W doped VO2

Abstract

Interfacial solar steam generation (SSG) has emerged as a promising solution to address the global challenges of water scarcity. Herein, for the first time, by pressing micro-scale sawdust into a polystyrene mold using a manual hydraulic press and enclosing it in an aluminum grid (S/Al), a substrate for SSG was made. Adjusting the porosity of the SSG device has a significant effect on the evaporation performance due to its potential in regulating the transfer of bulk water to the evaporation surface and controlling the thermal conductivity of substrate. The optimal sawdust-based photoabsorber with a 62% porosity represented 59% evaporation efficiency under 2.2 kW m−2. In addition, to improve the photothermal performance for the first time, vanadium dioxide nanoparticles doped by tungsten (W3-VO2) as a photothermal layer on the sawdust-based substrate were used. The results were compared with those of carbonized sawdust-based substrate supported by black aluminum grid (S/C/Al–B). The excellent performance belonged to S/Al/W3-VO2 device with 90% evaporation efficiency under 2.2 kW m−2 which was 3.3 and 1.2 times greater than pure water and S/C/Al–B, respectively. The concentration of four ions of Na+, Mg2+, K+, and Ca2+, which are responsible for the salinity of water, in the collected seawater after condensation of vapor decreased by about three orders of magnitude. Due to high performance, environmentally friendly, cost-effectiveness, and availability of the proposed device, the S/Al/W3-VO2 photoabsorber can be used in remote areas for large-scale applications.