Reduced Red Mud as the Solar Absorber for Solar-Driven Water Evaporation and Vapor-Electricity Generation.

The emergent solar-driven water evaporation technology provides a reassuring scheme for red mud (RM) utilization in environment and materials science. With fewer restrictions on raw materials, wide availability of sheer quantity, and high complexity in chemical composition, the RM may be a promising candidate for solar absorbers. Here, we developed a novel solar absorber with reduced RM. It features favorable light absorption and photothermal conversion ability using biomass pyrolysis. When added to the polyvinyl alcohol and chitosan gel substrate, the light absorptance can reach 94.65%, while the corresponding evaporation rate is as high as 2.185 kg m-2 h-1 under an illumination density of 1 kW m-2. We further demonstrated its potential as an efficient solar absorber in the solar-driven water evaporation and the thermoelectric device to realize the stable and efficient coproduction of vapor and electricity.

Self-Cleaning Integrative Aerogel for Stable Solar-Assisted Desalination.

The solar-assisted desalination generator (SADG) shows great potential for solving water scarcity problems. However, salt precipitation and accumulation is still a challenge for SADG, which slows down solar steam generation performance of evaporator during operation. Here, a facile integrative evaporator featuring stable and high evaporation performance breaks this bottleneck. By using a rational design in which amorphous carbon particles are evenly composited within the porous chitosan aerogel, the evaporator not only integrates excellent light absorption, heat management, and water transportation abilities but also endows a large vapor escape space. Upon desalination, salt concentration ingredients between carbon particles and chitosan membranes can be quickly balanced by water transport in interconnected chitosan chains, and thus salt precipiation on the evaporator surface would be avoided. Compared to other salt-rejection evaporators, the integrative evaporator can operate in 3.5 wt% brine for 60 days without salt precipiation and exhibits a stable evaporation rate (1.70 kg m-2 h-1), indicating its potential for practical applications in seawater desalination and the harvest of clean drinking water.