Solar-enabled water remediation via recyclable carbon dot/hydrogel composites

Scarcity of clean water, due to population growth, global warming, and depletion of natural freshwater sources, is among the most formidable environmental challenges facing humanity. Accordingly, development of cost-effective and widely applicable technologies for water remediation and purification is extremely important and highly sought. We present a new strategy for water purification using a composite material comprising carbon dots (C-dots) encapsulated within a porous hydrogel. The hydrogel matrix allows significant water uptake, while the embedded C-dots constitute effective photothermal mediators, absorbing solar energy for enhanced water evaporation. The C-dots further bestowed greater thermal and mechanical stability to the hydrogel host. The C-dot/hydrogel composite exhibited good operating parameters, including a water evaporation rate of 1.4 kg m² h^-1 and solar-to-vapor conversion efficiency of 89%. It was applied for diverse water treatment applications, including water desalination and removal of heavy metal ions, detergents, and organic molecules from contaminated water. The C-dot/hydrogel construct is easily synthesized from inexpensive, biocompatible, and environmentally friendly building blocks, is recyclable, and may be employed in varied water purification applications.