Self-assembly carbon dots for powerful solar water evaporation. (August 2019) - Hou, Qiao
Abstract: Solar-driven water vaporization is considered one of the most sustainable technologies to solve water scarcity. However, the advanced design solar absorber system is still required for highly efficient steam generation. Here we develop a novel system for water evaporation through assembly of carbon dots within microchannels of processed wood. Not only is a dual-layer structure including of heat barrier and water transport channel formed, but also the modulation of carbon dot energy structures in favor of photothermal conversion is realized synchronously. This system exhibits higher water evaporation rate and energy efficiency for solar to steam generation than other black photothermal sheets (e.g. carbon nanotube, graphene, graphene oxide). On the one hand, the constructed size-dependent vaporization enthalpy theory shows that the micropores are beneficial to reduce vaporization enthalpy of water. On the other hand, the presented direct evidences for the roles of oxidation functional groups in solar thermal evaporation demonstrate that hydroxyl groups can improve solar-to-heat efficiency. Therefore, tailoring pore sizes and surface functional groups could be an efficient method for solar-to-vapor systems. Graphical abstract: Solar-driven water vaporization system fabricated with carbon dots achieved solar-to-steam efficiency of 92.7% with an impressive evaporation rate of 2.27 kg m −2 h −1 under one sun irradiation.Image 1