One-pot pyrolysis and enhanced efficient solar evaporation of Cu/Cu2O/biochar

Solar water evaporation has attracted increasing attention owing to its clean water production applications. In comparing the intensive studies about the synthesis and applications as photothermal materials for biomass-based materials, less research is available on copper-biochar composites, let alone on their application in solar water evaporation. Moreover, previous reports have shown that copper-carbon hydrogel and graphene composites were greatly limited by the complexity and economy of fabrication, which hindered their mass production in solar water evaporation. In this work, Cu/Cu2O/biochar was synthesized by a facile one-pot pyrolysis process, since biomass carbon fulfills most of the properties required for the photothermal material. Waste tobacco stem was used as both the carbon source and reducing agent. The obtained materials possess great hydrophilic, good light absorption properties, and superior light-to-heat conversion. Specifically, these properties give the material an evaporation rate of 2.01 kg m−2 h−1 with a photothermal conversion efficiency of 79.7%, which is 6.48 times higher than that of pure water and 1.60 times as much as the direct carbonized tobacco stem. This work will provide the impetus for the design concepts and functionalized applications of solar thermal hybrid materials to enhance solar water evaporation.