Heat loss and water transport capacity regulation in hybrid evaporators

Abstract Solar interface evaporation technology, as a green and low-carbon water treatment solution, faces the core challenge of how to co-optimize photothermal conversion, water transport, and energy management through material design. Hydrogels have attracted significant attention for their hydrophilic networks and unique water molecular states in the field of solar interface evaporation. However, the mechanisms behind their improvement and efficiency enhancement remain unclear. We demonstrated that biochar doping improves the photothermal performance of hydrogels, regulates water absorption and transport, and reduces evaporation enthalpy. The dual photothermal and non-photothermal pathway enhancement mechanisms of functional groups are revealed. It is illustrated that the interaction between biochar and polymer chains changes the pore structure of hybrid hydrogels, promoting light absorption and water transport. Furthermore, the surface functional groups of biochar interact with hydrogen bond networks, increasing IW/FW and effectively enhancing water evaporation capacity. By combining enhanced photothermal performance, hydrophilicity, water transport capabilities, and lowered evaporation enthalpy, the incorporation of biochar comprehensively boosts the evaporation rate of hybrid hydrogels. Graphical Abstract