Boosting solar-powered interfacial water evaporation by architecting 3D interconnected polymetric network in CNT cellular structure

Photothermal hydrogel, with an inherently modifiable hydrated network, has been widely demonstrated as a promising candidate for efficient water treatment. However, there are still great challenges in architecting abundant interfacial mass transfer channels and avoiding excessive polarity interaction in polymeric hydrogels. Here, a 3D interconnected topological porous hydrogel was proposed to enable cellular carbon nanotube (CNT) structures filled with hydrophilic and thermosensitive nanonetworks via infiltration and crosslinking of polyvinyl alcohol (PVA), polyethyleneimine (PEI) and carbon black particles (CBs). A detailed comparative investigation revealed that hosting with CBs/PVA/PEI polymeric nanonetworks in CNT cellular structures facilitated the interfacial dehydration and the decrease of evaporation enthalpy, confirming that such a novel topological structure leaded to a remarkable increase in hydratable and heatable interfaces. In this regard, the obtained hybrid hydrogel achieved a high water evaporation rate of 3.55 kg m−2h−1 with an efficiency of 92.0 % under 1 sun irradiation, and particularly a superior self-evaporation rate of 0.49 kg m−2h−1 in the dark. More importantly, such hybrid hydrogel demonstrated excellent evaporation performance in weak sunlight and highly humid environments. This work has shed light on new insights to manufacture porous and low-enthalpy photothermal hydrogels for advanced solar-driven water treatment technology.