Mushroom-Like rGO/PAM Hybrid Cryogels with Efficient Solar-Heating Water Evaporation

Lacking clean water has become a matter of urgency and harvesting solar energy for water evaporation is an efficient solution. Loading photothermal materials into porous and hydrophilic matrix prominently facilitates the water evaporation efficiency. In this work, cryopolymerization was adopted first to fabricate macroporous and hydrophilic matrix–cryogel of polyacrylamide (PAM) while reduced graphene oxide (rGO) was hybridized during the fabrication with thermal reduction of graphene oxide (GO). Inspired by the transpiration of natural mushroom, the solar-heating device was integrated with the stipe of PAM cryogel, which expedited the transport of water from the water reservoir to the pileus and the elimination of heating energy loss, and the pileus composed of rGO/PAM hybrid cryogel, which enabled the high efficiency of solar light absorption and solar-heating conversion. Such a mushroom-like device achieved rapid water vapor generation and high overall efficiency of solar-heating evaporation under one-sun illumination. As well, this mushroom-like device exhibited the identical practicability of solar-heating evaporation for the different water sources such as the wastewater containing salt, surfactant, or oil, compared with pure water. Within 10 cycles, those mushroom-like rGO/PAM hybrid cryogels retained the analogous solar-heating evaporation performance. The mushroom bioinspiration and cryopolymerization would afford a novel and convenient route for highly efficient solar-heating water evaporation.