Janus structured carbon-graphene composite aerogel for high efficiency solar water evaporation

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Solar-Driven Interfacial Evaporation (SIE) represents a promising technology for seawater desalination owing to its sustainable and non-polluting characteristics. One of the key issues for the SIE technology in practical application is the high evaporation rate of SIE materials. Carbon-based materials are one of the most promising SIE materials because of their broad solar spectrum absorption capability, high stability and low cost. However, few carbon-based SIE materials can achieve a high evaporation rate beyond 3.6 kg·m−2·h−1. Here, we propose a straightforward synthesis strategy for a three-dimensional and self-floating Janus structured carbon-graphene composite aerogel (CrGOA) evaporator with an ultrahigh water evaporation rate. The CrGOA is derived from a chitosan-furfural-graphene oxide (GO) hybrid aerogel by a one-pot method, which consists of a dual chemical reaction and a combined precipitation and freeze-casting process. The CrGOA exhibits a unique hierarchical porous structure that alters the evaporation behavior of the water molecules, and significantly reduced the enthalpy of evaporation. Under 1 sun illumination, the CrGOA achieve an ultrahigh evaporation rate of 3.66 kg·m−2·h−1 and a steam generation efficiency of 96.9 % in pure water, and a high evaporation rate of 2.95 kg·m−2·h−1 in 16 wt% brine without any salt scaling. Moreover, the CrGOA exhibits rapid photothermal responsiveness under low light and self-cleaning salt dissolving properties. This work provides a promising option for the development of efficient, stable, and salt-resistant SIE materials.