Aerogels Based on MXene Nanosheet/Reduced Graphene Oxide Composites with Vertically Aligned Channel Structures for Solar-Driven Vapor Generation

We fabricate MXene-reduced graphene oxide (rGO) hybrid aerogels with vertically aligned channel structures, where the framework of three-dimensional (3D) structures consists of MXene, and rGO nanosheets are attached to the MXene framework. MXene–rGO hybrid aerogels exhibit extremely high light absorption and excellent hydrophilicity, which facilitate vapor generation by harvesting solar energy. Moreover, vertically aligned channel structures dramatically enhance the water transport inside porous light absorbers and substantially reduce the light reflection loss and the heat loss due to multiple internal reflections. Meanwhile, the functional polar groups in the aerogels alter the states of water molecules because the water molecules have strong interactions with the functional polar groups. The coexistence of multiple water states (bound water, intermediate water, and free water) gives rise to the reduction of the vaporization enthalpy and fast water evaporation. The MXene–rGO hybrid aerogels achieve a water evaporation rate of 2.84 kg m–2 h–1 under 1 sun irradiation. The energy transfer efficiency is 96%. We also use the MXene–rGO hybrid aerogels to desalinate the seawater, and desalinated seawater meets the requirements for drinking water.