10.1021/am401887g.s001 Gao Wei Gao Wei Yue-E Miao Yue-E Miao Chao Zhang Chao Zhang Zhe Yang Zhe Yang Zhenyan Liu Zhenyan Liu Weng Weei Tjiu Weng Weei Tjiu Tianxi Liu Tianxi Liu Ni-Doped Graphene/Carbon Cryogels and Their Applications As Versatile Sorbents for Water Purification American Chemical Society 2013 recycling use cryogel carbonization process RF skeletons graphene oxide gelation process metal ions NGCC hydrogel precursor bulk form Versatile Sorbents Ni nanoparticles 2013-08-14 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Ni_Doped_Graphene_Carbon_Cryogels_and_Their_Applications_As_Versatile_Sorbents_for_Water_Purification/2386858 Ni-doped graphene/carbon cryogels (NGCC) have been prepared by adding resorcinol and formaldehyde to suspension of graphene oxide (GO), using Ni<sup>2+</sup> ions as catalysts for the gelation process to substitute the usually used alkaline carbonates. The metal ions of Ni<sup>2+</sup> have elevated the cross-linking between GO and RF skeletons, thus strengthening the whole cryogel. The as-formed three-dimensional (3D) interconnected structures, which can be well-maintained after freeze-drying of the hydrogel precursor and subsequent carbonization under an inert atmosphere, exhibit good mechanical properties. During the carbonization process, Ni<sup>2+</sup> ions are converted into Ni nanoparticles and thus embedded in the interconnected structures. The unique porosity within the interconnected structures endows the cryogels with good capability for the extraction of oils and some organic solvents while the bulk form enables its recycling use. When ground into powders, they can be used as adsorbents for dyestuffs. Therefore, the as-obtained cryogels may find potential applications as versatile candidates for the removal of pollutants from water.