TY - JOUR A1 - Meyer-Plath, Asmus A1 - Beckert, F A1 - Tölle, FJ A1 - Sturm, Heinz A1 - Mülhaupt, R T1 - Stable aqueous dispersions of functionalized multi-layer graphene by pulsed underwater plasma exfoliation of graphite N2 - A process was developed for graphite particle exfoliation in water to stably dispersed multi-layer graphene. It uses electrohydraulic shockwaves and the functionalizing effect of solution plasma discharges in water. The discharges were excited by 100 ns high voltage pulsing of graphite particle chains that bridge an electrode gap. The underwater discharges allow simultaneous exfoliation and chemical functionalization of graphite particles to partially oxidized multi-layer graphene. Exfoliation is caused by shockwaves that result from rapid evaporation of carbon and water to plasma-excited gas species. Depending on discharge energy and locus of ignition, the shockwaves cause stirring, erosion, exfoliation and/or expansion of graphite flakes. The process was optimized to produce long-term stable aqueous dispersions of multi-layer graphene from graphite in a single process step without requiring addition of intercalants, surfactants, binders or special solvents. A setup was developed that allows continuous production of aqueous dispersions of flake size-selected multi-layer graphenes. Due to the well-preserved sp(2)-carbon structure, thin films made from the dispersed graphene exhibited high electrical conductivity. Underwater plasma discharge processing exhibits high innovation potential for morphological and chemical modifications of carbonaceous materials and surfaces, especially for the generation of stable dispersions of two-dimensional, layered materials. KW - Exfoliation KW - Graphene KW - Aqueous dispersion KW - Solution plasma KW - Functionalization KW - Electrohydraulic effect KW - Shear exfoliation KW - Oxide-films KW - Water PY - 2016 U6 - https://doi.org/10.1088/0022-3727/49/4/045301 SN - 0022-3727 VL - 49 IS - 4 SP - 045301-1 EP - 045301-11 AN - OPUS4-35796 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -