Experimental Measurements on the Thermal Conductivity of Glycerol-Based Nanofluids with Different Thermal Contrasts

We report, in this work, our study of the thermal conductivity of high-viscosity nanofluids based on glycerol. Three nanofluids have been prepared with different thermal contrasts, by suspending graphene flakes, copper oxides, or silica nanoparticles in pure glycerol. The nanofluids were thermally characterized at room temperature with the 3ω technique, with low amplitudes of the temperature oscillations. A significant enhancement of the thermal conductivity is found in both the glycerol/copper oxide and the glycerol/graphene flake nanofluids. Our results question the role played by the Brownian motion in the microscopic mechanisms of the thermal conductivity of high-viscosity glycerol-based nanofluids. A similar behavior of the thermal conductivity as a function of the nanoparticle volume fraction was found for all three glycerol-based nanofluids presently investigated. These results could be explained on the basis of fractal aggregation in the nanofluids.

Crumpled Graphene-Storage Media for Hydrogen and Metal Nanoclusters

Understanding the structural behavior of graphene flake, which is the structural unit of bulk crumpled graphene, is of high importance, especially when it is in contact with the other types of atoms. In the present work, crumpled graphene is considered as storage media for two types of nanoclusters—nickel and hydrogen. Crumpled graphene consists of crumpled graphene flakes bonded by weak van der Waals forces and can be considered an excellent container for different atoms. Molecular dynamics simulation is used to study the behavior of the graphene flake filled with the nickel nanocluster or hydrogen molecules. The simulation results reveal that graphene flake can be considered a perfect container for metal nanocluster since graphene can easily cover it. Hydrogen molecules can be stored on graphene flake at 77 K, however, the amount of hydrogen is low. Thus, additional treatment is required to increase the amount of stored hydrogen. Remarkably, the size dependence of the structural behavior of the graphene flake filled with both nickel and hydrogen atoms is found. The size of the filling cluster should be chosen in comparison with the specific surface area of graphene flake.

Effect of Graphene Flake Size on Functionalisation: Quantifying Reaction Extent and Imaging Locus with Single Pt atom Tags

Here, the locus of functionalisation on graphene-related materials and the progress of the reaction is shown to depend strongly on the starting feedstock. Five characteristically different graphite sources were exfoliated...

Atomistic Explorations of Mechanisms Dictating the Shear Thinning Behavior and 3D Printability of Graphene Flake Infused Epoxy Inks

Nanofiller-based epoxy inks have found extensive use in fabricating 3D printed nanocomposites for applications in aerospace, automobile, and marine systems. Here we employ an all-atom molecular dynamic (MD) simulation to...

Mechanosensing of a Graphene Flake on a Bent Beam

The ability of mechanosensing is essential for intelligent systems. Here we show by molecular dynamics (MD) simulations that a graphene flake on a bent beam exhibits amazing mechanosensing behavior, termed flexotaxis. The graphene flake can perceive the beam bending gradient which indeed leads to a gradient of atomic density that produces a driving force on the flake toward the direction of increasing density. An analytical model is developed to further confirm the mechanism, and the simulation results can be well reproduced by the model. Our findings may have general implications not only for the potential applications of graphene as sensing elements in nanoscale intelligent devices but also for the exploration of mechanosensing capability of other two-dimensional materials.