The lack of robust interphases between carbon and most metals prevent the exploration of the full scope potential of carbon-based metal matrix composites. Here, we demonstrated a scalable and straightforward way to produce strong interphase between copper (Cu) and carbon fibers (CFs) by designing a tailored titanium oxide-carbide coating (TiO y-TiC x) on CFs in a molten salt process. The oxide-carbide composition in the graded layer strongly depends on the coating temperature (800-950 ºC). A coating with a high TiO y content obtained at a low coating temperature (800 ºC) contributes to better molten-Cu wetting and strong adhesion energy between CFs and Cu during a subsequent exposure at 1200 ºC. The Cu wetting angle for the TiO y-TiC x-CF sample obtained at 800 ºC was ~80º ± 5º with a Cu surface coverage of ~50% versus ~115º and ~10% for the TiC x-CF sample made at 950 ºC. The kinetic analysis of the coating process step by step suggests a growth rate limited by the mass-transfer through the coated layer. This method provides a novel approach to improve the thermal conductivity of Cu/C composite for thermal management applications.
An ecofriendly chemical reduction of graphene oxide (GO) in water is reported. The reducing agent is an electrochemically reduced Keggin-type polyoxometalate (SiW 12 O 40 5À ). Moreover, this process leads to the fabrication of SiW 12 @rGO nanocomposite. This nanohybrid exhibits an electrochemical response which combines highf aradic and capacitive currents due to high coverage of polyoxometalates on the rGO sheets. Therefore this material has strong potentiality for energy storage.Graphene is the first two-dimensional atomic crystal available. Its singular structure is reflected by exceptionalp roperties like high mechanical strength and extremely high electrical and thermalc onductivities. The potentiala pplicationso fg raphene are multiple, ranging from electronics or flexible screens or catalysts to use in thermalm anagement. However,t he difficulties associated with its production are ac ritical drawback for largescale use. Several methods have been developedb ased on chemicala nd physical exfoliation of graphite:e lectrochemical exfoliation, [1] intercalation of elementi ng raphite compounds at elevated temperatures, [2] and liquid-phasee xfoliation using agents like N-methylpyrrolidone, iodine, chloride, or bromide. [3] Nevertheless, the most common methodf or large-scale productiono fg raphene is the moderate oxidation of graphite through the modified Hummers method, [4] followed by exfoliation of the resulting graphene oxide (GO) and its reduction to obtain graphene (reduced graphene oxide,r GO). [4][5][6] The last step involves common products like hydrazine hydrate or formaldehyde which are known to be hazardous to human health and the environment. To avoid these components, an alternative method based on the UV-assisted photoreduction of GO in the presence of polyoxometalates(POMs) and asacrificial organic reagent has been proposed. [7] POMs are ac lass of inorganic metal-oxygen cluster anions with redox properties. [8] These clusters (so-called isopoly-and heteropolyanions( HPAs)) contain highly symmetrical core assemblies of MO x units (M = V, Mo, W). They can have various structures containing for example 6, 12, or 18 metal atoms in ah igh oxidation state. For HPAs, the structure with 12 metal atoms is the Keggins tructure. In the method just mentioned the POMs act also as anionic stabilizers, preventing the aggregation of rGO and leadingt ot he formation of POM@rGO nanocomposites.H owever,o nly small amounts of rGO could be obtained under such conditions due to localized laser irradiation, and also an organic reagent has to be used. It hasa lso been shownt hat the hydrothermal reduction of GO in the presence of H 3 PMo 12 O 40 (PMo 12 )l eads to the nanocomposite PMo 12 @rGO. [9] Another route developed recently concerns the electrochemical reduction of GO assisted by POMs. [10] Herein we propose an environmentally friendly,t wo-step process for the preparation of reduced graphene oxide decorated with POMs (POM@rGO). In this process the first step is the electroreduction of SiW 12 O 40 4À (SiW 12 ...
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