Activation of gold decorated carbon nanotube hybrids for targeted gas adsorption and enhanced catalytic oxidation

Abstract

10Free standing assemblies of carbon nanotubes (CNTs), known as bucky-paper, (BP) have been functionalised through the in-situ plating of gold nanoparticles within the interstitial spaces in the BP. The nanoparticles are extremely small and well distributed at short plating times, so much so that the specific surface area of the BP is actually 15 increased by the gold incorporation. These well distributed nanoparticles exhibit high enthalpy hydrogen storage and selective carbon dioxide adsorption over other gases, in particular methane. In concert with the conductive BP substrate, it has been demonstrated that these materials can also act as high turnover heterogeneous catalysts. (Graphical abstract)Keywords 25 gold decorated carbon nanotube; composite bucky-paper; specific gas storage; catalytic activity Self-supporting BPs were processed from chemical vapour deposition grown multi walled CNTs as described in a previous study 51 . Research highlightsIn short, the functionalized CNTs were then suspended in propan-2-ol by 5 repeated cycles of freezing at -17 ºC followed by bath sonication as per the method developed in 50 . The CNT suspension was then filtered on top 10 of a porous poly(ether sulphone) membrane to form a self-supporting BP.BPs were exposed for 10 min to a flow of UV induced ozone in order to form hydroxyl groups at the surface of outer CNT walls 52, 53 . These groups are needed to both facilitate wetting of the CNTs by the plating solutions and as anchors for the initial plating reactions. 15The procedure of electroless gold deposition within porous materials has been described by Martin et al. 54 and was previously used to fabricate pure gold nanotubes 48 in a three step protocol. During the first step, BP properties analysisThe gold content in the structure was determined by Thermo Scanning Electron Micrographs (SEM) at 5 keV, 52 º of tilt and 5 cm working distance. The Gallium (Ga) milling was performed with an initial beam current of 7 nA followed by cleaning steps at 0.1 nA. Eventually, pore size distribution was determined by perm-porometry on a capillary flow porometer from Porous Materials Inc. in wet-up/dry-up mode. 50Galwick and N2 were respectively used as the wetting liquid and to pressurize the BP pores up to 500 psi. Gas adsorptionThe adsorption of N2, CH4 and CO2 was performed at room Catalytic activity determinationBPs were exposed to pure analytical grade pentanal at 70 ºC in oxygenated CDCl3 for times of either 2 or 24 h. The composition of the solution before and after being exposed to the catalytic influence of the 65 BPs were analysed using Nuclear Magnetic Resonance (NMR) on aBruker 400 MHz spectrometer. TGA performed on the series of samples showed an initial diminished thermal stability which was attributed to the ozone treatment inducing defects on the CNT walls. However, after 10 h of plating the 90 stability, compared to a non treated sample, was recovered and improved. C. Results and DiscussionThe samples were all stable up to 400 ºC. The gold content c...

The fabrication and surface functionalization of porous metal frameworks – a review

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Fabrication of thin film composite poly(amide)-carbon-nanotube supported membranes for enhanced performance in osmotically driven desalination systems

“…PSI and the pore size distribution was determined following a procedure previously detailed in [50].…”

Commercial steel wool for reduction of hexavalent chromium in wastewater: batch kinetic studies and rate model

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