Advances in Chemical Engineering and Science
Vol.4 No.1(2014), Article ID:41929,13 pages DOI:10.4236/aces.2014.41004

Formation of Platinum (Pt) Nanocluster Coatings on K-OMS-2 Manganese Oxide Membranes by Reactive Spray Deposition Technique (RSDT) for Extended Stability during CO Oxidation

Hector F. Garces1, Justin Roller2,3, Cecil K. King’ondu4, Saminda Dharmarathna5, Roger A. Ristau6, Rishabh Jain2,3, Radenka Maric2,3,7, Steven L. Suib5,6

1School of Engineering, Brown University, Providence, USA

2Department of Materials Science & Engineering, University of Connecticut, Storrs, USA

3Center for Clean Energy Engineering, University of Connecticut, Storrs, USA

4Department of Sustainable Energy Science and Engineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania

5Department of Chemistry, University of Connecticut, Storrs, USA

6Institute of Materials Science, University of Connecticut, Storrs, USA

7Chemical and Biomolecular Engineering Department, University of Connecticut, Storrs, US

Email: Hector_Garces@brown.edu, Justin.roller@engr.uconn.edu, rij11002@engr.uconn.edu, kithongo@gmail.com, dasaminda@gmail.com, steven.suib@uconn.edu, raristau@ims.uconn.edu, maric@engr.uconn.edu

Received October 23, 2013; revised November 23, 2013; accepted November 30, 2013

ABSTRACT

Nanocluster formation of a metallic platinum (Pt) coating, on manganese oxide inorganic membranes impregnated with multiwall carbon nanotubes (K-OMS-2/MWCNTs), applied by reactive spray deposition technology (RSDT) is discussed. RSDT applies thin films of Pt nanoclusters on the substrate; the thickness of the film can be easily controlled. The K-OMS-2/MWCNTs fibers were enclosed by the thin film of Pt. X-ray diffraction (XRD), scanning electron microscopy/X-ray energy dispersive spectroscopy (SEM/XEDS), focus ion beam/scanning electron microscopy (FIB/SEM), transmission electron microscopy (TEM), and X-ray 3D micro-tomography (MicroXCT) which have been used to characterize the resultant Pt/K-OMS-2/MWCNTs membrane. The non-destructive characterization technique (MicroXCT) resolves the Pt layer on the upper layer of the composite membrane and also shows that the membrane is composed of sheets superimposed into stacks. The nanostructured coating on the composite membrane material has been evaluated for carbon monoxide (CO) oxidation. The functionalized Pt/K-OMS-2/MWCNTs membranes show excellent conversion (100%) of CO to CO2 at a lower temperature 200˚C compared to the uncoated K-OMS-2/MWCNTs. Moreover, the Pt/K-OMS-2/MWCNTs membranes show outstanding stability, of more than 4 days, for CO oxidation at 200˚C.

Keywords:Manganese Oxide Membrane; Pt Nanostructures; Reactive Spray Deposition Technology (RSDT); Film Deposition; X-Ray Tomography

1. Introduction

Manganese oxide K-OMS-2 is a porous mixed-valent metal oxide with applications in catalysis [1-3], environmental remediation [4], sorption processes [5], and microbial fuel cells [6]. The rationale for the synthesis of this octahedral molecular sieve (OMS) is based on its low cost, processability, stability, and excellent catalytic activity in different redox reactions [7]. Its processability permits the preparation of K-OMS-2 manganese oxide materials composed of endless-type nanofibers that can readily be assembled into a paper or membrane [8]. This versatile free-standing structure in the form of a membrane is flexible, re-dispersible, foldable, moldable, and can be modified by ion-exchange, doping, distributed over large areas for clean-up as well as being used as a supporting structure to produce composite materials. Membranes are of special interest due to their porosity, permeability, and conductivity and hence their potential uses as sensors, catalysts, and in separation processes that remove bacteria, microorganisms, particulates, and organic materi target="_blank">http://dx.doi.org/10.1016/0166-9834(91)80006-I

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  • Appendix

    Supporting Information Formation of Platinum (Pt) Nanocluster Coatings on K-OMS-2 Manganese Oxide Membranes by Reactive Spray Deposition Technique (RSDT) for Extended Stability during CO Oxidation.

    Hector F. Garces, Justin Roller, Cecil K. King’ondu, Saminda Dharmarathna, Roger A. Ristau, Rishabh Jain, Radenka Maric, Steven L. Suib*

    1) X-ray diffraction pattern of Pt nanoparticles deposited on Aluminum Stub.

    The XRD pattern of the deposited Pt nanoparticles as a

    control is presented in Figure S1 below. The pattern is obtained for the material deposited on aluminum stub during the deposition over K-OMS-2/MWCNts by RSDT.

    2) X-ray diffraction patterns of K-OMS-2, metallic Pt, and a mixture of K-OMS-2 and 2% face centered cubic Pt simulated by crystal maker.

    3) Adsorption isotherms and pore size distribution for K-OMS-2/MWCNTs membrane and Pt deposited on KOMS-2/MWCNTs.

    Figure S4. HTSEM images of coated Pt/K-OMS-2/MWCNts at 100˚C to 400˚C ramped at 50˚C·min−1 to the analysis temperature and stabilized for 30 min before obtaining the image.

    4) High Temperature Scanning Electron Microscopy (HTSEM).

    In-situ HTSEM of coated Pt/K-OMS-2/MWCNTs sample from 100˚C to 400˚C showing that the film does not suffer sintering, agglomeration, delamination or there is apparent decomposition of byproducts left after the deposition by RSDT. No depletion of the Pt particles deposited is seen.

    5) HRTEM particle size Pt deposited on K-OMS- 2/MWCNTs.