http://users.encs.concordia.ca/~mojtaba/elec6271/silver%20nanoparticles.pdf

Silver nanoparticles: green synthesis and their antimicrobial activities.

Rod Borup is a Team Leader in the fuel cell program at Los Alamos National Lab in Los Alamos, New Mexico. He received his B.S.E. in Chemical Engineering from the University of Iowa in 1988 and his Ph.D. from the University of Washington in 1993. He has worked on fuel cell technology since 1994, working in the areas of hydrogen production and PEM fuel cell stack components. He has been awarded 12 U.S. patents, authored over 40 papers related to fuel cell technology, and presented over 50 oral papers at national meetings. His current main research area is related to water transport in PEM fuel cells and PEM fuel cell durability. Recently, he was awarded the 2005 DOE Hydrogen Program R&D Award for the most significant R&D contribution of the year for his team's work in fuel cell durability and was the Principal Investigator for the 2004 Fuel Cell Seminar (San Antonio, TX, USA) Best Poster Award. Jeremy Meyers is an Assistant Professor of materials science and engineering and mechanical engineering at the University of Texas at Austin, where his research focuses on the development of electrochemical energy systems and materials. Prior to joining the faculty at Texas, Jeremy workedmore » as manager of the advanced transportation technology group at UTC Power, where he was responsible for developing new system designs and components for automotive PEM fuel cell power plants. While at UTC Power, Jeremy led several customer development projects and a DOE-sponsored investigation into novel catalysts and membranes for PEM fuel cells. Jeremy has coauthored several papers on key mechanisms of fuel cell degradation and is a co-inventor of several patents. In 2006, Jeremy and several colleagues received the George Mead Medal, UTC's highest award for engineering achievement, and he served as the co-chair of the Gordon Research Conference on fuel cells. Jeremy received his Ph.D. in Chemical Engineering from the University of California at Berkeley and holds a Bachelor's Degree in Chemical Engineering from Stanford University. Bryan Pivovar received his B.S. in Chemical Engineering from the University of Wisconsin in 1994. He completed his Ph.D. in Chemical Engineering at the University of Minnesota in 2000 under the direction of Profs. Ed Cussler and Bill Smyrl, studying transport properties in fuel cell electrolytes. He continued working in the area of polymer electrolyte fuel cells at Los Alamos National Laboratory as a post-doc (2000-2001), as a technical staff member (2001-2005), and in his current position as a team leader (2005-present). In this time, Bryan's research has expanded to include further aspects of fuel cell operation, including electrodes, subfreezing effects, alternative polymers, hydroxide conductors, fuel cell interfaces, impurities, water transport, and high-temperature membranes. Bryan has served at various levels in national and international conferences and workshops, including organizing a DOE sponsored workshop on freezing effects in fuel cells and an ARO sponsored workshop on alkaline membrane fuel cells, and he was co-chair of the 2007 Gordon Research Conference on Fuel Cells. Minoru Inaba is a Professor at the Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, Japan. He received his B.Sc. from the Faculty of Engineering, Kyoto University, in 1984 and his M.Sc. in 1986 and his Dr. Eng. in 1995 from the Graduate School of Engineering, Kyoto University. He has worked on electrochemical energy conversion systems including fuel cells and lithium-ion batteries at Kyoto University (1992-2002) and at Doshisha University (2002-present). His primary research interest is the durability of polymer electrolyte fuel cells (PEFCs), in particular, membrane degradation, and he has been involved in NEDO R&D research projects on PEFC durability since 2001. He has authored over 140 technical papers and 30 review articles. Kenichiro Ota is a Professor of the Chemical Energy Laboratory at the Graduate School of Engineering, Yokohama National University, Japan. He received his B.S.E. in Applied Chemistry from the University of Tokyo in 1968 and his Ph.D. from the University of Tokyo in 1973. He has worked on hydrogen energy and fuel cells since 1974, working on materials science for fuel cells and water electrolysis. He has published more than 150 original papers, 70 review papers, and 50 scientific books. He is now the president of the Hydrogen Energy Systems Society of Japan, the chairman of the Fuel Cell Research Group of the Electrochemical Society of Japan, and the chairman of the National Committee for the Standardization of the Stationary Fuel Cells. ABSTRACT TRUNCATED« less

Scientific aspects of polymer electrolyte fuel cell durability and degradation.

This review analyses the literature from the early 1990s until the beginning of 2003 and covers the use of carbon nanotubes (CNT) and nanofibers as catalysts and catalysts supports. The article is composed of three sections, the first one explains why these materials can be suitable for these applications, the second describes the different preparation methods for supporting metallic catalysts on these supports, and the last one details the catalytic results obtained with nanotubes or nanofibers based catalysts. When possible, the results were compared to those obtained on classical carbonaceous supports and explanations are proposed to clarify the different behaviors observed.

Carbon nanotubes and nanofibers in catalysis

A review of anode catalysis in the direct methanol fuel cell

Multiwalled carbon nanotube-supported Pt (Pt/MWNT) nanocomposites were prepared by both the aqueous solution reduction of a Pt salt (HCHO reduction) and the reduction of a Pt ion salt in ethylene glycol solution. For comparison, a Pt/XC-72 nanocomposite was also prepared by the EG method. The Pt/MWNT catalyst prepared by the EG method has a high and homogeneous dispersion of spherical Pt metal particles with a narrow particle-size distribution. TEM images show that the Pt particle size is in the range of 2-5 nm with a peak at 2.6 nm, which is consistent with 2.5 nm obtained from the XRD broadening calculation. Surface chemical modifications of MWNTs and water content in EG solvent are found to be the key factors in depositing Pt particles on MWNTs. In the case of the direct methanol fuel cell (DMFC) test, the Pt/MWNT catalyst prepared by EG reduction is slightly superior to the catalyst prepared by aqueous reduction and displays significantly higher performance than the Pt/XC-72 catalyst. These differences in catalytic performance between the MWNT-supported or the carbon black XC-72-supported catalysts are attributed to a greater dispersion of the supported Pt particles when the EG method is used, in contrast to aqueous HCHO reduction and to possible unique structural and higher electrical properties when contrasting MWNTs to carbon black XC-72 as a support.

Preparation and Characterization of Multiwalled Carbon Nanotube-Supported Platinum for Cathode Catalysts of Direct Methanol Fuel Cells

Multistep deposition and reactive decomposition of a precursor molecule containing one Pt and one Ru atom on herringbone graphitic carbon nanofibers (GCNFs) affords a Pt−Ru/GCNF nanocomposite containing Pt−Ru alloy nanoclusters widely dispersed on the GCNF support. The nanocomposite has a total metal content of 42 wt % with a bulk Pt/Ru atomic ratio of ca. 1:1, and metal alloy nanoclusters having average particle sizes of 6 nm as calculated from XRD peak widths or 7 nm as measured directly from TEM images. XRD and electrochemical analysis of the nanocomposite as-prepared and stored under ambient conditions reveals the presence of small amounts of Ru metal and oxidized metal species. Comparative testing of this nanocomposite and an unsupported Pt−Ru colloid of similar surface area and catalyst particle size as anode catalysts in a working direct-methanol fuel cell (DMFC) reveals a 50% increase in performance for the Pt−Ru/GCNF nanocomposite. More detailed study of the catalytic performance of metal alloy/G...

A Pt−Ru/Graphitic Carbon Nanofiber Nanocomposite Exhibiting High Relative Performance as a Direct-Methanol Fuel Cell Anode Catalyst

Six Pt−Ru/carbon fiber nanocomposites have been prepared by using a bimetallic precursor as a source of metal. Carbon fiber supports include singled-walled nanotubes, multiwalled nanotubes, or graphitic carbon nanofibers having either platelet, wide herringbone, or narrow tubular herringbone atomic structures. Preparative procedures have been optimized to enhance the performance of these nanocomposites as anode electrocatalysts in direct methanol fuel cells. Pt−Ru nanoparticles are the major metal-containing component of these nanocomposites along with variable amounts of Ru metal. A range of direct methanol fuel cell performance is observed with a Pt−Ru/narrow tubular herringbone graphitic carbon nanofiber nanocomposite showing the highest performance. This performance is equivalent to that recorded for an unsupported Pt−Ru colloid at an anode catalyst loading of 2.7 mg total metal/cm2, but 64% greater than that of the unsupported Pt−Ru colloid at a lower catalyst loading of 1.5 mg/cm2.

Pt−Ru/Carbon Fiber Nanocomposites: Synthesis, Characterization, and Performance as Anode Catalysts of Direct Methanol Fuel Cells. A Search for Exceptional Performance

Pt—Ru/Carbon Fiber Nanocomposites: Synthesis Characterization, and Performance as Anode Catalysts of Direct Methanol Fuel Cells. A Search for Exceptional Performance.

Thin films able to sustain an efficient photoreduction of Ag+ ions with 350 nm photons in air were prepared by crosslinking poly(vinyl alcohol) with glutaraldehyde in the presence of poly(acrylic acid). Standard colloid techniques served as screening methods for the selection of polymer compositions yielding films with desired properties. When present at high concentrations, Ag+ ions were reduced at room temperature in the films by poly(vinyl alcohol) but poly(acrylic acid) inhibited the slow dark reaction. Optical signals with maxima above 400 nm resulted from both reduction processes. The available evidence confirmed that they originated from nanometer-sized metal particles and is inconsistent with results for other proposed chromophores. An additional absorption centered at 280 nm that formed only under illumination was assigned to Ag3+ clusters. Small Ag crystallites with similar size distributions and with an average diameter of 5 nm were the main product of the photoreduction in non-crosslinked or c...

Light-Induced Formation of Silver Particles and Clusters in Crosslinked PVA/PAA Films

Graphitic carbon nanofibers (GCNFs) are prepared from CO/H2 with a nickel-rich Fe-Ni (2:8) growth catalyst supported on three different water-soluble supports (Na4SiO4, Na2SiO3, and Na2CO3). GCNF products are formed with yield and crystallinity comparable to those of GCNF product produced with the same growth catalyst supported on fumed silica. Separation of GCNF product from the solid support is accomplished by aqueous dissolution of the support. This synthetic method extends the convenient isolation of GCNFs formed with supported growth catalysts to a wide variety of potential solid supports.

Eve S. Steigerwalt

Papers

A Pt−Ru/Graphitic Carbon Nanofiber Nanocomposite Exhibiting High Relative Performance as a Direct-Methanol Fuel Cell Anode Catalyst

Pt−Ru/Carbon Fiber Nanocomposites: Synthesis, Characterization, and Performance as Anode Catalysts of Direct Methanol Fuel Cells. A Search for Exceptional Performance

Pt—Ru/Carbon Fiber Nanocomposites: Synthesis Characterization, and Performance as Anode Catalysts of Direct Methanol Fuel Cells. A Search for Exceptional Performance.

Light-Induced Formation of Silver Particles and Clusters in Crosslinked PVA/PAA Films

Preparation of graphitic carbon nanofibers with the use of water-soluble supports.