Special Issue "Carbon Catalysts"

Guest Editor
Prof. Dr. Seong-Ho Yoon
Institute for Materials Chemistry and Engineering, Kyushu University 6-1 Kasuga Koen, Kasuga, Fukuoka 816-8580, Japan
Website: http://carbon.cm.kyushu-u.ac.jp/index.htm
E-Mail: yoon@cm.kyushu-u.ac.jp

Guest Editor
Prof. Dr. Elena Pastor
Dpto. Química Física, Facultad de Química, Universidad de La Laguna, C/Astrofísico Francisco Sánchez s/n. E-38071. La Laguna. Tenerife, Spain
Website: http://www.euchems.eu/index.php?id=376&no_cache=1&tx_wfqbe_pi1% 5Bdetailsid%5D=806
E-Mail: epastor@ull.es
Interests: electrocatalysis and carbon supported catalysts for applications in electrochemical devices

Guest Editor
Dr. Maria Jesús Lázaro
Institute of Carbochemistry, CSIC-Spanish National Research Council, C/. Miguel Luesma Castán, 4, 50018 Zaragoza, Spain
E-Mail: mlazaro@icb.csic.es
Interests: carbon materials; catalyts; fuel cell; hydrogen; carbon catalysts; NO Reduction

Dear Colleagues,

Carbon catalysts have been used over the last decades for the utilization in several processes. Carbon catalysts consists of metals or metallic compounds supported on carbon materials which role is not only to maintain the catalytic phase in a well dispersed state but also affect the catalytic activity, by means of direct participation in nay of the steps of the reaction mechanism, or by favouring the interaction between active phase and support.

Carbon materials fulfil the properties desirable in a catalyst support such as inertness, towards unwanted reaction, stability, mechanical properties, surface area and porosity, the possibility of being manufacture in different physical form.

This special issue invites significant contributions of different applications of carbon catalyst such as in electrochemical devices, reduction of emissions, in the production of valuable products and in other applications.

Prof. Dr. Seong-Ho Yoon
Prof. Dr. Elena Pastor
Dr. Maria Jesús Lázaro
Guest Editors

Submission

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed Open Access quarterly journal published by MDPI.

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Type of Paper: Article
Title: Nanostructured Carbon Materials as Supports in the Preparation of PEM Fuel Cell Electrocatalysts
Authors: M.E. Gálvez, L. Calvillo, C. Alegre, D. Sebastián, I. Suelves, S. Pérez-Rodríguez, V. Celorrio, E. Pastor, R. Moliner and M.J. Lázaro
Affiliations: Instituto de Carboquímica,CSIC, C/Miguel Luesma Castán 4, 50018 Zaragoza, Spain; E-Mail: mlazaro@icb.csic.es
Abstract: Among the different types of fuel cells, polymer electrolyte fuel cells (PEMFCs and DAFCs) are the most promising for both portable and automotive applications due to their advantageous features such as high power density at low temperature, low weight, compactness, and suitability for discontinuous operation. At present, the most effective fuel cell catalysts consist on highly dispersed platinum-based nanoparticles. The high cost of noble metals used as electrode catalysts is one of the significant obstacles for the commercialization of PEMFCs. Therefore, the metal nanoparticles are normally supported on carbon materials in order to maximize their surface area and decrease the total amount of metal employed. Thus, the fraction of metal particles exposed to the reactants increases, improving the catalyst utilization. Among other factors, the performance of metal nanoparticles supported on carbon materials depends strongly on the properties of the support. Different advanced nanostructured carbon materials, such as carbon nanocoils, carbon nanofibers, graphitized ordered mesoporous carbons and carbon xerogels, presenting interesting features such as high electrical conductivity and extensively developed porous structure were synthesized and used as supports in the preparation of electrocatalysts for direct methanol fuel cells (DMFCs). The main advantage of these supports is that their physical properties and surface chemistry can be tailored to adapt the carbonaceous material to the catalytic requirements. Moreover, all of them present a highly mesoporous structure, diminishing diffusion problems, and both graphitic character and surface area can be conveniently modified. In the present work, the influence of the particular features of each material on the catalytic activity and stability was analyzed. Results have been compared with those obtained for commercial catalysts supported on Vulcan XC-72R, Pt/C and PtRu/C (ETEK). Both a highly ordered graphitic and mesopore-enriched structure of these advanced nanostructured materials resulted in an improved electrochemical performance in comparison to the commercial catalysts assayed, both towards CO and alcohol oxidation.

Type of Paper: Article
Title: Surface Termination Effects of HPHT Diamond Powder Support on the Electrocatalytic Reactivity of Metal Nanoparticles
Authors: J.J.L. Humphrey^†, D. Plana^†, V. Celorrio^† and D.J. Fermín^†*
Affiliation: School of Chemistry, University of Bristol, Cantocks Close, Bristol, BS8 1TS, UK
Abstract: Studying the effect of support surface groups and charges on the catalytic reactivity of metal nanoparticles is a complex process. Herein high-pressure, high-temperature (HPHT) nanodiamond powders were used as model support surfaces for Au-Pd core-shell nanostructures for the electrochemical oxidation of CO, formic acid and ethanol in order to study the effect of support surface groups on catalytic reactivity. Pre-synthesised core-shells were incorporated onto Hydrogen- or Oxygen-terminated HPHT diamond powders, ensuring differences observed were due to changes in the surface chemistry and dipole moment. CO stripping voltammetry experiments showed unusual behaviour on oxygen terminated supports, with more than one potential cycle required to remove adsorbed CO from the surface of the catalyst. This phenomenon was reflected in differing reactivity in all oxidation reactions studied, with hydrogen-terminated supports always exhibiting higher current densities. These effects proved particularly sensitive to pH, which in turn affects the surface charge of the diamond particles.

Type of Paper: Article
Title: Catalysts supported on carbon materials for the selective hydrogenation of citral
Authors: Esther Bailón-García, Francisco J. Maldonado-Hódar, Agustín F. Pérez-Cadenas and Francisco Carrasco-Marín
Affiliation: Carbon Materials Research Group, Department of Inorganic Chemistry, Faculty of Sciences, University of Granada. Campus Fuentenueva s/n, 18071 Granada, Spain; E-mail address: estherbg@ugr.es.
Abstract: The heterogeneously catalyzed selective-hydrogenation of citral is one of the more feasible ways for obtaining its appreciated unsaturated-alcohols, nerol and geraniol, which are present in over 250 essential oils. Thus, citral has very recently come to be produced petro-chemically in very large quantities, and so partial hydrogenation of citral has become a very economical route for the production of these compounds. But the selective hydrogenation of citral is not easy, because citral in an a,b unsaturated aldehyde which possesses three double bonds that can be hydrogenated: an isolated C=C bond and the conjugated C=O and C=C bonds. For this reason, in the adequate catalysts selection there are several important issues, which affect on the product selectivity: the active metal, average metal-particle size, (factors as catalyst preparation method, catalyst precursor, surface area, which affect the metal-particle size), porosity, the addition of a second catalytic metal, and of course the type of catalyst support: carbon materials are a very interesting supports for this type of hydrogenation reaction due to their unique chemical and textural properties. This review collects and analyzes the results obtained in the selective hydrogenation of citral catalyzed by carbon materials supported metals.