Hindawi Publishing Corporation International Journal of Electrochemistry Volume 2012, Article ID 675124, 20 pages doi:10.1155/2012/675124 Review Article The Use of Diamond for Energy Conversion System Applications: A Review K. I. B. Eguiluz, 1 J. M. Peralta-Hern´ andez, 2 A. Hern´ andez-Ram´ ırez, 3 J. L. Guzm ´ an-Mar, 3 L. Hinojosa-Reyes, 3 C. A. Mart´ ınez-Huitle, 4 and G. R. Salazar-Banda 1 1 Instituto de Tecnologia e Pesquisa e Programa de P´ os-Graduac ¸˜ ao em Engenharia de Processos, Universidade Tiradentes, 49032-490 Aracaju, SE, Brazil 2 Centro de Innovaci´ on Aplicada en Tecnolog´ ıas Competitivas, Departamento de Investigaci´ on Ambiental, Omega-201, Fraccionamiento Industrial Delta, 37545 Le´ on, Guanajuato, Mexico 3 Laboratorio de Fotocat´ alisis y Electroqu´ ımica Ambiental, Facultad de Ciencias Qu´ ımicas, Universidad Aut´ onoma de Nuevo Le´ on, 64570 Monterrey, NL, Mexico 4 Departamento de Qu´ ımica, Centro de Ciˆ encias Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Lagoa Nova 59078-970 Natal, RN, Brazil Correspondence should be addressed to G. R. Salazar-Banda, gianrsb@gmail.com Received 1 May 2011; Revised 20 June 2011; Accepted 21 June 2011 Academic Editor: Yasuaki Einaga Copyright © 2012 K. I. B. Eguiluz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Catalytic layers of polymer electrolyte membrane fuel cell (PEMFC) electrodes are usually composed of platinum nanoparticles dispersed on an electron conductive carbon support, which can undergo several degradation processes like dissolution of Pt and carbon corrosion under PEMFC working conditions. In this context, the major advantage of conductive boron-doped diamond (BDD) surfaces is their mechanical and chemical stability. BDD is also considered as a good substrate for studying the intrinsic properties of deposited catalysts, avoiding some problems encountered with other substrates, that is, surface corrosion, oxide formation, or electronic interactions with the deposit. Thus, the first part of this review summarized the surface modification of BDD materials, with emphasis in different techniques, to improve the catalytic efficiency of supported catalysts for PEMFCs. In addition, it is known that graphite carbon or lithium metal alloys used in advanced lithium-ion high-energy batteries suffer morphological changes during the charge-discharge cycling, which in turn results in a very poor cycle life. Thus, the use of diamond materials in these applications was also reviewed, since they have very stable surfaces and exhibits excellent electrochemical properties when compared with other carbon forms like glassy carbon and highly oriented pyrolytic graphite. 1. Introduction The continuous use of petroleum as the main source of energy has caused considerable atmospheric pollution and global warming. At the same time, with the continued climbing of crude oil price and increase of energy demand, research on alternative energy resources becomes an urgent task for scientists around the world. In that manner, elec- trochemists intensified their research in order to develop the fuel cell technology. Fuel cells can convert chemical fuels, including some renewable, directly into electricity. The main advantage of this technology over traditional energy production is that the fuel cell energy efficiency is Carnot cycle independent. Fuel cells, in particular polymer electrolyte membrane fuel cells (PEMFCs), represent an attractive technology to meet future energy needs because of their potentially high efficiency in converting stored chem- ical energy to electrical energy. However, their widespread deployment has been hampered by materials limitations, as exemplified in the catalysts by their high cost, intolerance to fuel contaminants, and degradation leading to short fuel cell lifetimes. The possible use of methanol and other small organic molecules as PEMFC fuels is promising because of their high energy density and ease of transport, compared to H 2 . The catalytic layers of PEMFC electrodes are usual- ly composed of platinum nanoparticles dispersed on an elec- tron conductive carbon support, in weight ratios higher