Recent advances in non-precious metal catalysis for oxygen-reduction reaction in polymer electrolyte fuel cells Fr ed eric Jaouen, * a Eric Proietti, a Michel Lef  evre, a R egis Chenitz, a Jean-Pol Dodelet, * a Gang Wu, b Hoon Taek Chung, b Christina Marie Johnston b and Piotr Zelenay * b Received 1st April 2010, Accepted 14th September 2010 DOI: 10.1039/c0ee00011f Hydrogen produced from water and renewable energy could fuel a large fleet of proton-exchange-fuel-cell vehicles in the future. However, the dependence on expensive Pt-based electrocatalysts in such fuel cells remains a major obstacle for a widespread deployment of this technology. One solution to overcome this predicament is to reduce the Pt content by a factor of ten by replacing the Pt-based catalysts with non-precious metal catalysts at the oxygen-reducing cathode. Fe- and Co-based electrocatalysts for this reaction have been studied for over 50 years, but they were insufficiently active for the high efficiency and power density needed for transportation fuel cells. Recently, several breakthroughs occurred that have increased the activity and durability of non-precious metal catalysts (NPMCs), which can now be regarded as potential competitors to Pt-based catalysts. This review focuses on the new synthesis methods that have led to these breakthroughs. A modeling analysis is also conducted to analyze the improvements required from NPMC-based cathodes to match the performance of Pt-based cathodes, even at high current density. While no further breakthrough in volume-specific activity of NPMCs is required, incremental improvements of the volume-specific activity and effective protonic conductivity within the fuel-cell cathode are necessary. Regarding durability, NPMCs with the best combination of durability and activity result in ca. 3 times lower fuel cell performance than the most active NPMCs at 0.80 V. Thus, major tasks will be to combine durability with higher activity, and also improve durability at cell voltages greater than 0.60 V. 1. Introduction 1.1. Future energy sources and fuels for automotive transportation Transportation accounts for about one third of the 140,000 TWh of primary energy (or 45,000 TWh of useful energy†) consumed a Institut National de la Recherche Scientifique,  Energie, Mat eriaux & T el ecommunications, 1650 Bd Lionel Boulet, Varennes, Qu ebec, J3X 1S2, Canada. E-mail: jaouen@emt.inrs.ca; Fax: +450 929 8102; Tel: +450 929 8176; dodelet@emt.inrs.ca; +450 929 8198; +450 929 8142 b Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA. E-mail: zelenay@ lanl.gov; Fax: +505 662 4292; Tel: +505 667 0197 Broader context The use of catalysts in the chemical and pharmaceutical industry is widespread. Their use in electrochemical applications is of paramount importance, especially in power sources such as batteries and fuel cells. Today, hydrogen/air polymer electrolyte fuel cells (PEFCs) are considered a promising technology to replace internal combustion engines for automotive propulsion. However, a major drawback of current PEFC technology is their high cost, in large part due to the use of platinum-based catalysts at both the anode (10%) and cathode (90%). Recently, two paths have been considered to reduce the cost of PEFCs cathode catalysts: (a) Improve the activity for oxygen reduction of Pt-based catalysts by nano-structuring or alloying, or (ii) replace Pt-based catalysts altogether with lower-cost, non-precious metal catalysts (NPMCs). This review focuses on NPMCs obtained from the heat treat- ment, at temperatures above 600  C, of carbon, nitrogen and Fe or Co precursors. The recent activity and stability breakthroughs as well as the synthesis procedures and understanding that led to these breakthroughs are summarized. The remaining improvements required for NPMCs to replace Pt-based catalysts are also highlighted. † Primary energy is the energy found in nature that has not been subjected to any conversion or transformation process, or the chemical energy contained in raw fuels. The scalar of 140,000 TWh of primary energy corresponds to 45,000 TWh of useful energy given in Schiermeier et al., Nature, 2008, 454, 816 (meaning that the average conversion efficiency from primary to useful energy is, today, 32%). 114 | Energy Environ. Sci., 2011, 4, 114–130 This journal is ª The Royal Society of Chemistry 2011 Dynamic Article Links C < Energy & Environmental Science Cite this: Energy Environ. Sci., 2011, 4, 114 www.rsc.org/ees PERSPECTIVE Downloaded by Los Alamos National Laboratory on 23 December 2010 Published on 21 December 2010 on http://pubs.rsc.org | doi:10.1039/C0EE00011F View Online