Palladium Nanostructures Synthesis by Sputtering Deposition on HOPG Surfaces L. Arroyo-Ramírez a,b,c , Y. Figueroa d , D. Rodríguez d , W. Otaño b,c,d , and C. R. Cabrera* a,b,c a Department of Chemistry, University of Puerto Rico, San Juan, PR 00936-8377 b Center for Advanced Nanoscale Materials, University of Puerto Rico, San Juan, PR 00936-8377 c Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00931 d Department of Physics-Mathematics, University of Puerto Rico, Cayey, PR 00736 *Corresponding author, Email: carlos.cabrera2@upr.edu The synthesis of palladium thin films and shell nanostructures by dc-magnetron sputtering deposition on highly ordered pyrolytic graphite (HOPG) surfaces is described. Electrospun polymer fibers mats were used as templates for the Pd shell nanostructures formation. The morphology was characterized with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Pd nanostructures were used as catalysts for oxygen reduction reaction (ORR). The ORR activity was evaluated in sulfuric acid and the methanol tolerance in 1 M methanol solutions saturated with oxygen. The Pd shell nanostructures have better ORR activity than Pd thin films. Introduction Cathode electrodes, for direct methanol fuel cells (DMFC), have the problem of requiring high cost catalysts and its degradation due to methanol crossover (1,2). Moreover, the deposition methods for the catalysts are complex and time consuming. To solve this drawback it is necessary to find a catalyst with high methanol tolerance and simple methodology for its deposition. Sputtering is a technique that allows easy modification of different substrates with a great variety of materials and high degree of control of their properties (3). The sputter process reduces electrode preparation time compared to conventional method (paste method). Electrospinning is a simple process to produce fibers from polymer solutions due to electrostatic forces (4). Sputtering allows the metal deposition on top of these fibers to produce nanostructures. It is known that palladium and Pd-based alloys have resulted in extremely active catalysts for the oxygen reduction reaction (ORR) with high methanol tolerance (5,6). Our focus is on the use of the sputtering method for the synthesis of catalytic nanostructures on highly ordered pyrolytic graphite (HOPG) surfaces as model to be used for fuel cell applications. In this work, we synthesized palladium thin films and shell nanostructures by sputtering deposition. The Pd nanostructures were characterized by cyclic and linear sweep voltammetry, atomic force microscopy (AFM) and scanning electron microscopy (SEM). ECS Transactions, 28 (7) 1-7 (2010) 10.1149/1.3491767 ©The Electrochemical Society 1 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 54.242.211.116 Downloaded on 2016-06-06 to IP