ORIGINAL PAPER Electrocatalytic oxygen reduction on single-walled carbon nanotubes supported Pt alloys nanoparticles in acidic and alkaline conditions Ahmad Nozad Golikand Æ Mehdi Asgari Æ Elaheh Lohrasbi Æ Mohammad Yari Received: 22 October 2008 / Accepted: 26 January 2009 / Published online: 20 February 2009 Ó Springer Science+Business Media B.V. 2009 Abstract The objective of this study is to improve the catalytic activity of platinum by alloying with transition metal (Pd) in gas diffusion electrodes (GDEs) by oxygen reduction reaction (ORR) at cathode site and comparison of the acidic and alkaline electrolytes. The high porosity of single-walled carbon nanotubes (SWCNTs) facilitates dif- fusion of the reactant and facilitates interaction with the Pt surface. It is also evident that SWCNTs enhance the sta- bility of the electrocatalyst. Functionalized SWCNTs are used as a means to facilitate the uniform deposition of Pt on the SWCNT surface. The structure of SWCNTs is nearly perfect, even after functionalization, while other types of CNTs contain a significant concentration of structural defects in their walls. So catalysts supported on SWCNTs are studied in this research. The electrocatalytic properties of ORR were evaluated by cyclic voltammetry, polarization experiments, and chronoamperometry. The morphology and elemental composition of Pt alloys were characterized by X-ray dif- fraction (XRD) analysis and inductively coupled plasma atomic emission spectroscopy (ICP-AES) system. The catalytic activities of the bimetallic catalysts in GDEs have been shown to be not only dependent on the composition, but also on the nature of the electrolytes. The GDEs have shown a transition from the slow ORR kinetics in alkaline electrolyte to the fast ORR kinetics in the acidic electro- lyte. The results also show that introduction of Pd as transition metal in the Pt alloys provides fast ORR kinetics in both acidic and alkaline electrolytes. The performance of GDEs with Pt–Pd alloy surfaces towards the ORR as a function of the alloy’s overall composition and their behavior in acidic electrolyte was also studied. These results show that the alloy’s overall composition and also the nature of the electrolytes have a large effect on the performance of GDEs for ORR. Keywords Platinum  Alloy  Oxygen reduction reaction  Gas diffusion electrode  Alkaline electrolyte  Acid electrolyte  Carbon nanotubes 1 Introduction Electrochemical reduction of oxygen (O 2 ) plays a signifi- cant role in fuel cells, gas sensors, and electrosynthesis of hydrogen peroxide. It has been a pivotal subject for extensive studies in view of its importance in fuel-cell applications, and in the detection of oxygen levels in areas such as biochemistry, neuroscience, and physiology [1–5]. This has been increasing interest to develop economic and robust alternatives as electrocatalysts for the ORR [6– 10]. Most of the basic studies on oxygen reduction reaction (ORR) have been conducted in acidic electrolyte [8–10]. A few ORR studies in alkaline solutions have also been reported [11–15]. The situation in alkaline electrolyte is different from that in acid electrolyte. Alkaline electrolytes present many opportunities for non-Pt catalysts for the ORR. Materials that have little or no measurable activity for the ORR in acid have substantial level of activity in alkaline solution. The first technological alkaline fuel cell, A. N. Golikand (&)  M. Asgari Chemistry Department, NSTRI, Tehran, Iran e-mail: ahmadnozadgolikand@yahoo.com A. N. Golikand  E. Lohrasbi Corrosion Lab., Material School, NSTRI, Tehran, Iran M. Yari Chemistry Department, Shahre Ghods Branch, Islamic Azad University, Shahre Ghods, Iran 123 J Appl Electrochem (2009) 39:1369–1377 DOI 10.1007/s10800-009-9812-7