Multi-walled carbon nanotubes based Pt electrodes prepared with in situ ion exchange method for oxygen reduction

Multi-walled carbon nanotubes (MWNTs) based Pt electrodes (Pt/MWNTs) for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs) are prepared by depositing Pt nanoparticles on electrochemically functionalized MWNTs with in situ ion exchange method. The morphology of the Pt/MWNTs electrode is characterized by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The chemical composition of the electrode is analyzed by X-ray photoelectron spectroscopy (XPS). The electrochemical activity is investigated with cyclic voltammetry (CV). Pt nanoparticles are highly dispersed on MWNTs. The electrochemical surface area of the ion-exchanged electrode (prepared with ion exchange) and the conventional electrode are 688.3 and 542.6 cm2 mg−1 Pt, respectively. The Pt utilization, which is the ratio of the electrochemical surface area and the chemical surface area, is greatly enhanced on the ion-exchanged electrode (98.2%), as compared with 48.4% for the conventional one. The activity of the ion-exchanged electrode to ORR is higher than the conventional one. The increased Pt utilization and the improved electrocatalytic activity are attributed to the specific structure of the ion-exchanged electrode.