Effect of Carbon Support on the Properties of Electrochemically Deposited Platinum and Polyaniline

Abstract

Carbon has unique and desirable properties for use in applications such as fuel cells and batteries. The properties can vary widely depending on its structure and surface characteristics. Two types of carbon, a synthetic graphite produced from petroleum coke and an extruded graphite rod, were characterized using Raman spectroscopy and X-ray Photoelectron spectroscopy and the features were correlated with electrochemical properties of the material. The graphite rod was found to have a more disordered structure, greater sp 3 character, and a greater surface oxygen content as compared to the synthetic graphite from coke. Our results show that the characteristics of electrodeposited platinum and polyaniline depend on the type of substrate; the preferable carbon for producing composite materials for catalyst applications is the graphite from petroleum coke. © The Author Carbon used as a support material in fuel cells and batteries can vary in properties depending on the structure and impurities present. Reviews on carbon supports have indicated that graphite is commonly chosen to support catalytic metals due to its inert character and conductivity, and the support itself can affect performance of the fuel cell. [1][2][3][4] Composite electrodes can be produced from potentiostatic depositions of platinum and/or polyaniline (PANI) directly onto the carbon surface. Carbon supported platinum (C/Pt) is widely used for its known activity toward alcohol oxidation, 5-7 and carbon supported PANI (C/PANI), or even carbon-platinum supported PANI (C/Pt-PANI) electrodes are also attractive for the fabrication of composite catalyst materials. 8,9 Previous studies have shown that PANI can be used as a viable matrix for the insertion of catalytically active atomic-sized metal clusters, using platinum as support.10-12 We have focused our recent studies on using carbon as a support due to its benefits of being conductive, lightweight and inexpensive.13 However, in order to choose the appropriate carbon for a support electrode, understanding the effects that the substrate has on the PANI film is necessary. Dinh and Birss have compared the effects of differing types of support materials, such as noble metals and glassy carbon, on PANI properties. Impedance and CV studies on PANI grown by cycling revealed that the growth rate of the films and redox kinetics are affected by the differing supports. Specifically, slower PANI film growth was seen on glassy carbon when cycling between 0 to 1 V, while the films were more capacitive on the Pt and Au supports. However, with a larger cycling window for film deposition, the presence of surface oxygen groups was seen on the metal substrates leading to slower film growth.14 This study focuses specifically on graphitic substrates and how their structure and surface properties effect platinum deposition, as well as the growth of PANI film at constant potential. PANI growth was investigated on the surface of the carbon and on the C/Pt surface.For this study, we are using a novel synthetic graphite prod...

Communication—Polyaniline Electrodeposition on Flexible ITO Substrates and the Effect of Curved Electrochemical Conditions

“…The electrode material used during the ECOP process can also have a significant impact on the resulting performance of the PANI film. 13 For instance, it was found that PANI deposited on platinum and gold electrodes behaved differently during hydrogen detection depending on which electrode was used as the substrate during PANI deposition. 14 Furthermore, the beginning of the electropolymerization mechanism (formation of oligomers and oligomer deposition on the electrode) strongly depends on the reactivity of the electrode used; 15 therefore, large differences in polymer properties can be found depending on whether a traditional metal electrode is used, such as a platinum, or whether a transparent semiconducting electrode is used, such as indium-tin oxide (ITO).…”