Analysis of Electrochemical Behavior of Carbon Nanomaterials Doped with Sulfur and Their Use As Support of Pt Nanoparticles

Abstract

The importance of finding new environmental friendly options for generation of energy, has taken more relevance in recent years. In this context, fuel cells have been recognized as a promising option to produce clean energy. The fuel cells have two main components: an electrolyte and two electrodes (an anode and a cathode), the latter usually is manufacturaded with precious metal supported on carbon (i. e. Pt/C), to its high electrocatalytic activity in the oxygen reduction reaction (ORR). However, the high cost of platinum, have pushed the research focus in alternatives to replace or decrease this material in the electrodes. Recent research works have shown that low platinum electrocatalyst supported on carbons doped with heteroatoms (e.g. B, N, P and S) have similar electrocatalytic activities to the conventional Pt/C for ORR. On the other hand, carbon nanotubes have unique properties that make them excellent candidates for using as electrocatalyst support. This work shows a sulfur-doped carbon nanomaterials synthesized by a modified chemical vapor deposition method. Toluene and thiophene were used as sources of carbon and sulfur, respectively. Ferrocene was used as a catalytic agent. Chemical reduction method was used to incorporate Pt nanoparticles to the doped materials. Physical and chemical characterization was performed by X-Ray Diffraction and Scanning Electron Microscopy, in order to determinate structural and morphological properties. The chemical elemental analysis was done by energy dispersive spectroscopy. The electrochemical performance of sulfur-doped carbon nanomaterials with and without nanoparticles of Pt was evaluated using cyclic voltammetry (CV) and rotating disk electrode (RDE) in acid media. Additionally, a preliminary modeling of the electrochemical behavior of doped materials obtained is presented. The model was performing using the Functional Theory Density (DFT) to explain the phenomena occurring during the ORR and the effect of modifying carbon structures with dopant S on this reaction.