Poli (Vinilpirrolidona) adsorvida em platina: influência na eletro-oxidação de alcoóis

Abstract

It is well-known that nanocatalysts are more efficient than their microcrystalline counterparts. A feature common to most of these systems is the presence of a stabilizing agent on their surface to prevent excessive growth and aggregation. Thus, the surface of a catalyst is intrinsically modified by the polymer and the impact of the latter must not be neglected. Given this background, the effect of adsorbed PVP on the electro-oxidations of methanol, ethanol, 2-propanol, ethylene glycol and glycerol was investigated using platinum as working electrode. PVP is a polymer widely employed for stabilization of nanoparticles, thus it is imperative to determine its influence on technological-appealing reactions, such as those involved in fuel cells. Through cyclic voltammetry (CV), we found out that the presence of PVP on platinum increased the onset electro-oxidation potential of all alcohols, which indicates that PVP delays the formation of surface oxides indispensable to the electro-oxidation of alcohols. In addition, the presence of PVP led to a decrease in the current densities. In situ FTIR revealed that alterations in the catalytic activity are probably due to changes of reaction pathways induced by the presence of PVP. The present study emphasizes that stabilizing agents have a profound impact on electrochemical processes, hence it is imperative that one understands the way they act to carry out a proper analysis.