Abstract
One of the most challenging targets in oxygen reduction reaction (ORR) electrocatalysts based on N-doped carbon materials is the control of the pore structure and obtaining nanostructured thin films that can easily be incorporated on the current collector. The carbonization of nitrogen-containing polymers and the heat treatment of a mixture of carbon materials and nitrogen precursor are the most common methods for obtaining N-doped carbon materials. However, in this synthetic protocols, the surface area and pore distribution are not controlled. This work enables the preparation of 2D-ordered N-doped carbon materials through the carbonization of 2D polyaniline. For that purpose, aniline has been electropolymerized within the porous structure of two different templates (ordered mesoporous Silica and ordered mesoporous Titania thin films). Thus, aniline has been impregnated into the porous structure and subsequently electropolymerized by means of chronoamperometry at constant potential. The resultant samples were heat-treated at 900 °C with the aim of obtaining 2D N-doped carbon materials within the template structures. Polyaniline and polyaniline-derived carbon materials have been analyzed via XPS and TEM and characterized by electrochemical measurements. It is worth noting that the obtained 2D-ordered mesoporous N-doped carbon materials have proved to be highly active electrocatalysts for the ORR because of the formation of quaternary nitrogen species during the heat treatment.
Highlights
The oxygen reduction reaction (ORR), occurring in the cathode electrode of the fuel cells (FCs), is one of the main limitations of these devices because of the slow reaction rate and high overpotential of the reaction [1,2]
We report a method to synthesize N-doped ordered mesoporous carbon materials thin films with high control over the N active sites towards oxygen reduction reaction and maintaining a well-ordered porosity
Two-dimensional-orderedpolyaniline polyaniline thin thin film film was was successfully successfully prepared potentiostatic polymerizationofofaniline anilinewithin withinthe the porous porous structure structure of two potentiostatic polymerization two ordered ordered mesoporous mesoporous templates: Silica and Thepolymerization polymerization time time permits permits to templates: Silica and to control control the the amount amountofofpolymer polymer electrodeposited on the surface of the templates
Summary
The oxygen reduction reaction (ORR), occurring in the cathode electrode of the fuel cells (FCs), is one of the main limitations of these devices because of the slow reaction rate and high overpotential of the reaction [1,2]. The main problem of these routes of synthesis is the non-control over the porosity and surface area In this sense, we report a method to synthesize N-doped ordered mesoporous carbon materials thin films with high control over the N active sites towards oxygen reduction reaction and maintaining a well-ordered porosity. Once the electropolymerization was performed, the samples were heat-treated with the aim of creating highly active species in the resultant composite nitrogen-doped mesoporous carbon material/template. This methodology permits an excellent control over the amount of N-doped carbon material and the chemical nature of the N species. The electrochemical behavior and physicochemical properties of the prepared samples were determined by XPS, TEM, and cyclic voltammetry in presence and absence of dioxygen in the alkaline electrolyte
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