Metal–Support Interactions of Platinum Nanoparticles Decorated N-Doped Carbon Nanofibers for the Oxygen Reduction Reaction

Abstract

N-doped carbon materials are discussed as catalyst supports for the electrochemical oxygen reduction reaction (ORR) in fuel cells. This work deals with the preparation of Pt nanoparticles (NPs) supported on N-doped carbon nanofibers (N-CNF) from a polyaniline nanofiber (PANI NF) precursor, and investigates the ORR activity of the produced materials. Initially, Pt NPs are deposited on PANI NFs. The PANI NF precursors are characterized by near-edge X-ray absorption fine structure (NEXAFS) and transmission electron microscopy (TEM) measurements. It is shown, that in the PANI NF precursor materials electrons from the Pt are being transferred toward the π-conjugated systems of the aromatic ring. This strong interaction of Pt atoms with PANI explains the high dispersion of Pt NPs on the PANI NF. Subsequently, the PANI NF precursors are carbonized at different heattreatment conditions resulting in structurally different N-CNFs which are characterized by NEXAFS, X-ray photoelectron spectroscopy (XPS) ,and TEM measurements. It is shown that an interaction between N-groups and Pt NPs exists in all investigated N-CNFs. However, the N-CNFs differ in the composition of the N-species and the dispersion of the Pt NPs. A small mean Pt NP size with a narrow size distribution is attributed to the presence of pyrdinic N-groups in the N-CNFs, whereas, for the N-CNFs with mainly graphitic and pyrrolic N-groups, an increase in the average Pt NP size with a broad size distribution is found. The ORR activity in alkaline media investigated by Koutecky−Levich analysis of rotating disk electrode measurements showed a largely enhanced ORR activity in comparison to a conventional Pt/C catalyst.

Electrocatalytic Activity and Stability of 3D Ordered N‐doped Hierarchically Porous Carbon Supported Pt Catalyst for Methanol Oxidation and Oxygen Reduction Reactions

“…From the high‐resolution XPS spectrum of the C 1s (Figure b), C−C, C−N, C−O and C=O bonds are observed. The N 1s spectrum of Pt/N‐OHPC (Figure c) shows five peaks, assigning to pyridinic N (398.2 eV), Pt−N bond (399.0 eV), pyrrolic N (399.8 eV), graphitic N (401.1 eV) and N−O bond (402.5 eV) . It was reported that graphitic N could increase the electronic conductivity of carbon materials and pyridinic and pyrrolic N can increase active sites for ORR, which are both important for electrochemical reaction.…”

Understanding Heteroatom-Mediated Metal–Support Interactions in Functionalized Carbons: A Perspective Review

“…Moreover, other peaks can appear due to π* transitions deriving from the introduction of functionalities (e.g., amine or imide groups) [89].…”

Cobalt and Nitrogen Codoped Carbon Nanosheets Templated from NaCl as Efficient Oxygen Reduction Electrocatalysts

“…[6] The most active catalystf or ORR, platinum-based catalysts, cannotb ew idely used on account of their high cost, inferior long-termd urability [7] andl ow tolerance to the intermediate products in fuel cells. [8] Developing cheap, high-activity low- [9] or non-platinum [10] catalysts is the immediate way to solve these problems. In the last decade, heteroatom-doped (N, P, S, B) carbon materials were thought to be ap romising alternative to platinum in the ORR.…”