Salt melt synthesis of curved nitrogen-doped carbon nanostructures: ORR kinetics boost

Maria Rybarczyk; Emilia Gontarek-Castro; Marek Lieder; Maria-Magdalena Titirici

doi:10.1016/j.apsusc.2017.11.064

Salt melt synthesis of curved nitrogen-doped carbon nanostructures: ORR kinetics boost

Abstract

Implementing metal-free electrocatalysts for the oxygen reduction reaction (ORR) and revealing crucial chemical or topographical parameters driving their activity are vital for the development of power cells. The carbon-based catalysts are very often synthesized through carbonization of biopolymers, in particular, those one containing nitrogen groups such as chitosan. Unfortunately, the resulting carbonaceous materials usually lack specific porosity and exhibit low catalytic activity. Here, we demonstrate that pyrolysis of chitosan in a ZnCl2 melt assisted by the presence of LiCl results not only in a highly porous activated carbon material with a specific surface area of 1317.97 m2/g and the total nitrogen content of 6.5%, but also induces unexpected curvature in the grown graphitic layers. This is the first work that shows curved graphene layers obtained from a biopolymer precursor by its pyrolytic decomposition in the melted salt media. On the other hand, a carbonaceous material obtained from chitosan but without the salts has very low specific surface area of 7.8 m2/g, possesses no specific structural features, and contains 4.7% of nitrogen. The electrochemical studies show, that the former material is highly active towards four-electron pathway of the ORR in terms of an onset potential (0.89 V vs RHE) and the turnover frequency (TOFmax = 0.095 e site−1 s−1). We attribute this high catalytic performance to the presence of the pyridinic and pyrrolic sites in the structure. The ORR kinetics is probably further promoted by curvature in the graphitic layers.

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Authors (4)

Maria Rybarczyk dr inż.
Emilia Gontarek-Castro (formerly: Emilia Gontarek)
Marek Lieder dr hab. inż.
Maria-Magdalena Titirici
- Queen Mary University of London b School of Engineering and Materials Science & Materials Research Institute

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Category:: Articles
Type:: artykuł w czasopiśmie wyróżnionym w JCR
Published in:: APPLIED SURFACE SCIENCE no. 435, pages 543 - 551,
ISSN: 0169-4332
Language:: English
Publication year:: 2018
Bibliographic description:: Rybarczyk M., Gontarek E., Lieder M., Titirici M.: Salt melt synthesis of curved nitrogen-doped carbon nanostructures: ORR kinetics boost// APPLIED SURFACE SCIENCE. -Vol. 435, (2018), s.543-551
DOI:: Digital Object Identifier (open in new tab) 10.1016/j.apsusc.2017.11.064
Verified by:: Gdańsk University of Technology