A Unique Synthesis of Macroporous N-Doped Carbon Composite Catalyst for Oxygen Reduction Reaction.

Ramesh Karunagaran,Cameron Shearer,Tran Thanh Tung,Dusan Losic,Diana Tran

doi:10.3390/nano11010043

Ramesh Karunagaran, Cameron Shearer + Show 3 more

Open Access

https://doi.org/10.3390/nano11010043

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Journal: Nanomaterials	Publication Date: Dec 26, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: University of Adelaide

Abstract

Macroporous carbon materials (MCMs) are used extensively for many electrocatalytic applications, particularly as catalysts for oxygen reduction reactions (ORRs)—for example, in fuel cells. However, complex processes are currently required for synthesis of MCMs. We present a rapid and facile synthetic approach to produce tailored MCMs efficiently via pyrolysis of sulfonated aniline oligomers (SAOs). Thermal decomposition of SAO releases SO2 gas which acts as a blowing agent to form the macroporous structures. This process was used to synthesise three specifically tailored nitrogen (N)-doped MCM catalysts: N-SAO, N-SAO (phenol formaldehyde) (PF) and N-SAO-reduced graphene oxide (rGO). Analysis using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the formation of macropores (100–350 µm). Investigation of ORR efficacy showed that N-SAOPF performed with the highest onset potential of 0.98 V (vs. RHE) and N-SAOrGO showed the highest limiting current density of 7.89 mAcm−2. The macroporous structure and ORR efficacy of the MCM catalysts synthesised using this novel process suggest that this method can be used to streamline MCM production while enabling the formation of composite materials that can be tailored for greater efficiency in many applications.

Highlights

Macroporous carbon materials (MCMs) can be classified as carbonaceous materials with pore sizes >50 nm [1]
Porous carbon catalysts with macropores (150 nm) have demonstrated greater efficacy in oxygen reduction reactions (ORRs) than catalysts with mesopores (12 nm) [11] and, likewise, mesoporous (14 nm) catalysts have outperformed those with micropores (1 nm) [12]
The photographic image of a synthesised sulfonated aniline oligomers (SAOs) is shown in Scheme 1

Summary

Introduction

Macroporous carbon materials (MCMs) can be classified as carbonaceous materials with pore sizes >50 nm [1] These materials are in great demand for many applications due to their large surface area, physiochemical stability, good conductivity and low cost [2]. These materials are widely used in supercapacitors [3], sensing technologies [4], as adsorbents for herbicides [5] and CO2 [6], as well as a catalyst for reactions involving the reduction of oxygen (O2 ) [7] and nitric oxide (NO) [8]. Porous carbon catalysts with macropores (150 nm) have demonstrated greater efficacy in oxygen reduction reactions (ORRs) than catalysts with mesopores (12 nm) [11] and, likewise, mesoporous (14 nm) catalysts have outperformed those with micropores (1 nm) [12]

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