Preparation of Iron‐ and Nitrogen‐Codoped Carbon Nanotubes from Waste Plastics Pyrolysis for the Oxygen Reduction Reaction

Abstract

A novel method for the preparation of iron‐ and nitrogen‐codoped carbon nanotubes (Fe‐N‐CNTs) is proposed, based on the catalytic pyrolysis of waste plastics. First, carbon nanotubes are produced from pyrolysis of plastic waste over Fe‐Al2O3; then, Fe‐CNTs and melamine are heated together in an inert atmosphere. Different co‐pyrolysis temperatures are tested to optimize the electrocatalyst production. A high doping temperature improves the degree of graphite formation and promotes the conversion of nitrogen into a more stable form. Compared with commercial Pt/C, the electrocatalyst obtained from pyrolysis at 850 °C shows remarkable properties, with an onset potential of 0.943 V versus RHE and a half‐wave potential of 0.811 V versus RHE, and even better stability and anti‐poisoning properties. In addition, zinc–air battery tests are performed, and the optimized catalyst exhibits a high maximum power density.

Hydrogen and Carbon Nanotubes from Pyrolysis-Catalysis of Waste Plastics: A Review

“…Copyright (2014) with permission from Elsevier improved electrocatalytic activity for CNTs produced at higher catalyst temperature, but there was little difference in performance for the CNTs produced from different types of waste plastic. Cai et al [136] have reported on a novel route to produce nitrogen and iron carbon nanotubes with an application as electro-catalysts for the oxygen reduction reaction in fuel cells or metal air batteries. Fe-CNTs were produced from the pyrolysis-catalysis of polypropylene with a Fe-Al 2 O 3 catalyst, followed by co-pyrolysis of the Fe-CNTs with melamine.…”

Recent Advances in Waste Plastic Transformation into Valuable Platinum‐Group Metal‐Free Electrocatalysts for Oxygen Reduction Reaction

“…Through XPS analysis, an obvious difference in the nitrogen species was observed for varying nitrogen‐doping temperatures (Figure 3G) [52] . Between the temperature range of 700 °C and 800 °C nitride‐like species were formed mainly due to the evolution of g‐CN x during the thermal degradation of nitrogen precursor [52,98] .…”

“…Furthermore, carbon is also employed as a support for the PGM‐based electrocatalysts which makes carbon support an essential research theme for ORR applications [48] . Carbon‐based ORR electrocatalysts can be fabricated through the valorization of plastic waste in a facile and cost‐effective way [49–52] . Hence, both ineffective waste management and energy crisis can be addressed simultaneously.…”

“…Cai et al. made a rational attempt to transform disposable PP lunchboxes into iron and nitrogen‐codoped CNTs through catalytic pyrolysis [52] . They used a bi‐stage fixed‐bed reactor with two separate heating zones, where the upper stage was dedicated for the pyrolysis of waste PP feedstock and the lower stage contained iron‐loaded alumina catalysts, at the fixed temperature of 500 °C and 800 °C, respectively.…”

“…From the quantitative analysis of XPS survey scan of waste PET and urea‐derived CNTs, Sridhar and Park observed that nitrogen‐carrying moieties were mainly present in their pyridinic and pyrrolic configurations with relative distribution of 39 % and 61 %, respectively [70] . Following the matching method of heterogeneous doping in the CNTs to uplift the ORR performance, Cai et al developed Fe−N−CNTs and analyzed the effect of second pyrolysis temperature [52] . SEM micrographs confirmed the formation of well‐defined CNTs while the TEM images of prepared Fe−N−CNT at 850 °C demonstrated the encapsulation of nearly 10 nm iron particles between the graphitic layers of CNTs having an outer diameter in the range of 16 nm (Figure 3A–F).…”