Upcycling Waste Polyethylene into Carbon Nanomaterial via a Carbon‐Grown‐on‐Carbon Strategy

Abstract

Upcycling waste plastics (e.g., polyethylene (PE)) into value‐added carbon products is regarded as a promising approach to address the increasingly serious waste plastic pollution and simultaneously achieve carbon neutrality. However, developing new carbonization technology routes to promote the oxidation of PE at low temperature and construct the stable cross‐linking network remains challenging. Here, a facile carbon‐grown‐on‐carbon strategy is proposed using carbon black (CB) to convert waste PE into core/shell carbon nanoparticles (CN) in high yields at low temperature. The yield of CN remarkably increases when the heating temperature decreases or the dosage of CB increases. The obtained CN displays turbostratic structure and closely aggregated granular morphology with a size of ≈80 nm. It is found that, prior to the oxidation and carbonization of PE, CB forms a 3D network architecture in the PE matrix. More importantly, CB not only catalyzes the partial oxidation of PE to form PE macromolecular radicals and introduce oxygen‐containing groups at low temperature in the early stage, but also favors for the construction of a stable cross‐linking network in the latter stage. This work offers a facile sustainable strategy for chemical upcycling of PE into value‐added carbon products without post‐treatments or usage of metallic catalysts.

Upcycling of Waste Plastic into Hybrid Carbon Nanomaterials

“…Recent work has shown that carbonization in the presence of carbon black or other conductive amorphous carbons can result in the metal catalyst free formation of turbostratic carbon nanoparticles. [ 29 ] Amorphous carbon can be converted to graphene sheets as the minor side products in CNT formation. [ 26 ] This further supports our observation that the 2D graphene sheets are produced from the carbon black.…”

“…[24][25][26] The growth catalysts generally require dedicated synthesis or templating methods that can be time, energy, and resource intensive. [27][28][29] Further, many of these methods use 1:1 ratios of waste plastic to growth metal complex, meaning that every 1 ton of waste plastic processed would require 1 ton of metal complex to be manufactured, which would hamper widespread implementation and economic viability. [30] To our knowledge, the production of complex carbon hybrid nanomaterials from waste plastic has not been demonstrated.…”

Achieving Both Ultrahigh Electrical Conductivity and Mechanical Modulus of Carbon Films: Templating‐Coalescing Behavior of Single‐Walled Carbon Nanotube in Polyacrylonitrile

“…[5][6][7] However, the less-organized polymeric matrix with mixed phase of amorphous and crystalline regions is converted to a turbostratic structure during carbonization, which results in insufficient performances of carbon films as electrode applications from the perspective of both electrical and mechanical properties. [8][9][10] The graphitic crystallinity of carbon films and their final performance can be enhanced by incorporating different types of carbon nanofillers, including graphene oxide (GO) and single-walled carbon nanotube (SWNT) as the graphitic template. [11][12][13][14][15] In nanocomposites, the interfacial interaction of a polymer and nanofiller dramatically improves the mechanical properties owing to the heterogeneous crystal nucleation of the matrix and intrinsically superior properties of the filler.…”

Mechanochemistry Milling of Waste Poly(Ethylene Terephthalate) into Metal–Organic Frameworks

“…Mechanical recycling usually leads to low‐quality products [8] . In contrast, chemical upcycling, which can convert plastic wastes into high‐quality monomers/oligomers or high‐value chemical products, has drawn great attention for the sustainability and profitability [9–14] . For example, chemical upcycling of PET is being extensively investigated to produce valuable chemicals, materials, and fuels by hydrolysis, solvolysis, hydrogenolysis, pyrolysis, and others [15–18] .…”

“…[8] In contrast, chemical upcycling, which can convert plastic wastes into high-quality monomers/oligomers or high-value chemical products, has drawn great attention for the sustainability and profitability. [9][10][11][12][13][14] For example, chemical upcycling of PET is being extensively investigated to produce valuable chemicals, materials, and fuels by hydrolysis, solvolysis, hydrogenolysis, pyrolysis, and others. [15][16][17][18] Kratish et al employed a carbon-supported single-site molybdenum-dioxo catalyst to selectively depolymerize PET into H 2 BDC and ethylene under 1 bar H 2 atmosphere at 260 °C.…”