Synthesis of silicon carbide nanocrystals from waste polytetrafluoroethylene

Room Temperature Defluorination of Poly(tetrafluoroethylene) by a Magnesium Reagent

Perfluoroalkyl substances (PFAS) are pervasive in the environment. The largest single use material within the PFAS compound class is poly(tetrafluoroethylene) (PTFE), a robust and chemically resistant polymer. Despite their widespread use and serious concerns about their role as pollutants, methods for repurposing PFAS are rare. Here we show that a nucleophilic magnesium reagent reacts with PTFE at room temperature, generating a molecular magnesium fluoride which is easily separated from the surface-modified polymer. The fluoride in turn can be used to transfer the fluorine atoms to a small array of compounds. This proof-of-concept study demonstrates that the atomic fluorine content of PTFE can be harvested and reused in chemical synthesis.

Selective Thermal Transformation of Automotive Shredder Residues into High-Value Nano Silicon Carbide

Automotive waste represents both a global waste challenge and the loss of valuable embedded resources. This study provides a sustainable solution to utilise the mixed plastics of automotive waste residue (ASR) as a resource that will curtail the landfilling of hazardous waste and its adverse consequences to the environment. In this research, the selective thermal transformation has been utilised to produce nano silicon carbide (SiC) using mixed plastics and glass from automotive waste as raw materials. The composition and formation mechanisms of SiC nanoparticles have been investigated by X-ray diffraction (XRD), X-ray-Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The as synthesised SiC nanoparticles at 1500 °C has uniform spherical shapes with the diameters of the fixed edges of about 50–100 nm with a porous structure. This facile way of synthesising SiC nanomaterials would lay the foundations for transforming complex wastes into value-added, high-performing materials, delivering significant economic and environmental benefits.

Taming Polysulfides in an Li-S Battery With Low-Temperature One-step Chemical Synthesis of Titanium Carbide Nanoparticles From Waste PTFE

In this work, titanium carbide (TiC) nanoparticles have been successfully synthesized at much lower temperatures of 500°C using cheaper starting materials, such as waste polytetrafluoroethylene (PTFE) (carbon source) and titanium and metallic sodium, than the traditional carbothermal reduction of TiO₂ at 1,800°C. An XRD pattern proved the formation of face-centered cubic TiC, and TEM images showed the obtained TiC nanoparticles with an average size of approximately 50 nm. In addition, the separator coated with TiC nanoparticles as an active material of interlayer effectively mitigates the shuttling problem by taming the polysulfides in Li–S batteries compared with a traditional celgard separator. The assembled cell realizes good cycling stability with 501 mAh g⁻¹ and a low capacity fading of 0.1% per cycle after 300 cycles at 1 C due to high utilization of the sulfur-based active species.

Converting Waste Polyethylene into ZnCCo3 and ZnCNi3 by a One-Step Thermal Reduction Process

Plastic products have brought us great convenience in our daily life and work. But in the meantime, waste plastics have become solid pollutants in the environment due to its poor degradability. The resource utilization of waste plastic can decrease environmental pollution. Here, a thermal reduction method for the conversion of waste polyethylene to ZnCCo₃ and ZnCNi₃ in a stainless-steel autoclave under mild conditions has been reported. X-ray powder diffraction patterns indicate that the obtained samples are anti-perovskite-structured ternary carbides (ZnCCo₃ and ZnCNi₃) with good crystallinity. Moreover, the formation mechanism of ternary carbides has been briefly discussed. This method can be developed into an effective method for disposal of other waste plastics.

Facile Synthesis of Mo2C Nanoparticles from Waste Polyvinyl Chloride

The resource utilization of waste plastic can not only control environmental pollution but can also ease up the problems of lack of energy resources. In this study, molybdenum carbide (Mo₂C) nanoparticles have been synthesized by utilizing waste polyvinyl chloride as a carbon source in a stainless-steel autoclave at 600 °C. X-ray diffraction pattern indicates that the product is orthorhombic phase Mo₂C. Electron microscopy photographs show that the obtained Mo₂C product consisted of crystalline nanoparticles with an average size of 50 nm. The possible formation mechanisms of Mo₂C have been also briefly discussed on the basis of the structures of the products synthesized with different reaction times. The effects of reaction temperature on the crystallinity and microstructure of the obtained products have been investigated. The results show that higher reaction temperature promotes the formation of Mo₂C with high crystallinity.

Study on the synthesis of β-SiC nanoparticles from diamond-wire silicon cutting waste

Large amounts of silicon have been wasted as silicon cutting waste (SCW) during the silicon wafer production process, which increases the cost of photovoltaic solar cells and causes environmental pollution. In this paper, an innovative approach for producing β-SiC nanoparticles by using SCW as silicon source and sucrose as carbon source is reported. The synthesized β-SiC nanoparticles were characterized by XRD, FTIR, SEM, TEM, Raman, PL and DSC. The results showed that β-SiC nanoparticles were successfully prepared with a particle size ranging from 40 to 50 nm, and have special photoluminescence as well as good thermal stability. The recycling of SCW can not only solve the environmental pollution issue but also benefits the economy.

β-SiC nanoparticles was synthesized using silicon cutting waste (SCW) as silicon source and sucrose as carbon source.

One step conversion of waste polyethylene to Cr3C2 nanorods and Cr2AlC particles under mild conditions

Carbides (Cr₃C₂ and Cr₂AlC) have been synthesized by using waste PE as a carbon source in an autoclave under mild conditions.