We have developed a simple method to prepare nano-(ZrC0.93, ZrO2-polymorphs)@carbon composites with graphite/amorphous carbon content and adjustable Zr/C ratio based on using a multistep tube furnace and plasma-assisted heat treatment of zirconium-loaded sulfonated styrene–divinylbenzene (STY-DVB) copolymers. Pre-pyrolysis of zirconium-loaded sulfonated STY-DVB ion exchangers with 2 and 8 mass % DVB at temperatures between 1000 and 1400 °C for 2 h produced nano-ZrO2@C intermediates with particle sizes of ~ 30–60 nm with no ZrC formation. Plasma processing of nano-ZrO2@C resulted in nano-(ZrC0.93, ZrO2)@C composites with 11% (under a He atmosphere) (C/Zr = 73) or 13% (under a H2 atmosphere) (C/Zr = 58) ZrC0.93 content. Three polymorphs of the zirconium dioxide (tetragonal, monoclinic and cubic, between 18 and 27 nm) were found in the products. The amounts of tetragonal and monoclinic ones are comparable to that of ZrC0.93. The average particle size of ZrC0.93 prepared in this way was found to be 21–23 nm. The BET surface area of the nano-(ZrC0.93, ZrO2)@C(graphite) composites prepared in He and H2 was over 250 and 300 m2/g, respectively. We developed a reproducible and easy method to prepare nano-(ZrC, ZrO2)@C products by setting the DVB content, sulfonation degree, Zr loading and the thermal treatment conditions, which have an influence on the ZrC and graphite/amorphous carbon content of nano-ZrO2@C intermediates. The zirconium-loaded sulfonated styrene–divinylbenzene (STY-DVB) copolymers (2 and 8 mass% DVB) or their thermal decomposition was characterized with vibrational spectroscopy, thermal analysis and DSC or powder XRD, BET, XPS and HRTEM methods, respectively.
Synthesis of zirconium carbide (ZrC) powder was investigated applying a non-conventional atmospheric radiofrequency (RF) thermal plasma process. In one case, zirconium dioxide (ZrO2) was reacted with solid carbon or with methane with varying molar ratio. In the other, zirconium-propoxide (NZP), containing both constituents, was thermally decomposed in the Ar plasma. Temperature-dependent thermodynamic analysis was performed in the 500-5500 K temperature range to estimate the formation of possible equilibrium products for each reaction stoichiometry. Broad temperature range exists for the stability of solid ZrC for each explored reaction system. In accordance with this prediction, X-ray diffraction studies detected the ZrC as the major phase in all the prepared powders. The yield of particular runs ranged from 39 % to 98 %. Practically, full conversion was typical for the case of NZP precursor, however only partial conversion could be detected in ZrO2 reactions. The average particle size of the powders falls between 10 nm and 100 nm depending on the type of the reaction systems (either calculated from the specific surface area or derived from broadening the XRD reflections). The transmission electron micrographs indicated mostly globular shape of the nanosize particles. Quantitative analysis of the surface of the powders by X-ray photoelectron spectroscopy revealed the presence of oxygen and carbon. Evaluating the spectra of the powders prepared from NZP, and taking in the account its spherical shape, a ZrC core covered by a very thin (≈1.0 nm) ZrO2 layer may be accounted for the measured oxygen and a thicker carbonaceous layer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.