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Early Transition Metal Nano-carbides and Nanohydrides from Solid-State Metathesis initiated at Room Temperature
Transition metal carbides (TMCs) have attracted great interest due to their mechanical and catalytic properties but their syntheses generally require energy-consuming processes with temperatures above 800 °C. We report here a solid-state metathesis reaction between metal chlorides (ZrCl 4 , NbCl 5 ,...
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Published in: | Green chemistry : an international journal and green chemistry resource : GC 2021 |
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Main Authors: | , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Transition metal carbides (TMCs) have attracted great interest due to their mechanical and catalytic properties but their syntheses generally require energy-consuming processes with temperatures above 800 °C. We report here a solid-state metathesis reaction between metal chlorides (ZrCl 4 , NbCl 5 , MoCl 3 , MoCl 5 , HfCl 4 , TaCl 5 , WCl 6) and potassium dispersed in carbon (graphite or acetylene black). The reaction is initiated at room temperature or with gentle heating below 75 °C. Within seconds, it produces carbon-supported carbide or metallic nanoparticles of diameter below 50 nm. The phase speciation depends on the metal and different process parameters. In some cases (ZrCl 4 , NbCl 5 , HfCl 4 , TaCl 5), the metal is further converted into a hydride upon neutralization of the reaction crude with ethanol. The products were characterized by powder X-ray diffraction (PXRD) and Transmission Electron Microscopy (TEM). Based on thermodynamic and kinetic considerations, we propose a mechanism explaining the coexistence of several phases (metal, carbide, hydride) and their occurrence at each step of the reaction. |
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ISSN: | 1463-9262 1463-9270 |
DOI: | 10.1039/D1GC01097B |