General synthesis of refractory carbides by low-pressure carbothermal shock reduction

What is it about?

Refractory carbides are attractive candidates for support materials in heterogeneous catalysis because of their high thermal, chemical and mechanical stability. However, the industrial applications of refractory carbides, especially silicon carbide (SiC), are greatly hampered by their low surface area and harsh synthetic conditions, typically have a very limited surface area (<200 m2 g−1) and prepared in a high-temperature environment (>1400°C) that lasts for several or even tens of hours. Based on Le Chatelier’s principle, we theoretically proposed and experimentally verified that a low-pressure carbothermal reduction (CR) strategy was capable to synthesize high-surface-area SiC (569.9 m2 g−1) at a lower temperature and a faster rate (~1300°C, 50 Pa, 30 seconds). Such high-surface-area SiC possesses excellent thermal stability and antioxidant capacity since it maintained stable under a water-saturated airflow at 650°C for 100 hours. Furthermore, we demonstrated the feasibility of our strategy for scale-up production of high-surface-area SiC (460.6 m2 g−1) with a yield larger than 12 grams in one experiment, by virtue of an industrial viable vacuum sintering furnace. Importantly, our strategy is also general in the rapid synthesis of refractory metal carbides (NbC, Mo2C, TaC, WC), and even their emerging high entropy carbides (VNbMoTaWC5, TiVNbTaWC5). Therefore, our low-pressure CR strategy adds a new dimension, not merely limited to temperature and time items, to regulate the synthesis and facilitate the upcoming industrial applications of carbide-based advanced functional materials.

Featured Image

Photo by Hal Gatewood on Unsplash

Photo by Hal Gatewood on Unsplash

Why is it important?

Refractory carbides are emerging as attractive candidates for support materials in heterogeneous catalysis. However, the industrial applications of refractory carbides, especially silicon carbide (SiC), are greatly hampered because of its low surface area and harsh synthetic conditions during available industrial preparation process. Based on Le Chatelier’s principle, we theoretically proposed and experimentally verified that a low-pressure carbothermal reduction strategy was capable of rapid and scalable synthesis of SiC with remarkably high surface area to satisfy the industrial requirement. Furthermore, our strategy is also applicable to the rapid synthesis of refractory metal carbides and even their emerging high-entropy carbides. The rapid synthesis of carbide-based advanced functional materials is beneficial for their performance research and industrial applications.

Perspectives