Phase controlled synthesis of transition metal carbide nanocrystals by ultrafast flash Joule heating
Abstract
Nanoscale carbides enhance ultra-strong ceramics and show activity as high-performance catalysts. Traditional lengthy carburization methods for carbide syntheses usually result in coked surface, large particle size, and uncontrolled phase. Here, a flash Joule heating process is developed for ultrafast synthesis of carbide nanocrystals within 1 s. Various interstitial transition metal carbides (TiC, ZrC, HfC, VC, NbC, TaC, Cr2C3, MoC, and W2C) and covalent carbides (B4C and SiC) are produced using low-cost precursors. By controlling pulse voltages, phase-pure molybdenum carbides including β-Mo2C and metastable α-MoC1-x and η-MoC1-x are selectively synthesized, demonstrating the excellent phase engineering ability of the flash Joule heating by broadly tunable energy input that can exceed 3000 K coupled with kinetically controlled ultrafast cooling (>104 K s−1). Theoretical calculation reveals carbon vacancies as the driving factor for topotactic transition of carbide phases. The phase-dependent hydrogen evolution capability of molybdenum carbides is investigated with β-Mo2C showing the best performance.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 11, 2022
- Source ID
- 10.1038/s41467-021-27878-1
Entities
People
- Bing Deng
- Boris I Yakobson
- Duy Xuan Luong
- Guanhui Gao
- James Tour
- John Tianci Li
- Robert A. Carter
- Weiyin Chen
- Yufeng Zhao
- Zhe Wang
Organizations
- Air Force Office of Scientific Research
- Rice University