title: Atomic-Scale Mechanism on Nucleation and Growth of Mo2C Nanoparticles Revealed by in Situ Transmission Electron Microscopy.
abstract: With a similar electronic structure as that of platinum, molybdenum carbide (Mo2C) holds significant potential as a high performance catalyst across many chemical reactions. Empirically, the precise control of particle size, shape, and surface nature during synthesis largely determines the catalytic performance of nanoparticles, giving rise to the need of clarifying the underlying growth characteristics in the nucleation and growth of Mo2C. However, the high-temperature annealing involved during the growth of carbides makes it difficult to directly observe and understand the nucleation and growth processes. Here, we report on the use of advanced in situ transmission electron microscopy with atomic resolution to reveal a three-stage mechanism during the growth of Mo2C nanoparticles over a wide temperature range: initial nucleation via a mechanism consistent with spinodal decomposition, subsequent particle coalescence and monomer attachment, and final surface faceting to well-defined particles with minimum surface energy. These microscopic observations made under a heating atmosphere offer new perspectives toward the design of carbide-based catalysts, as well as the tuning of their catalytic performances.
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Linfeng
authors.initials: L
authors.lastname: Fei
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Sheung Mei
authors.initials: SM
authors.lastname: Ng
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.affiliation: School of Materials Science and Engineering, Nanchang University , Nanchang, Jiangxi 330031, China.
authors.forename: Longlong
authors.initials: L
authors.lastname: Shu
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Wei-Bing
authors.initials: WB
authors.lastname: Zhang
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Zehui
authors.initials: Z
authors.lastname: Yong
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Tieyu
authors.initials: T
authors.lastname: Sun
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Chi Hang
authors.initials: CH
authors.lastname: Lam
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Chi Wah
authors.initials: CW
authors.lastname: Leung
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China.
authors.forename: Chee Leung
authors.initials: CL
authors.lastname: Mak
authors.affiliation: School of Materials Science and Engineering, Nanchang University , Nanchang, Jiangxi 330031, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
keywords: Transmission electron microscopy; crystal growth; in situ heating; molybdenum carbide; nanoparticles; nucleation