Direct evidence of atomic-scale structural fluctuations in catalyst nanoparticles
Pin Ann Lin, Jose Gomez-Ballesteros, Juan Burgos, Perla Balbuena, Bharath N. Natarajan, Renu Sharma
A heterogeneous catalyst usually works by letting the reactant adsorb onto its surface where the energies for specific bonds to dissociate and/or combine with other species (to form desired intermediate or final products) are lower. Rational catalyst design requires a solid definition of its role in material syntheses. Therefore, exact chemical pathways of reactants in the presence of a catalyst are critical to define their functionality. We show, using SWCNT formation, that chemical pathway may be via the formation of metastable phases with lower energy of formation than the final product. Here, we scope out the role of phase transitions occuring in an individual transition metal catalyst nanoparticle during single walled carbon nanotube growth by using automated time resolved structural analysis of atomicaly resolved images extracted from videos recorded using in situ environmental transmission electron microscopy. In addition, we track the spatial and temporal evolution of the distribution of carbon atoms by performing reactive molecular dynamics simulations. We show that the observed rates of structural fluctutions in catalyst nanoparticle, due to the formation and decomposition of a metal carbide phase, are related to nanotube growth. We anticipate that such combination of real-time atomic resolution image analysis and the molecular dynamics simulations will facilitate the catalyst design to improve reaction efficiencies and growth of selective structures.
, Gomez-Ballesteros, J.
, Burgos, J.
, Balbuena, P.
, Natarajan, B.
and Sharma, R.
Direct evidence of atomic-scale structural fluctuations in catalyst nanoparticles, Journal of Catalysis, [online], https://doi.org/10.1016/j.jcat.2017.03.009, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=920329
(Accessed October 20, 2021)