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Core-Shell Nanoparticles for Plasmonics and Catalysis

Kolloquium der Abteilung 5

By doping superfluid droplets of 106 to 1010 helium atoms (HeN) with foreign atoms or molecules, cold complexes of atomic or molecular species are formed that can either be investigated by molecular beam spectroscopic methods or deposited on solid substrates for surface analysis [1]. In this way, large Cu, Ag, Au, Ni, Co, Fe, Pd, Cr, or V2O5 aggregates of different morphology have been generated and deposited on solid carbon, h-BN, or SiN substrates. Employing different pick-up cells for doping the droplets, core-shell clusters of 3 to 6 nm diameter with one metal surrounding a core of a different species are produced. After surface deposition, the samples are removed and various measurement techniques are applied to characterize the created particles: scanning electron microscopy at atomic resolution, electron tomography [2], temperature dependent SEM and TEM up to 1000 degree C, energy-dispersive x-ray spectroscopy (EDXS), electron energy loss spectroscopy (EELS) and optical absorption [3]. By varying the contents of different metals in core-shell particles, we can tune the plasmon resonance [4]. Results of our investigation of the thermal behavior of deposited nanoparticles and the corresponding phase changes and chemical reactivity on the nanoscale will be reported [5, 6]. Vanadium oxides represent a prominent materials class for catalytic applications. On the way towards cluster catalytic experiments, we have shown that V2O5 nanoparticles can be generated by sublimation from the bulk [7] and deposited while keeping the original stoichiometry [8].  

[1] P. Thaler et al., J. Chem. Phys. 143, 134201-1-10 (2015).

[2] G. Haberfehlner et al., Nature Communications 6, 8779-1-6 (2015).

[3] A. Schiffmann et al., J. Appl. Phys. 125, 023104-1-8 (2019).

[4] F. Lackner et al., Eur. Phys. J. D 73, 104(2019).

[5] M. Lasserus et al., Nanoscale 10, 2017-2024 (2018).

[6] M. Schnedlitz et al., ACS Chemistry of Materials 30, 1113−1120 (2018).

[7] M. Lasserus et al., RSC Chemical Science 10, 3473-3480 (2019).

[8] M. Lasserus et al., PCCP 21, 21104-21108 (2019)