Nanoparticles of noble metals absorb and scatter visible light thanks so-called plasmon resonances, light-driven oscillations of their free charge carriers. The energy and spectral shape of these resonances strongly depend on the nanoparticle’s size, shape, composition, and surrounding. Furthermore, their radiative decay (scattering) generates intense electromagnetic fields in the vicinity of the nanoparticle surface that can activate photosensitive processes. On the other hand, their non-radiative decay (absorption) can lead to nanoscale photothermal heating and the generation of non-equilibrium, “hot” charge carriers.
For all of the above reasons, plasmon resonances are used to activate and detect a wide range of chemical and physical phenomena. In our Photoconversion Materials (PCM) group at the VU, we synthesise plasmonic nanomaterials for a variety of applications, from energy conversion and storage, to heterogeneous catalysis, and sensing. Furthermore, we
characterise their photochemical properties using a range of spectroscopy and microscopy techniques, both in ensemble experiments and at the level of single nanoparticles [1-7].
The goal of the present PhD project is to tackle several fundamental questions related to plasmonic activation of chemical reactions, including [8]:
- Can we efficiently harvest plasmonic “hot” charge carriers for photochemical redox reactions?
- What is the role of heating on the photochemical yield under different illumination conditions?
- Can we localize chemistry at the nanoscale via field or thermal hotspots?
- Is plasmon-driven chemistry scalable for 2D material growth and substrate patterning?
To tackle these questions, you will use both our synthetic and characterisation techniques. You will synthesise plasmonic nanoparticles using bottom-up colloidal wet chemical methods and top-down nanolithographic techniques. Furthermore, you will characterise their photochemical properties via ensemble experiments and using single-particle techniques, such as dark-field scattering spectroscopy and microscopy and
in-situ surface-enhanced Raman spectroscopy.
[1] G. Kumari, R. Kamarudheen, E. Zoethout, A. Baldi, Photocatalytic Surface Restructuring in Individual Silver Nanoparticles,
ACS Catalysis 11, 3478-3486 (2021); [2] R.F. Hamans, M. Parente, A. Baldi, Super-Resolution Mapping of a Chemical Reaction Driven by Plasmonic Near-Fields,
Nano Letters XXX, XXXX-XXXX (2020); [3] R. Kamarudheen, G. Kumari, A. Baldi, Plasmon-driven synthesis of individual metal@ semiconductor core@ shell nanoparticles,
Nature Communications 11, 1-10 (2020); [4] R. Kamarudheen, G.J.W. Aalbers, R.F. Hamans, L.P.J. Kamp, A. Baldi, Distinguishing Among All Possible Activation Mechanisms of a Plasmon-Driven Chemical Reaction,
ACS Energy Letters 5, 2605-2613 (2020); [5] M. Parente, M. van Helvert, R.F. Hamans, R. Verbroekken, R. Sinha, A. Bieberle-Hütter, A. Baldi, Simple and Fast High-Yield Synthesis of Silver Nanowires,
Nano Letters 20, 5759-5764 (2020); [6] M. Parente, S. Sheikholeslami, G.V. Naik, J.A. Dionne, A. Baldi, Equilibration of Photogenerated Charge Carriers in Plasmonic Core@ Shell Nanoparticles,
The Journal of Physical Chemistry C 122, 23631-23638 (2018); [7] R. Kamarudheen, G.W. Castellanos, L.P.J. Kamp, H.J.H. Clercx, A. Baldi, Quantifying photothermal and hot charge carrier effects in plasmon-driven nanoparticle syntheses,
ACS Nano 12, 8447-8455 (2018); [8] E. Cortés, L. V. Besteiro, A. Alabastri, A. Baldi, G. Tagliabue, A. Demetriadou, P. Narang, Challenges in Plasmonic Catalysis,
ACS Nano 14, 16202–16219 (2020).