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NanoPhotoChemistry (NPC)

Andrea_2020
Dr. Andrea Baldi
Associate Professor

Nanostructured materials exhibit a wide range of interesting optical phenomena. For example, metal nanoparticles strongly absorb and scatter visible light via so-called plasmon resonances, while regular arrays of nanoparticles exhibit collective optical phenomena that strongly depend on their geometric arrangement.

In the NPC group we exploit a range of nanophotonic effects to drive, steer, and detect chemical and physical processes at the nanoscale.

In particular, we synthesize nanomaterials for energy conversion and storage, heterogeneous catalysis, nanomaterials synthesis, and sensing applications and characterize their photochemical properties in ensemble experiments and at the level of single nanoparticles.

Our group brings together a diverse group of scientists with backgrounds in physics, chemistry, and materials science.

Join us
If you are interested in joining us for a bachelor or master project or if you would like to apply for a PhD or a postdoc position, you can find us at a.baldi@vu.nl

Current research projects 

1) Photosynthesis of nanomaterials. We exploit optical resonances in metal (plasmonic) nanoparticles to enhance light absorption and scattering and drive the (photo)synthesis of hierarchical nanostructures such as metal@metal and metal@semiconductor core@shell nanostructures. Throughout several experiments we demonstrated the power of plasmon resonances to activate and control nanomaterial synthesis both in ensemble and at the single particle level. 

2) Super-resolution microscopy. Conventional optical microscopy techniques are limited by diffraction to spatial resolutions of the order of the wavelength used, typically of the order of several hundreds of nanometers. Fluorescence microscopy, in which fluorescent molecules are used as light probes, allows to beat such diffraction limit, if the fluorescent molecules are emitting over sufficiently spaced time frames. By collecting the stochastic emission of a few fluorescent molecules at a time, we can achieve spatial resolutions of a few nanometers and begin to investigate the properties of nanoscale materials. In the NPC group we use super-resolution fluorescence microscopy to spatially map the emission properties of metal nanoparticle arrays and the photochemical reactivity of individual metal nanoparticles.

3) Synthesis of colloidal metal nanoparticles. Several advanced optoelectronic devices rely on the synthesis and control of nanoscale materials, such as nanoparticles, core@shell nanostructures, nanowires, etc. In the NPC group we develop and optimize the synthesis of a diverse range of nanomaterials, using colloidal wet chemistry.
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4) Nanophotonic sensing. Thanks to their light focusing properties and their sharp and tunable optical resonances, nanomaterials are ideally suited to detect chemical and physical processes at the nanoscale using light. In the NPC group we utilize nanophotonic resonances in both single nanoparticles and in collective nanoparticle arrays, to detect ultra-low concentrations of gasses, measure surface restructuring of catalysts, and identify reaction intermediates of heterogeneous catalytic reactions.

5) Strong coupling. Resonances in traditional optical cavities, such as parallel mirrors, have been used to modify the potential energy landscape of chemical reactions and affect their output. This phenomenon occurs because of the strong interaction (or strong coupling) between the cavity resonance and the electronic or vibrational transitions of the reactant molecules. Nanophotonics offers an unprecedented range of opportunity to explore strong coupling for tailoring of chemical reactions. In our group we are exploring the use of strong coupling driven chemicql reactivity in open cavities composed of metal nanoparticle arrays.

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Group’s recent publications
(see also here)

•    R. Kamarudheen, G. Kumari, and A. Baldi, Plasmon-driven synthesis of individual metal@ semiconductor core@ shell nanoparticles, Nature Communications 2020, 11:3957
•    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 2020, 5, 2605-2613
•    M. Parente, M. van Helmert, R. F. Hamans, R. Verbroekken, R. Sinha, A. Bieberle-Hütter, and A. Baldi, Simple and Fast High-Yield Synthesis of Silver Nanowires, Nano Letters 2020, 20, 5759-5764
•    G. Baffou, I. Bordacchini, A. Baldi, and Romain Quidant, Simple experimental procedures to distinguish photothermal from hot-carrier processes in plasmonics, Light: Science & Applications 2020, 9, 1-16
•    N. van Hoof, M. Parente, A. Baldi, and J. Gómez Rivas, Terahertz Time-Domain Spectroscopy and Near-Field Microscopy of Transparent Silver Nanowire Networks, Advanced Optical Materials 2020, 8, 1900790
•    Hamans, M. Parente, G. W. Castellanos, M. Ramezani, J. Gómez Rivas, and A. Baldi, Super-resolution Mapping of Enhanced Emission by Collective Plasmonic Resonances, ACS Nano 2019, 13, 4514-4521
•    Baldi, L. P. A. Mooij, V. Palmisano, H. Schreuders, G. Krishnan, B. J. Kooi, B. Dam, and R. Griessen, Elastic versus alloying effects in Mg-based hydride films, Physical Review Letters 2018, 121, 255503
•    R. Kamarudheen, G. Castellanos Gonzales, L. Kamp, H. Clercx, and A. Baldi, Quantifying photothermal and hot charge carrier effects in plasmon-driven nanoparticle syntheses, ACS Nano 2018, 12, 8447-8455
•    M. Parente, S. N. Sheikholeslami, G. V. Naik, J. A. Dionne, and A. Baldi, Equilibration of Photogenerated Charge Carriers in Plasmonic Core@Shell Nanoparticles, The Journal of Physical Chemistry C 2018, 122, 23631-23638