Microwave-assisted synthetic routes for single and multicomponent functional nanoparticles

by Miquel Torras, from the Nanoparticles & Nanocomposites (NN) Group at ICMAB-CSIC

Date: Monday, 28 March 2022
Time: 11:00 am
Venue: ICMAB - Sala d'Actes Carles Miravitlles and online session by Zoom. Register here to attend by Zoom.

Abstract: "Nanotechnology is more and more prevalent in many societal domains and industrial sectors. New applications, devices and products resulting from its advances demand new nanomaterials, specifically, nanoparticles with functional properties. Hence, functional nanoparticles have become a very active research field in search of new colloidal systems and novel methods of fabrication. Consequently, well-understood, reproducible, and scalable methods for efficient nanoparticle production are needed. Microwave-assisted synthesis is a versatile synthetic route that can support nanoparticle engineering as this methodology exhibits unique properties and extensive possibilities, which are still to be fully explored.

The thesis reports on novel microwave-assisted chemistry routes for the rational design of single and multicomponent functional nanoparticles. Specifically, contains a complete study on silver nanoparticles by microwave fabrication with a high degree of synthetic control. The nanoparticle formation has been monitored in detail to understand the reaction mechanism. The dissertation also explores the preparation via microwave-synthesis of alloyed hollow nanostructures of metastable compositions such as Rh-Ag and Pd-Ag. It follows by extending microwave routes to more complex systems as the cubic heterostructures combining metal oxides (Cu2O) and metals (Au, Ag, Pd and Pt). Finally, the thesis investigates microwave-obtained gold/titania nanocomposites as photocatalysts for gas-phase hydrogen generation. First, catalysts formed by gold/titania nanoparticles were evaluated and presented an excellent performance for hydrogen generation. Next, novel photocatalysts composed of gold nanoparticles within mesoporous titania 2D-photonic crystals were also studied for hydrogen photo-production. Remarkably, hydrogen production could be extended into the visible by combining light trapping in 2D photonic crystals with plasmonic resonances.

In summary, this Ph.D. thesis has identified and consolidated microwave-assisted chemistry as an innovative synthetic approach for single and multicomponent functional nanoparticle fabrication. More relevant aspects of the dissertation are the achievement of synthetic control for single-component nanoparticles, the attainment of complex metal/metal oxides heterostructures or metastable alloys and the validation of gold/titania systems as photocatalysts for hydrogen production."

Supervisor:

• Anna Roig,  Nanoparticles & Nanocomposites (NN) Group at ICMAB-CSIC

PhD Comittee:

• President: Germán Salazar Alvarez, Uppsala University, Sweden
• Secretary: Leonardo Scarabelli, Institut de Ciència de Materials de Barcelona, Spain
• Vocal: Andreu Cabot Codina, Institut de Recerca en Energia de Catalunya, Spain

University: Universitat Autònoma de Barcelona
PhD Programme: Materials Science Programme

Representative examples of multicomponent functional nanoparticles of the thesis. Au-Cu₂O core-shell nanocubes (left), RhAg alloy hollow nanostructure (top right) and mesoporous TiO₂ photonic crystal film with in-situ grown Au nanoparticles (bottom right).