20/11/2020 Conférences

Webinar n° 1 - Gold 2022 : Gold for catalysis

Élodie Boisselier, professeure et chercheure à l’Université Laval (Québec, Canada) et membre international de notre Gdr, vous invite à une série de séminaires virtuels dans le cadre de la conférence GOLD 2022.

Dans le cadre de la conférence internationale Gold 2022, une série de webinars est organisée avec un premier séminaire virtuel le mercredi 25 Novembre 2020 à 17H (heure de Paris).

  • Dr. Prashant K. Jain, PhD. Harvesting the free energy of light using gold

In my talk, I will show that the photoexcitation of plasmon resonances in gold nanoparticles induces new catalytic behavior in gold enabling redox transformations that are otherwise not possible. For instance, we have found that under visible light excitation, gold nanoparticles catalyze the kinetically challenging, multi-electron, multi-proton reduction of CO2 to hydrocarbons. The redox conversion is triggered by energetic electron–hole pairs generated in the gold nanoparticles by interband damping of the plasmon resonance. C–C coupling to form longer hydrocarbons is observed in this light-driven process, which suggests that photoexcitation induces a reaction pathway distinct from that in a thermocatalytic process. The product selectivity is tuned by light intensity and photon energy. Finally, I will show that this scheme goes well beyond photocatalysis: free energy can be harvested from plasmonic excitations of Au nanoparticles and stored in the form of energetic chemical bonds.

  • Audrey Moores, PhD. The Tale of the two Golds: Gold on Chitosan Nanocrystals as a versatile Platform in Catalysis and Mechanochemistry as a novel Method to access Gold Nanoparticles

We explored the use of carboxylated chitin nanocrystals (ChNCs) and their deacetylated versions chitosan nanocrystals (ChsNCs) as support material for gold-based catalysts. ChNCs were initially prepared through the treatment of chitin by ammonium persulfate. ChsNCs were subsequently prepared using an alkaline deacetylation procedure in the presence of NaBH4 to preserve the nanorod structure of the biomaterial. Subsequently, we tested the ability of the as-made ChNCs and ChsNCs as support for Au species. In a reductive environment, these acted as highly active catalysts for the 4-nitrophenol reduction, while the aldehyde–amine–alkyne (A3) coupling reactions functioned very well with these systems, demonstrating the ability to stabilize a Au(I) form. Spectroscopic and imaging techniques confirmed the importance of precisely controlling the redox state of Au as it is being deposited to afford a highly disperse active site on the bionano-support. In another example, we developed a novel synthetic method for the scalable production of gold nanoparticles (NPs) under solvent-free, mechanochemical conditions. The synthesis of Au NPs provided access to monodisperse and ultra-small NPs in the size range of 1–4 nm, without external reducing agents or bulk solvents. Using lignin as a biomass-based reducer, we could access embedded Au NPs of Au in on pot.Sources: Biomacromoleculese 2020, 21, 6, 2236–2245 and Green Chem., 2014, 16 (1), 86-89

La participation à cet événement est gratuite sous réserve d'inscription.

Plus d'informations : http://www.gold2022.org/webinars