|Wednesday, November 25|
Harvesting the free energy of light using gold
* Dr Prashant K. Jain, PhD, Department of Chemistry, University of Illinois Urbana-Champaign, United States
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 electronhole pairs generated in the gold nanoparticles by interband damping of the plasmon resonance. CC 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. Dr Prashant K. Jain, PhD Materials Research Laboratory University of Illinois Urbana-Champaign, United States Prashant K. Jain grew up in Bombay, where he completed his undergraduate education. He obtained his PhD working with M. A. El-Sayed at Georgia Tech, following which he was a postdoctoral fellow at Harvard. After a Miller Fellowship at UC Berkeley, he joined the faculty of the University of Illinois at Urbana-Champaign, where he is an Alumni Scholar and Professor in the Department of Chemistry, Materials Research Lab, and the Beckman Institute. He is also a Richard and Margaret Romano Professorial Scholar and an Affiliate Faculty Member in Physics. His research webpage can be found at https://nanogold.org. Prashant's lab studies lightmatter interactions on the nanoscale. His lab is best known for using nanoscale-confined light for artificial photosynthesis and for probing the workings of complex materials and catalysts. His lab has also expanded the phenomenon of plasmon resonances beyond metal nanostructures to semiconductor nanocrystals. His collective work has been cited over 23,700 times. He has been listed among Highly Cited Researchers by Clarivate Analytics and Elsevier Scopus. Prashant is a Fellow of the Royal Society of Chemistry, a TR35 inventor, a Sloan Fellow, and a recipient of the Presidential Early Career Award in Science and Engineering. He serves on the Editorial Advisory Board of the Journal of Physical Chemistry and is the lead developer of nanoDDSCAT, an open-source computational toolkit for nano-optics and photonics.
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
* Audrey Moores, PhD, Department of Chemistry, McGill University, Canada
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 aldehydeaminealkyne (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 14 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. Audrey Moores, PhD Department of Chemistry McGill University Canada Audrey Moores is an Associate Professor of Chemistry and Tier II Canada Research Chair in Green Chemistry (2007-17) at McGill University, where she started her independent career in 2007. She completed her PhD from the Ecole Polytechnique, France in 2005, under the supervision of Prof. Pascal Le Floch and received the Best Thesis award of the Ecole Polytechnique that year. She was a post-doctoral fellow at Yale University in 2006 under the guidance of Prof. Robert H. Crabtree, funded by a Lavoisier fellowship from the European Union. She is a leading expert in the field of catalysis using metal, metal oxide and biomass-based nanomaterials, with a special emphasis on sustainable processes and use of earth abundant starting materials. Specifically, she has made important discovery towards the use of iron for the important hydrogenation and oxidation catalytic reactions and replace noble metals as catalysts. She is also developing entirely novel methods towards the synthesis of size controlled nanomaterials under solvent-free conditions. She is also studying novel photo catalysts based on plasmonic materials. Her scientific work has been published in 80 high profile, peer reviewed publications, such as J. Am. Chem. Soc., Green Chem., Chem. Comm., or ACS Sustainable Chem. Eng. She also authored 7 book chapters, 1 book and 3 patents (>4700 citations & h-index 35 from Google Scholar). She was elected in 2020 as a Member of the College of the New Scholars, Artists and Scientists of the Royal Society of Canada.