|Monday, July 18|
Artificial strong metal-support interaction on plasmonic core-shell nanostructures for higher selectivity and activity toward H2 generation
Vien-Duong Quach, Université Paris-saclay, France
Maria Chiara Spadaro, Catalan Institute of Nanoscience and Nanotechnology (ICN2), Spain
Jordi Arbiol, Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC & BIST, Spain
Christophe Colbeau-Justin, Université Paris-saclay, France
* Mohamed Nawfal Ghazzal, Université Paris-saclay, France
Solar energy conversion using photocatalysis becomes a subject of great interest with important potential applications in environment, such as chemical fuel production (H2) [1,2,3]. Titanium dioxide (TiO2) is by far the most popular semiconductor used in photocatalysis. However, TiO2 has a large band gap and can only be excited by UV light. Furthermore, the fast recombination of electron-hole pairs lowers the solar energy conversion efficiency. In this context, engineering photocatalyst based on gold nanoparticles (AuNPs) has attracted great attention for the solar-to-energy conversion due to their multiple and unique properties . However, there are ambiguities regarding the plasmonic photocatalyst configuration and the mechanism behind the photocatalytic production of H2 in core-shell system. In this presentation, the rate of H2 production over designed mutually reverse configurations, SiO2@Au@TiO2 and SiO2@TiO2@Au, as well as the effect of the AuNPs loading will be discussed. We found an improvement of the photocatalytic hydrogen efficiency, boosted by the TiO2 thin overlayer covering finely dispersed AuNPs, forming a strong metal-support interaction (SMSI) compared to conventional system. Furthermore, the pathway of the charge carrier’s dynamics occurred regarding the system configuration are found to be different. The photogenerated electrons are collected by AuNPs in classical SiO2@TiO2@Au system, while, unconventionally, they are injected back in the titania surface for SMSI SiO2@Au@TiO2 system. Additionally, the adsorption energy of methanol, theoretically estimated using density functional theory (DFT) methodology, is lower for soft-chemistry SMSI photocatalyst compared to conventional system, accelerating the kinetic of photocatalytic hydrogen production. Moreover, and while the majority of the reports suggested that the SMSI was restricted to metals from group VI, VII and VIII, we have demonstrated that it is also possible to extended to other metal transition in the periodic table, such as Pt, Au, Au and Ni. Herein, we aim to pinpoint the behind mechanism for the superior activity and selectivity towards hydrogen evolution reactions using new concept involving the construction of “Strong metal-support interaction” and demonstrate that SMSI is more efficient compared to classical system for Au nanoparticles and variety of metals.
Au deposition onto (B- or C-) doped g-C3N4/ TiO2 heterojunctions for enhanced CH4 production from visible-light driven gas phase CO2 photoreduction with water
* Valérie Keller, ICPEES (institute of Chemistry and processes for Energy, Environment and Health, CNRS/University of Strasbourg, France
Leila Hammoud, ICPEES (institute of Chemistry and processes for Energy, Environment and Health, CNRS/University of Strasbourg, France
Valérie Caps, ICPEES (institute of Chemistry and processes for Energy, Environment and Health, CNRS/University of Strasbourg, France
Here, we synthesized for the first time ternary composites Au/C- or B- doped g-C3N4/TiO2 via a wet impregnation method, exhibiting enhanced CO2 photoreduction properties by elaborate efficient Au/(doped)gC3N4-TiO2 photocatalysts by optimizing the different functions of the nanocomposite material, namely high quality gC3N4-TiO2 heterojunction for improved visible-light absorption and better charger carrier separation, and Au NPs engineering for enhanced co-catalytic properties and Surface Plasmon Induced Effects (SPIE) for visible light harvesting. These enhanced activities are attributed to a combination of extended absorption of doped C3N4 in the visible range, high quality heterojunction between doped g-C3N4 and TiO2 and optimum Au NPs particles size, loading and dispersion.
New Applications of Gold(I)-Catalyzed Cross Coupling Promoted by Photosensitization
* Louis Fensterbank, Sorbonne Université, France
A novel access to 2,3-disubstituted indoles from o-alkynyl aniline and iodoalkyne derivatives via a gold(I)-catalyzed sequence under visible-light irradiation and in the absence of an exogenous photocatalyst was devised.