Enhancing Singlet Oxygen Photocatalysis with Plasmonic Nanoparticles

Abstract

Photocatalysts able to trigger the production of singlet oxygen species are the topic of intense research efforts in organic synthesis. Yet, challenges still exist in improving their activity and optimizing their use. Herein, we exploited the benefits of plasmonic nanoparticles to boost the activity of such photocatalysts via an antenna effect in the visible range. We synthesized silica-coated silver nanoparticles (Ag@SiO 2 NPs), with silica shells which thicknesses ranged from 7 to 45 nm. We showed that they served as plasmonically active supports for tris(bipyridine)ruthenium(II), [Ru(bpy) 3 ] 2+ , and demonstrated an enhanced catalytic activity under white light-emitting diode (LED) irradiation for citronellol oxidation, a key step in the commercial production of rose oxide fragrance. A maximum enhancement of the plasmon-mediated reactivity of approximately 3-fold was observed with a 28 nm silica layer along with a 4-fold enhancement in the emission intensity of the photocatalyst. Using electron energy loss spectroscopy (EELS) and boundary element method simulations, we mapped the decay of the plasmonic signal around the Ag core and provided a rationale for the observed catalytic enhancement. This work provides a systematic analysis of the promising properties of plasmonic NPs used as catalysis-enhancing supports for common homogeneous photocatalysts and a framework for the successful design of such systems in the context of organic transformations.

Dewetted Silver Nanoparticle-Dispersed WO3 Heterojunction Nanostructures on Glass Fibers for Efficient Visible-Light-Active Photocatalysis by Magnetron Sputtering

“…Recently, the mere dispersion of plasmonic metal nanoparticles (such as Ag, Au, Cu, Pt, and Pd) onto a dielectric surface that can radically alter the localized surface plasmon resonance (LSPR) has been considered as the state of the art in the areas of photocatalysis, surface-enhanced Raman scattering, plasmon-enhanced fluorescence, photovoltaics, chemical, and biological sensing applications. , However, fabrication of these nanoparticles with appropriate structure, size, density, and arrangement is crucial as they influence the LSPR phenomenon. To date, chemical synthesis and lithography were reported to fabricate plasmonic metal nanoparticles, , which have limitations such as high cost, complexity in processing, high temperature, reproducibility, and time-consuming.…”

Plasmonic Enhancement Strategies for Light-Driven Microbe Inactivation

“…The initially generated singlet state undergoes a rapid intersystem crossing to generate a long-lived excited triplet state that can form reactive species through multiple pathways . The excited triplet state can be quenched by triplet oxygen ( 3 O 2 ) to form reactive singlet oxygen ( 1 O 2 ), and it is also expected to undergo oxidative and reductive quenching under single electron transfer to form reactive radical species, including the radical superanion O 2 – . The oxidation and reduction potentials of the photoexcited state are E 1/2 ([Ru­(bpy) 3 ] 2+ */[Ru­(bpy) 3 ] 3+ ) = −0.81 V and E 1/2 ([Ru­(bpy) 3 ] 2+ */[Ru­(bpy) 3 ] + ) = +0.77 V (versus saturated calomel electrode (SCE)), respectively, making [Ru­(bpy) 3 ] 2+* both a good oxidant and reductant …”

“…Localization of a photosensitizer in a “sweet spot” where quenching is minimized and excitation rate enhancement is maximized ensures peak performance of the plasmonic photoreactors through optimized plasmonic enhancement of the photosensitizer reactivity . The distance dependence of the reactivity of photosensitizers and photocatalysts bound to a metal NP has been investigated in different systems, and these studies revealed performance gains across a wide separation range from 4–28 nm, depending on the details of the system. ,,− …”

Performances of Homogeneous and Heterogenized Methylene Blue on Silica Under Red Light in Batch and Continuous Flow Photochemical Reactors

“…To counter such sustainability issues, our group and others have developed recyclable photocatalytic systems, such as heterogenized solid PCs (Mori et al, 2010;Mori and Yamashita, 2016;Tambosco et al, 2018;Choi et al, 2020;Gisbertz and Pieber, 2020;Soria-Castro et al, 2020;Materna and Hammarström, 2021). In particular, we investigated the straightforward non-covalent immobilization of PCs on silica particles which resulted in an improved reactivity and stability (Tambosco et al, 2018), and provided additional physical properties such as magnetism (Terra et al, 2020) or plasmonic resonance (Gellé et al, 2021). We also developed a continuous flow photochemical process with a fixed photocatalytic bed reactor to leverage productivity issues (Blanchard et al, 2020).…”