Plasmonic photocatalysis in aqueous solution: assessing the contribution of thermal effects and evaluating the role of photogenerated ROS

Abstract

Plasmon-induced photocatalysis can drive photochemical processes with an unprecedented control of reactivity, using light as sole energy source. Nevertheless, disentangling the relative importance of thermal and non-thermal features upon plasmonic...

Plasmonics: A Versatile Toolbox for Heterogeneous Photocatalysis

“…Negrín‐Montecelo and coworkers have used a colloidal Au‐TiO 2 hybrid photocatalyst for the plasmonic photo‐oxidation of a model organic substrate in water. [ 67 ] This study demonstrates the presence of all four major ROS in the reaction medium upon plasmonic excitation, given the interaction between the photogenerated hot holes in the metal and the hot electrons injected into the conduction band of the semiconductor with water and oxygen molecules ( Figure ). Importantly, the authors demonstrate that the •OH species generated at the photoanode (below the Fermi level of the metal) is the main intermediate responsible for the photo‐oxidation of the organic molecule.…”

“…Under continuous illumination and without any convection favoring heat transfer out from the NP into the surrounding medium, the object and its close vicinity end up reaching a steady-state temperature that is higher than the temperature of the bulk medium. [67,68] Such focalized heat dissipation is used in photothermal therapy (also called plasmonic hyperthermia) for cancer treatment, to locally target cancer cells without damaging healthy tissues. [69,70] Similarly, this localized heat can induce and accelerate reactions under overall milder thermal conditions than conventional thermal catalysis.…”

“…Such methods give access to light propagation and heat transfer processes under the given experimental conditions. [67,72] Kamarudheen and colleagues took advantage of both experimental and theoretical approaches to quantify photothermal and nonthermal effects in the temperature-sensitive synthesis of core-shell Au@Ag NPs under irradiation. [72] The authors quantified the growth rate of the Ag shell by monitoring the change in the extinction spectra of Au NPs in the dark under heating and under plasmon excitation without any external heating.…”

“…Several reports have shown that it is possible to generate the four main ROS presented above by simply irradiating a plasmonic photocatalyst in aqueous solution. [67,196,197] In most cases, ROS are detected and quantified by means of electron spin resonance spectroscopy (ESR) or through the use of molecular scavengers that react selectively with each one of them. Negrín-Montecelo and coworkers have used a colloidal Au-TiO 2 hybrid photocatalyst for the plasmonic photo-oxidation of a model organic substrate in water.…”

Influence of plasmons on the luminescence properties of solvatochromic merocyanine dyes with different solvatochromism

“…Improvements of the light conversion in photocatalytic and photovoltaic systems can be obtained by a direct transfer of hot charge carriers [21][22][23] and by increasing the absorption rate constant of photons by the reactant molecules due to the optical amplification of the local electromagnetic field at the NP surface. 24,25 These properties are used to increase the rate of chemical reactions such as water splitting, 25,26 CO 2 recovery and utilization, 27 photodegradation of organic compounds [28][29][30] as well as to increase the efficiency of photocatalytic materials 25,31,32 and solar cells. [33][34][35][36][37] Applications of the plasmonic effect in optical technologies, where fluorophore molecules at the surface of metallic NPs are exposed to local electromagnetic fields (Fig.…”