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Monitoring plasmonic hot-carrier chemical reactions at the single particle level
摘要： Plasmon excitation in metal nanoparticles triggers the generation of highly energetic charge carriers that - properly manipulated and exploited - can mediate chemical reactions. Single-particle techniques are key to unearth the underlying mechanisms of hot-carrier generation, transport and injection as well as to disentangle the role of the temperature increase and the enhanced near-field at the nanoparticle-molecule interface. Gaining a nanoscopic insight of these processes and their interplay could aid in the rational design of plasmonic photocatalysts. Here, we present three different approaches to monitor hot-carrier reactivity at the single-particle level. We use a combination of dark-field microscopy and photo-electrochemistry to track a hot-hole driven reaction on a single Au nanoparticle. We image hot-electron reactivity with sub-particle spatial resolution using nanoscopy techniques. Finally, we push the limits looking for a hot-electron induced chemical reaction that generates a fluorescent product, which should enable imaging of active plasmonic photocatalysis at the single-particle and single-molecule levels.
关键词： dark-field microscopy,fluorescent product,single-particle techniques,Plasmonic hot-carriers,plasmonic photocatalysis,photo-electrochemistry,nanoscopy techniques
更新于2025-11-19 16:56:42
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Visible-Light Plasmonic Enhancement of Catalytic Activity of Anisotropic Silver Nanoparticles
摘要： Synthesis of silver nanoparticles (AgNPs) in presence of copper salt (as the etchant) led to the formation of nanoparticle samples with different fractions of anisotropic particles. The proportion of anisotropic nanoparticles decreased with increase in ratio of precursor Cu salt in the preparation protocol. These AgNPs samples were found to catalyse p-nitrophenol reduction by glycerol and Fenton oxidation of methyl orange. The catalytic activity of these AgNPs samples for these reactions increased with the fraction of anisotropic nanoparticles in the catalyst samples. On conducting these reactions under cool white LED visible light, the catalytic activity of AgNPs catalyst samples increased by 2 to 3 times compared to that observed in dark. The photo-Fenton MO degradation catalytic activity obtained is among the best reported in literature. However, the order of the reaction did not change whether the reaction was conducted under visible light or in dark. Direct plasmonic catalytic mechanisms are proposed to explain the enhancement in reactivity under visible light.
关键词： Plasmonic Photocatalysis,Visible Light,Anisotropic Silver Nanoparticles
更新于2025-11-19 16:56:42
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Synthesis and characterization of Bi-BiPO4 nanocomposites as plasmonic photocatalysts for oxidative NO removal
摘要： Bi metal–BiPO4 (Bi-BPO) nanocomposites formed by in situ solvothermal reduction were employed as plasmonic photocatalysts for oxidative NO removal, achieving a removal efficiency of 32.8% in a continuous NO flow (400 ppb) under illumination with visible light. This high performance was ascribed to the generation of energetic hot electrons (and their subsequent surface chemical reactions) due to the surface plasmon resonance (SPR) of Bi metal, as validated by numerical simulations. The combined results of density functional theory (DFT) calculations and electrochemical analysis revealed that hot electrons are transferred from Bi metal to BPO via the Bi-BPO interface. DFT calculations further showed that enhanced O2 activation on the Bi-BPO interface facilitates the generation of both superoxide (?O2?) and hydroxyl (?OH) radicals, as confirmed by electron spin resonance, while in situ DRIFTS analysis demonstrated that NO is activated on the Bi-BPO interface and then oxidized to nitrates. Thus, this work highlights the SPR effects of Bi metal and promoted O2 and NO activation in plasmonic photocatalysis, showing that the adopted approach can be generalized to design efficient and cost-effective photocatalytic systems for the removal of other gaseous pollutants.
关键词： Bi metal,O2 and NO activation,NO removal,plasmonic photocatalysis
更新于2025-09-23 15:19:57
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Plasmonic photocatalysis applied to solar fuels
摘要： The induction of chemical processes by plasmonic systems is a rapidly growing field with potentially many strategic applications. One of them is the transformation of solar energy into chemical fuel by the association of plasmonic metal nanoparticles (M NPs) and a semi-conductor (SC). When the localized surface plasmon resonance (LSPR) and the SC absorption do not match, one limitation of these systems is the efficiency of hot electron transfer from M NPs to SC through the Schottky barrier formed at the M NPs/SC interfaces. Here we show that high surface area 1wt.%Au/TiO2-UV100, prepared by adsorption of a NaBH4-protected 3 nm gold sol, readily catalyzes the photoreduction of carbon dioxide with water into methane under both solar and visible-only irradiations with a CH4 vs. H2 selectivity of 63%. Tuning Au NPs size and titania surface area, in particular via thermal treatments, highlights the key role of the metal dispersion and of the accessible Au-TiO2 perimeter interface on the direct SC-based solar process. The impact of Au NPs density in turn evidences the dual role of gold as co-catalyst and recombination sites for charge carriers. It is shown that the plasmon-induced process contributes up to 20% of the solar activity. The plasmon-based contribution is enhanced by a large Au NP size and a high degree of crystallinity of the SC support. By minimizing surface hydroxylation while retaining a relatively high surface area of 120 m2 g-1, pre-calcining TiO2-UV100 at 450°C leads to an optimum monometallic system in terms of activity and selectivity under both solar and visible irradiation. A state-of-the-art methane selectivity of 100% is achieved in the hot electron process.
关键词： Methane production,Gold nanoparticles,Titania,Selectivity,CO2 reduction,Hot electrons,Plasmonic photocatalysis,Solar fuels
更新于2025-09-19 17:15:36
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Taking the Heat Off of Plasmonic Chemistry
摘要： Plasmon-excitation-mediated chemistry, which is a rapidly growing field, is founded on a simple principle: the excitation of the localized surface plasmon resonance (LSPR) of metal nanoparticles triggers chemical reactions on the surfaces of the nanoparticles. Early examples of plasmon-excitation-driven nanoparticle synthesis and hot-electron-driven chemical reactions induced by ultrashort pulse excitation of metal nanoparticles can be thought of as precursors to the findings of direct photocatalysis by plasmonic nanoparticles, which is the focus of this Viewpoint. The field in its current state was, in large part, invigorated by a 2011 paper, which showed that the excitation of the LSPR of Ag nanoparticles by continuous-wave (CW), visible-frequency light triggered the dissociation of adsorbed O2. The O· atoms thus produced were utilized for industrially relevant oxidation reactions such as those of propylene and ethylene, which would have otherwise required high-temperature and -pressure conditions to proceed at appreciable rates. In the absence of visible-light excitation, the bond dissociation and oxidation reactions proceeded at appreciably low rates, which indicated that plasmonic excitation enhanced the rates of these chemical reactions. The phenomenon is, therefore, termed as plasmonic catalysis or plasmonic photocatalysis.
关键词： Plasmonic catalysis,Plasmonic photocatalysis,Chemical reactions,Hot electrons,Photothermal heating
更新于2025-09-16 10:30:52
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Plasmonic oxidation of glycerol using AuPd/TiO2 catalysts
摘要： AuPd nanoparticles supported on P25 TiO2 (AuPd/TiO2) were prepared by a facile sol-immobilisation method and investigated for surface plasmon-assisted glycerol oxidation under base-free conditions. The AuPd/TiO2 samples were characterized by UV-vis spectroscopy and transmission electron microscopy. The sol-immobilisation method readily permitted the Au:Pd molar ratio to be changed over a wide range whilst keeping the mean particle size of the AuPd nanoparticles at 3nm. Visible light irradiation during the reaction has a beneficial effect on the conversion of glycerol with the most marked effect being observed with gold-rich catalysts and the increase of conversion on light irradiation increases linearly with the gold content of the nanoparticles. The reaction selectivity is also affected by the plasmon-assisted oxidation and glycolic acid, not observed during the dark reactions, was observed for all illuminated reactions due to the enhanced activity of these catalysts.
关键词： visible light irradiation,AuPd nanoparticles,glycerol oxidation,plasmonic photocatalysis,sol-immobilisation
更新于2025-09-11 14:15:04
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Influence of Semiconductor Morphology on Photocatalytic Activity of Plasmonic Photocatalysts: Titanate Nanowires and Octahedral Anatase Nanoparticles
摘要： Octahedral anatase particles (OAP) with eight exposed and thermodynamically most stable (101) facets were prepared by an ultrasonication-hydrothermal (US-HT) reaction from potassium titanate nanowires (TNW). The precursor (TNW) and the product (OAP) of US-HT reaction were modi?ed with nanoparticles of noble metals (Au, Ag or Pt) by photodeposition. Samples were characterized by X-ray di?raction (XRD), X-ray photoelectron spectroscopy (XPS), di?use re?ectance spectroscopy (DRS), scanning transmission electron microscopy (STEM) and time-resolved microwave conductivity (TRMC). The photocatalytic activity was investigated in three reaction systems, i.e., anaerobic dehydrogenation of methanol and oxidative decomposition of acetic acid under UV/vis irradiation, and oxidation of 2-propanol under vis irradiation. It was found that hydrogen liberation correlated with work function of metals, and thus the most active were platinum-modi?ed samples. Photocatalytic activities of bare and modi?ed OAP samples were much higher than those of TNW samples, probably due to anatase presence, higher crystallinity and electron mobility in faceted NPs. Interestingly, noble metals showed di?erent in?uence on the activity depending on the semiconductor support, i.e., gold-modi?ed TNW and platinum-modi?ed OAP exhibited the highest activity for acetic acid decomposition, whereas silver- and gold-modi?ed samples were the most active under vis irradiation, respectively. It is proposed that the form of noble metal (metallic vs. oxidized) as well as the morphology (well-organized vs. uncontrolled) have a critical e?ect on the overall photocatalytic performance. TRMC analysis con?rmed that fast electron transfer to noble metal is a key factor for UV activity. It is proposed that the e?ciency of plasmonic photocatalysis (under vis irradiation) depends on the oxidation form of metal (zero-valent preferable), photoabsorption properties (broad localized surface plasmon resonance (LSPR)), kind of metal (silver) and counteraction of “hot” electrons back transfer to noble metal NPs (by controlled morphology and high crystallinity).
关键词： silver,platinum,gold,photocatalyst morphology,faceted titania,morphology-governed activity,plasmonic photocatalysis,octahedral particle,titanate nanowire,noble metal
更新于2025-09-11 14:15:04
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Selective growth of palladium nanocrystals on the (100) facets of truncated octahedral Cu <sub/>2</sub> O for UV plasmonic photocatalysis
摘要： We report Pd-based UV plasmon-enhanced photocatalysis and its hot electron effect. The selective crystalline growth of Pd nanocrystals on the (100) facets of truncated octahedral Cu2O was conducted and proved. The photocatalytic activities of Pd/Cu2O at λ = 254 nm and at λ = 365 nm respectively had ca. 18- and 10-fold enhancements due to the hot electron effect.
关键词： palladium nanocrystals,UV plasmonic photocatalysis,hot electron effect,Cu2O
更新于2025-09-04 15:30:14