Effect of Nanoparticle Size on Plasmon-Driven Reaction Efficiency

Abstract

Hot electron chemistry is of paramount significance because of its applicability to photocatalytic reactions, solar energy conversion, and waste decomposition. The nonradiative decay of excited plasmons in gold nanoparticles (AuNPs) generates highly energetic nonthermal electrons and holes that can induce chemical reactions when transferred to nearby molecules. In this study, we explore the relationship between AuNP size (26−133 nm) and the plasmoninduced reaction yield. To isolate the size from other structural parameters, we prepare perfectly round gold nanospheres (AuNSs) with narrow size distributions. The use of a nanoparticle-on-mirror configuration, in which the reactant molecules (4-mercaptobenzoic acid) are positioned in nanogaps between the AuNSs and a Au film, promotes the generation of hot carriers and allows the highly sensitive detection of the reaction products (benzenethiol) using surface-enhanced Raman spectroscopy. We show that the reaction yield increases as the AuNS size increases up to 94 nm and then decreases for larger AuNSs. This peculiar Λ-shaped size-dependent reactivity can be explained by considering both the plasmonic absorption efficiency of AuNSs and the decay rate of plasmons via electron-surface scattering. The product of the calculated absorption cross section and the inverse of the AuNS size reproduces our experimental results remarkably well. These findings will contribute to the design of highly efficient plasmonic photocatalysts and photovoltaic devices.

Effect of Nanoparticle Size on Plasmonic Heat‐Driven Organic Transformation

“…For this, the optical density (0.4) at the surface plasmon band of each AuNPs was normalized for a fair comparison of the size effect, which is a commonly used normalization strategy. [11] The broad emission peak of LEDs (� 40 nm) will take care of the difference in the λ max position of different sizes of AuNPs. The time of irradiation was reduced to 75 min in order to accommodate for the higher yield that may be obtained with different sizes of AuNPs.…”

“…This essentially means that the scattering cross-section will keep on increasing as a function of NP size; whereas the absorption cross-section will reach a plateau at a particular size regime. [11] Likewise, the heat dissipation step is related to the size of the AuNPs. It has been shown that the rate of heat dissipation decreases with an increase in NP size, because of the higher heat capacity for larger NPs.…”

“…Furthermore, this pyrone to pyridinone transformation was used as a tool to study the influence of AuNP size on the generation, dissipation, and utilization of plasmonic heat. The size effect was studied by normalizing the optical density at the surface plasmon band of each AuNPs [11] . It is predicted that the scattering cross‐section as well as the heat capacity of AuNPs increases with size, both of which are crucial factors in the plasmonic heat generation and dissipation steps [11,12] .…”

“…[11] It is predicted that the scattering cross-section as well as the heat capacity of AuNPs increases with size, both of which are crucial factors in the plasmonic heat generation and dissipation steps. [11,12] Thus, there should be an optimal size range where the chemical effectiveness of the plasmonic heat from AuNPs is maximum. Such trends have been observed previously for iron oxide NPs during the decomposition of poly(propylene carbonate) (PPC).…”

Observation of domain‐selective defect effects from a CVD‐grown graphene monolayer sandwiched at individual nanoparticle‐on‐mirror plasmonic junctions

“…[11] Fang and co-workers previously examined the emission effect of photoexcited hot electrons from plasmonic metal nanostructure, which is still a challenging issue in the field of nanophotonics for solar harvesting, water splitting, photocatalysis, and a variety of optical sensing. [12] In this work, the investigation of spaced CVD-GM in NPoM for the locational relationship by loading individual Au nanoparticles (NPs) likewise seminanoindentation through the AFM topography with corresponding Raman image (and SERS spectral behaviors) is carried out and discovered the domain-dependent (the most outer/center domain) different defect types phenomena in the NPoM system [13][14][15][16][17][18][19][20][21][22][23][24] in terms of establishing the new defect domain-selective sensing platform. The individual NPoM plasmonic junction, composed of Au NP/CVD-GM /Au TF, can be precisely inspected by AFM, and the author can find out that the line profile of the most outer domain of NPoM shows near-two symmetrical deep pits, due to probably physical loading of Au NP onto the CVD-GM/Au TF.…”