Thermal and Nonthermal Effects in Plasmon-Mediated Electrochemistry at Nanostructured Ag Electrodes

Hot carriers (HCs) and thermal effects, stemming from plasmon decays, are crucial for most plasmonic applications. However, quantifying these two effects remains extremely challenging due to the experimental difficulty in accurately measuring the temperature at reaction sites. Herein, we provide a novel strategy to disentangle HCs from photothermal effects based on the different traits of heat dissipation (long range) and HCs transport (short range), and quantitatively uncover the dominant and potential-dependent role of photothermal effect by investigating the rapid- and slow-response currents in plasmon-mediated electrochemistry at nanostructured Ag electrode. Furthermore, the plasmoelectric surface potential is found to contribute to the rapid-response currents, which is absent in the previous studies.     

Identification of Nanoparticles via Plasmonic Scattering Interferometry

The development of optical imaging techniques has led to significant advancements in single‐nanoparticle tracking and analysis, but these techniques are incapable of label‐free selective nanoparticle recognition. A label‐free plasmonic imaging technology that is able to identify different kinds of nanoparticles in water is now presented. It quantifies the plasmonic interferometric scattering patterns of nanoparticles and establishes relationships among the refractive index, particle size, and pattern both numerically and experimentally. Using this approach, metallic and metallic oxide particles with different radii were distinguished without any calibration. The ability to optically identify and size different kinds of nanoparticles can provide a promising platform for investigating nanoparticles in complex environments to facilitate nanoscience studies, such as single‐nanoparticle catalysis and nanoparticle‐based drug delivery.     

Synergy between Plasmonic and Electrocatalytic Activation of Methanol Oxidation on Palladium–Silver Alloy Nanotubes

Localized surface plasmon resonance (LSPR) excitation of noble metal nanoparticles has been shown to accelerate and drive photochemical reactions. Here, LSPR excitation is shown to enhance the electrocatalysis of a fuel‐cell‐relevant reaction. The electrocatalyst consists of Pd_xAg alloy nanotubes (NTs), which combine the catalytic activity of Pd toward the methanol oxidation reaction (MOR) and the visible‐light plasmonic response of Ag. The alloy electrocatalyst exhibits enhanced MOR activity under LSPR excitation with significantly higher current densities and a shift to more positive potentials. The modulation of MOR activity is ascribed primarily to hot holes generated by LSPR excitation of the Pd_xAg NTs.     

The Fundamentals of Real‐Time Surface Plasmon Resonance/Electrogenerated Chemiluminescence

We report the integration of surface plasmon resonance (SPR), cyclic voltammetry and electrochemiluminescence (ECL) responses to survey the interfacial adsorption and energy transfer processes involved in ECL on a plasmonic substrate. It was observed that a Tween 80/tripropylamine nonionic layer formed on the gold electrode of the SPR sensor, while enhancing the ECL emission process, affects the electron transfer process to the luminophore, Ru(bpy)₃²⁺, which in turn has an impact on the plasmon resonance. Concomitantly, the surface plasmon modulated the ECL intensity, which decreased by about 40 %, due to an interaction between the excited state of Ru(bpy)₃²⁺ and the plasmon. This occurred only when the plasmon was excited, demonstrating that the optically excited surface plasmon leads to lower plasmon‐mediated luminescence and that the plasmon interacts with the excited state of Ru(bpy)₃²⁺ within a very thin layer.     

Reversible Size Control of Liquid‐Metal Nanoparticles under Ultrasonication

This paper describes the reversible control of the size of liquid‐metal nanoparticles under ultrasonication. Gallium was utilized as a liquid metal, which has a melting point of 29.8 °C. Investigating the effects of ultrasonication (power, time, and temperature) on the formation of gallium nanoparticles revealed that the process is similar to the formation of oil in water (O/W) or water in oil (W/O) emulsions, as the temperature significantly affects the size of the gallium nanoparticles (GaNPs). Under ultrasonication, the balance between the break‐up and coalescence of the GaNPs can be adjusted by changing the temperature or adding acid through modulating the natural surface oxide layer (which can be removed with acid) and the stabilizing effect of the surfactant dodecanethiol. Coalescence was predominant at higher temperatures, whereas particle break‐up was found to be predominant at lower temperatures. Furthermore, the change in size was accompanied by a shift in the plasmonic absorption of the GaNPs in the UV region.