Photoinduced Electrogenerated Chemiluminescence Imaging of Plasmonic Photoelectrochemistry at Single Nanocatalysts

In this study, we proposed a novel imaging technique, photoinduced electrogenerated chemiluminescence microscopy (PECLM), to monitor redox reactions driven by hot carriers on single gold nanoparticles (AuNPs) on TiO₂. Under laser irradiation, plasmon-generated hot carriers were separated by an electric field, leaving hot holes on the surface of AuNPs to drive ECL reactions. PECL intensity was highly sensitive to the number of hot carriers. Through quantitative image analysis, we found that PECL density on individual AuNPs decreased significantly with an increase in particle diameter, indicating that particle size has a significant impact on photoelectrochemical conversion efficiency. For the first time, we verified the feasibility of PECLM in mapping the catalytic activity of single photocatalysts. PECLM opens a new prospect for the in situ imaging of photocatalysis in a high-throughput way, which not only facilitates the optimization of plasmonic photocatalysts but also contributes to the dynamic study of photocatalytic processes on micro/nanointerfaces.

Synthesis of Gold Nanoparticle-Embedded Silver Cubic Mesh Nanostructures Using AgCl Nanocubes for Plasmonic Photocatalysis

A novel room-temperature aqueous synthesis for gold nanoparticle-embedded silver cubic mesh nanostructures using AgCl templates via a template-assisted coreduction method is developed. The cubic AgCl templates are coreduced in the presence of AuCl₄^- and Ag⁺ , resulting in the reduction of AuCl₄^- into gold nanoparticles on the outer region of AgCl templates, followed by the reduction of AgCl and Ag⁺ into silver cubic mesh nanostructures. Removal of the template clearly demonstrates the delicately designed silver mesh nanostructures embedded with gold nanoparticles. The synthetic mechanism, structural properties, and surface functionalization are spectroscopically investigated. The plasmonic photocatalysis of the cubic mesh nanostructures for the degradation of organic pollutants and removal of highly toxic metal ions is investigated; the photocatalytic activity of the cubic mesh nanostructures is superior to those of conventional TiO₂ catalysts and they are catalytically functional even in natural water, owing to their high surface area and excellent chemical stability. The synthetic development presented in this study can be exploited for the highly elaborate, yet, facile design of nanomaterials with outstanding properties.

Aerosol-Sprayed Gold/Ceria Photocatalyst with Superior Plasmonic Hot Electron-Enabled Visible-Light Activity

Integration of nanoscale plasmonic metals with semiconductors is a promising strategy for utilizing visible and near-infrared light to enhance chemical reactions. Here we report on the preparation of Au/CeO₂ microsphere photocatalysts through aerosol spray and the study of their photocatalytic activity toward the aerobic oxidation of 1-phenylethanol under visible light. The microsphere catalysts exhibit a remarkable photocatalytic performance with their turnover frequency values reaching 108 h^-1, which is more than 23 times that of (Au core)@(CeO₂ shell) nanostructures and much larger than those obtained previously for the visible-light photocatalytic oxidation of 1-phenylethanol. In addition, the Au/CeO₂ catalyst shows the best performance among eight types of oxide semiconductor supports. Moreover, the photocatalytic mechanism of the Au/CeO₂ catalyst is systematically investigated. This study offers insights for plasmonic hot electron-enabled photocatalysis, which will be valuable for the design of various efficient (plasmonic metal)/semiconductor photocatalysts.

Size-Dependence of the Activity of Gold Nanoparticle-Loaded Titanium(IV) Oxide Plasmonic Photocatalyst for Water Oxidation

Mesoporous TiO2 nanocrystalline film was formed on fluorine-doped tin oxide electrode (TiO2 /FTO) and gold nanoparticles (NPs) of different sizes were loaded onto the surface with the loading amount kept constant (Au/TiO2 /FTO). Visible-light irradiation (λ>430 nm) of the Au/TiO2 /FTO photoanode in a photoelectrochemical cell with the structure of photoanode|0.1 m NaClO4 aqueous solution|Ag/AgCl (reference electrode)|glassy carbon (cathode) leads to the oxidation of water to oxygen (O2 ). We show that the visible-light activity of the Au/TiO2 /FTO anode increases with a decrease in Au particle size (d) at 2.9≤d≤11.9 nm due to the enhancement of the charge separation and increasing photoelectrocatalytic activity.

Facile synthesis of highly efficient one-dimensional plasmonic photocatalysts through Ag@Cu₂O core-shell heteronanowires

A novel class of one-dimensional (1D) plasmonic Ag@Cu2O core-shell heteronanowires have been synthesized at room temperature for photocatalysis application. The morphology, size, crystal structure and composition of the products were investigated by XRD, SEM, TEM, XPS, and UV-vis instruments. It was found the reaction time and the amount of Ag nanowires play crucial roles in the formation of well-defined 1D Ag@Cu2O core-shell heteronanowires. The resultant 1D Ag@Cu2O NWs exhibit much higher photocatalytic activity toward degradation of organic contaminants than Ag@Cu2O core-shell nanoparticles or pure Cu2O nanospheres under solar light irradiation. The drastic enhancement in photocatalytic activity could be attributed to the surface plasmon resonance and the electron sink effect of the Ag NW cores, and the unique 1D core-shell nanostructure.