Surface-plasmon-enhanced ultraviolet emission of Au-decorated ZnO structures for gas sensing and photocatalytic devices

Abstract

Pure and Au-decorated sub-micrometer ZnO spheres were successfully grown on glass substrates by simple chemical bath deposition and photoreduction methods. The analysis of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, energy-dispersive X-ray spectroscopy (EDS), UV–vis absorption, and photoluminescence (PL) spectra results were used to verify the incorporation of plasmonic Au nanoparticles (NPs) on the ZnO film. Time-resolved photoluminescence (TRPL) spectra indicated that a surface plasmonic effect exists with a fast rate of charge transfer from Au nanoparticles to the sub-micrometer ZnO sphere, which suggested the strong possibility of the use of the material for the design of efficient catalytic devices. The NO2 sensing ability of as-deposited ZnO films was investigated with different gas concentrations at an optimized sensing temperature of 120 °C. Surface decoration of plasmonic Au nanoparticles provided an enhanced sensitivity (141 times) with improved response (τRes = 9 s) and recovery time (τRec = 39 s). The enhanced gas sensing performance and photocatalytic degradation processes are suggested to be attributed to not only the surface plasmon resonance effect, but also due to a Schottky barrier between plasmonic Au and ZnO structures.

Interactions of Zinc Oxide Nanostructures with Mammalian Cells: Cytotoxicity and Photocatalytic Toxicity

“…It is noticed that the viability of HT 144 cells reduces remarkably by treating with ZnO:Ag(10%) of various concentrations under visible light ( Figure 35 b). The AgNPs dopant facilitates the formation of •O 2− and •OH radicals on ZnO due to the plasmonic oscillation of free electrons under visible light as mentioned previously ( Figure 7 a) [ 69 , 70 , 71 , 72 ]. So, the ROS production efficacy of ZnO:Ag(10%) is considerably higher than that of pure ZnO under visible light illumination.…”

“…This collective electron oscillation causes a charge separation at particle surface with respect to positively charged metallic core ( Figure 6 b) [ 68 ]. SPR absorption induces rapid heating of metal NPs under visible light [ 69 , 70 , 71 ]. So, SPR-generated hot electrons are injected to the CB of ZnO, generating superoxide anion through a surface reaction with adsorbed oxygen, and its subsequent conversion to hydroxyl radical ( Figure 7 a) [ 72 ].…”

“…In recent years, NIR light has been used increasingly in PTT due to minimally invasive cancer treatment [ 73 ]. On the other hand, the role of AuNPs in AuNPs-doped ZnO hybrid is to inject hot electrons into the CB of ZnO for creating ROS under visible light [ 71 , 72 , 77 , 78 ]. The induced ROS are utilized to destroy targeted tumors.…”

Au nanoparticle–decorated ZnO nanorods as fluorescent non-enzymatic glucose probe

“…It was shown that the PL intensity of ZnO NRs at 382 nm can be increased up to 25 times by decoration with Cr NPs [25]. Similarly, a significant PL enhancement was observed followed decoration with Pt, Au and Ag NPs [26][27][28][29].…”

“…The photo-electrons in the conduction band react with O2 to produce a superoxide radical anion O2 -* , while the photogenerated holes in the valence band react with surface hydroxyl ion OHor H2O molecules to produce a OH -* radical. These O2 -* and OH -* radicals are active oxidants, which can oxidize adsorbed molecules such as rhodamine 6G [37,38], rhodamine B [26,39], methylene blue [40], benzene [41]. In studying the photocatalytic oxidation of glucose in water, Cheng et at.…”