Ariadne C. Catto

A novel ozone gas sensor based on one-dimensional (1D) α-Ag2WO4 nanostructures

This paper reports on a new ozone gas sensor based on α-Ag₂WO₄ nanorod-like structures. Electrical resistance measurements proved the efficiency of α-Ag₂WO₄ nanorods, which rendered good sensitivity even for a low ozone concentration (80 ppb), a fast response and a short recovery time at 300 °C, demonstrating great potential for a variety of applications.

An easy method of preparing ozone gas sensors based on ZnO nanorods

One-dimensional (1D) ZnO nanorod-like structures were successfully grown via a hydrothermal method to be used as an ozone gas sensor. X-ray diffraction measurements (XRD) and field-emission scanning electron microscopy (FE-SEM) analysis revealed a preferential growth of the nanorod-like structures along the [002] direction. Electrical resistance measurements indicated a good sensitivity to different ozone concentrations (0.06–1.19 ppm) as well as long-term stability over a 6 month period at 250 °C. In addition, it was observed that the nanorods had a good sensitivity to ozone at room temperature when the sensor was exposed to UV illumination. This study provides an easy and efficient way to obtain 1-D ZnO nanorods exhibiting remarkable properties for applications as ozone gas sensing materials.

Hierarchical growth of ZnO nanorods over SnO2 seed layer: insights into electronic properties from photocatalytic activity

The use of nanostructured heterojunctions has been a promising option for hindering the charge recombination and thus enhancing the photocatalytic performance of catalysts. Here we present a simple strategy to hierarchically grow heterostructures using a hydrothermal treatment route. A buffer SnO2 film was produced by a sol–gel derived method, resulting in a film of approximately 100 nm composed of 5–10 nm nanoparticles. X-ray diffraction and scanning electron microscopy revealed preferential growth of the nanorod-like structures along the c-axis perpendicular to the SnO2 film, with an average nanorod diameter and length of approximately 160 nm and 1.5 μm, respectively. The photoluminescence spectra of ZnO–SnO2 revealed a reduction in UV emission compared to individual ZnO nanorods, indicating that the recombination of the photogenerated carriers was inhibited in the heterojunction. This behavior was confirmed by evaluating the photocatalytic performance of such films against methylene blue degradation, showing that the as-prepared ZnO–SnO2 heterojunction was superior to the individual semiconductors, ZnO and SnO2.

An investigation into the influence of zinc precursor on the microstructural, photoluminescence, and gas-sensing properties of ZnO nanoparticles

This paper describes the effect of different zinc precursors, acetate, oxide, and nitrate, on the structure, microstructure, photoluminescence, and ozone gas-sensing properties of zinc oxide (ZnO) nanoparticles. Transmission and scanning electron microscopy, and BET surface area show a dependence of the particle size and surface area with the precursor type. The ZnO sample synthesized from zinc nitrate shows the best photoluminescence (PL) emission. Although electron paramagnetic resonance shows in all samples the presence of a g-signal attributed to oxygen vacancies, it is not possible to correlate the presence of these defects with PL emission behavior. Furthermore, ZnO sample synthesized from zinc nitrate also shows the best ozone gas-sensing response, however, our results do not allow correlating the best PL emission in the visible region with the best sensor response to ozone gas.