High Sensitivity of NO Gas Sensors Based on Novel Ag-Doped ZnO Nanoflowers Enhanced with a UV Light-Emitting Diode

Abstract

An ultraviolet-enhanced (UV-enhanced) nitric oxide (NO) sensor based on silver-doped zinc oxide (ZnO) nanoflowers is developed using a low-cost hydrothermal method. The results indicate that silver (Ag) ions were doped into the ZnO nanostructure successfully, thus changing the morphology. In the high-resolution transmission electron microscopy images, we also found that some Ag ions were separated out onto the surface of the ZnO nanoflowers and that the Ag-doped and Ag nanoparticles improved the sensing property. The NO sensing property increased from 73.91 to 89.04% through the use of a UV light-emitting diode (UV-LED). The response time was approximately 120 s without the UV-LED, and the UV-enhanced Ag-doped ZnO nanoflower sensor exhibited a reduced response time (60 s). The best working temperature could be reduced from 200 to 150 °C using UV light illumination, and it was found that the NO response increased by 15.13% at 150 °C. The UV photoresponse of the Ag-doped ZnO nanoflowers and the mechanisms by which the improvement of NO sensing property occurred through the use of UV light illumination are discussed. The property of the gas sensor can be calibrated using a self-photoelectric effect under UV light illumination. These interesting UV-enhanced Ag-doped ZnO nanoflowers are viable candidates for practical applications.

Silver Nanoparticles as Colorimetric Sensors for Water Pollutants

“…On the other hand, the void area has been used to tune the refractive index, increase the active region for catalysis, and advance the ability to tolerate cyclic volume modifications. The morphology plays a key role, especially for the possibility of having materials with different symmetries (spheres, AgNPs, cubes AgNCs) [79][80][81][82][83][84][85][86][87] or without defined and reproducible symmetry (stars, AgNSs, flower, AgNFs, wires, AgNWs) [69,[88][89][90][91][92][93][94]. TEM images of silver nanoparticles of different geometries and shape are presented in Figure 4.…”

Liquid Metal-Based Epidermal Flexible Sensor for Wireless Breath Monitoring and Diagnosis Enabled by Highly Sensitive SnS 2 Nanosheets

“…The device exhibited a 197% sensitivity to 200 ppb with a response time of 223 s and easily recovered its initial resistance once we had stopped injecting NO. In contrast to most other NO sensors, our LM-based electrode performed rather well at low concentrations and could detect NO levels as low as 15 ppb with a sensitivity of 8.7% [45][46][47][48][49][50][51][52][53][54]. The sensitivity of our sensor exhibits a strong linear correlation with the gas concentration (Figure 3(c), R 2 = 0:95).…”

Advances in Doped ZnO Nanostructures for Gas Sensor

“…[7] It is widely used in the fields of solar cells, [8] light-emitting diodes, [9] piezoelectric devices [10] and gas sensors. [11] As wurtzite crystal, ZnO has three rapid growth directions, which leads to the diversity of its morphology, such as: nanosheet, nanoparticle, nanorod, nanowire, macroporous honeycomb-like, core-shell microspheres etc. [5,12a,b,c,d,e] In addition, ZnO exhibits excellent physical and chemical stability, which is important for practical sensing material.…”

“…Among them, ZnO is an important multi‐functional n‐type semiconductor material with a wide band gap of 3.37 eV, a large exciton binding energy of 60 meV and a high hall mobility of 200 cm 2 v −1 s −1 at room temperature [7] . It is widely used in the fields of solar cells, [8] light‐emitting diodes, [9] piezoelectric devices [10] and gas sensors [11] . As wurtzite crystal, ZnO has three rapid growth directions, which leads to the diversity of its morphology, such as: nanosheet, nanoparticle, nanorod, nanowire, macroporous honeycomb‐like, core‐shell microspheres etc [5,12a,b,c,d,e] .…”