Highly Sensitive Formaldehyde Detection Using Well-Aligned Zinc Oxide Nanosheets Synthesized by Chemical Bath Deposition Technique

Abstract

Detection of formaldehyde is very important in terms of life protection, as it can cause serious injury to eyes, skin, mouth and gastrointestinal function if indirectly inhaled. Researchers are therefore putting effort into developing novel and sensitive devices. In this work, we have fabricated an electro-chemical sensor in the form of a field effect transistor (FET) to detect formaldehyde over a wide range (10 nM to 1 mM). For this, ZnO nanosheets (NS) were first synthesized by hydrothermal method with in-situ deposition on cleaned SiO2/Si (100) substrate. The synthesized materials were characterized for morphology and purity and surface area (31.718 m2/g). The developed device was tested for formaldehyde detection at room temperature that resulted in a linear (96%) and reproducible response with concentration, sensitivity value of 0.27 mA/M/cm2 with an error of ±2% and limit of detection (LOD) as 210 nM.

Gas Sensing Technology for the Detection and Early Warning of Battery Thermal Runaway: A Review

“…At present, the commonly used types of gas sensors can be mainly classified as the following: catalytic combustion gas sensor, electrochemical gas sensor, quartz crystal microbalance (QCM) gas sensor, thermal conductive gas sensor, infrared absorption gas sensor, and resistive gas sensor . By summarizing the previous literature, the characteristics of these gas sensors are further quantified and compared as shown in Figure a–f.…”

“…Infrared sensor has been used in battery thermal runaway detection and exhibits high stability, excellent selectivity, and rapid detection speed, but it still has some shortcomings in practical application, such as complex structure, high cost, and difficult integration. Compared with other types of gas sensors, resistive gas sensor exhibits more superiorities such as high sensitivity, high stability, low cost, ease of integration, etc., and has been widely used in the field of thermal runaway gas detection and battery early warning. ,− Although the poor selectivity and high working temperature of resistive gas sensor hinder its wide applications in indoor air detection and medical treatment, they have relatively low impact on the gas detection of battery thermal runaway due to the limited types of released gases and the inherent high-temperature environment during a battery thermal runaway process. On the basis of the above analysis, we will further focus on the resistive gas sensor and its application in the detection and early warning of battery thermal runaway.…”

Inorganic-Diverse Nanostructured Materials for Volatile Organic Compound Sensing

“…High resolution SEM and TEM images of nanosheets are dispayed in Figure 16 . WO 3 clusters decorated In 2 O 3 NShs (synthesized by impregnating method), SnO 2 NShs, ZnO NShs, Au atom dispersed In 2 O 3 NShs, and PdAu bimetal decorated SnO 2 NShs were exploited in the discrimination of HCHO at various operating temperatures [ 263 , 264 , 265 , 266 , 267 ]. However, the ZnO NShs (adopted from hydrothermal method; Figure 16 ) were engaged in aqueous phase detection of HCHO with linear regression of 10 nM to 1 mM and a LOD of 210 nM; thus, it cannot be listed as device-based assays [ 265 ].…”

“…WO 3 clusters decorated In 2 O 3 NShs (synthesized by impregnating method), SnO 2 NShs, ZnO NShs, Au atom dispersed In 2 O 3 NShs, and PdAu bimetal decorated SnO 2 NShs were exploited in the discrimination of HCHO at various operating temperatures [ 263 , 264 , 265 , 266 , 267 ]. However, the ZnO NShs (adopted from hydrothermal method; Figure 16 ) were engaged in aqueous phase detection of HCHO with linear regression of 10 nM to 1 mM and a LOD of 210 nM; thus, it cannot be listed as device-based assays [ 265 ]. Compared to other HCHO sensory reports, Au atom dispersed In 2 O 3 NShs (developed by light assisted reduction method) were highly fascinated with respect to its sensor reposes (R a /R g = 85.67 for 50 ppm at 100 °C; response/recovery time = 25 s/198 s) with an exceptional LOD of 0.00142 ppm [ 266 ].…”

“… Field Emission Scanning Electron Microscopy (FESEM) image ( a ) cross section image ( b ), energy dispersive spectroscopy (EDS) mapping image ( c ) and transmission electron microscope (TEM) image ( d ) (inner HR TEM and selected area diffraction (SAED) pattern) of ZnO NShs (Reproduced with the permission from Ref. [ 265 ]). …”