Humidity-Tolerant Ultrathin NiO Gas-Sensing Films

Abstract

When the gas sensor active layer film thickness is decreased increased sensitivity to changes in the adsorbate concentration are expected when measuring the resistance of the layer, in particular when this thickness is on the order of the Debye length of the material (one to tens of nanometers), however this is demonstrated only for a limited number of materials. Herein, ultra-thin NiO films of different thickness (8 to 21 nm) have been deposited via chemical vapour deposition to fabricate gas sensor devices. Sensor performance toward a range of NO2 concentration (800 part-per-billion to 7 part-per-million) was evaluated and an optimum operating temperature of 125°C determined.The dependence of the potential relative changes with respect to the NO2 concentration and of the sensor signal with respect to the geometrical parameters were qualitatively evaluated in order to derive a transduction model capable to fit the experimental results. The selective sensitivity towards NO2 was confirmed by the limited response for different reducing gases, CO, CH4, NH3 and SO2 under optimum operating conditions, and the sensor signal towards NO2 increased with decreasing thickness, demonstrating that the concept of a Debye length dependence of sensitivity is applicable for the p-type semiconductor NiO. In addition, these NiO sensors were exposed to different relative levels of humidity over a wide range of operating temperatures and found to display humidity tolerance far superior to previous reports for SnO2 materials.

CQDs@NiO: An Efficient Tool for CH4 Sensing

“…Recently, nanocrystalline NiO nanoplates [29], porous NiO nanosheets [30], and Pt@NiO core-shell nanostructure [31] were employed in hydrogen sensing. Selective sensitivity toward NO 2 in a humid environment was confirmed by the limited response for different reducing gases, such as CO, CH 4 , NH 3 , and SO 2 , using ultrathin NiO sensors [32]. Acetone could be detected using Ru-doped NiO [33] or NiFe 2 O 4 nanoparticle-decorated NiO nanosheet sensors [34].…”

Research Progress on Coating of Sensitive Materials for Micro-Hotplate Gas Sensor

“…Under the optimal working temperature of 125 °C, NO 2 detection is realized. The test results show that the response signal of the sensor to NO 2 increases with the decrease of the thickness of NiO, which proves that the dependence of sensor sensitivity on Debye length applies to NiO [ 68 ].…”

Enhanced Blocking Effect: A New Strategy to Improve the NO2 Sensing Performance of Ti3C2Tx by γ-Poly(l-glutamic acid) Modification

“…40 The influence of humidity on the gas sensor is a serious and universal problem in practical applications. There are three typical methods to reduce humidity interference as follows: (i) using a dehumidifier to pretreat the target gas before testing, 41 (ii) using hydrophobic-material modification or a bionic hydrophobic-structure design to enhance the humidity tolerance of the sensing materials, 42 and (iii) considering the sensor array and advanced data processing, the humidity compensation model is established to minimize cross-effects. 43 In this work, a practical method to solve this problem is presented in data processing.…”