Fast humidity sensors based on CeO₂nanowires

Abstract

Fast humidity sensors are reported that are based on CeO2 nanowires synthesized by a hydrothermal method. Both the response and recovery time are about 3 s, and are independent of the humidity. The sensitivity increases gradually as the humidity increases, and is up to 85 at 97% RH. The resistance decreases exponentially with increasing humidity, implying ion-type conductivity as the humidity sensing mechanism. A model based on the morphology and surface energy of the nanowires is given to explain these results further. Our experimental results indicate a pathway to improving the performance of humidity sensors.

Atomic Layer Deposition of Cerium Dioxide Film on TiN and Si Substrates: Structural and Chemical Properties

“…The surface roughness is limited to about 1 nm. On the top of the as-deposited films the absorption of humidity is detected, a well-known phenomenon for CeO2 [17], due to its intrinsic hygroscopicity. The interface roughness is higher in the CeO2/TiN sample than in the CeO2/Si sample and, in addition, a very thin oxidation of TiN surface is detected.…”

Structural, chemical and optical properties of cerium dioxide film prepared by atomic layer deposition on TiN and Si substrates

“…The surface roughness is limited to 1.4 nm. On the top of the as-deposited films the absorption of humidity is detected, a well-known phenomenon for CeO2 [34], due to its intrinsic hygroscopicity. The presence of humidity at the surface has been detected also by performing AFM measurements of the samples, in particular for CeO2/TiN.…”

Hydrothermally synthesized CeO2 nanowires for H2S sensing at room temperature

“…Therefore, it has been widely used in the field of catalyst [1][2][3], photocatalyst [4][5], solid oxide fuel cells [6][7], oxygen pump [9] and luminescence materials [13][14][15]. Recently, CeO2 has also been proposed for one potential sensing material in the field of solid state gas sensors for environmental monitoring, such as CO [16,17], CH4 [17], O2 [18], NO2 [19], carbon disulfide [20] and humidity [21]. Nanostructured CeO2 could significantly enhance the gas sensing performance because of its characteristic structural and electronic properties as mentioned above.…”

“…Nanostructured CeO2 could significantly enhance the gas sensing performance because of its characteristic structural and electronic properties as mentioned above. It is generally accepted that increasing surface area to volume ratio and decreasing crystal sizes of the CeO2 are crucial to achieve a highly sensitive gas sensors [21]. Apart from crystal size, different crystal structures and surface morphologies of the CeO2 nanomaterials could affect their physical and chemical properties and provide new functions for applications.…”