How Chemoresistive Sensors Can Learn from Heterogeneous Catalysis. Hints, Issues, and Perspectives

Monter-Guzmán, Jessica Yazmín Monter; Chu, Xiangcheng; Comini, Elisabetta; Epifani, Mauro; Zanella, Rodolfo

doi:10.3390/chemosensors9080193

Cited by 6 publications

(5 citation statements)

References 205 publications

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“…The temperature also plays an important role here in fetching the required activation energy of the catalytic reaction. Similar oxidation reactions are seen for gases like NO 2 , SO 2 , CO, H 2 S, etc [54].…”

Section: Ac Sensing Responsesupporting

confidence: 60%

“…For instance, the oxide nanoparticles are usually used as a catalytic material which makes the adsorbed gas molecule undergo a catalytic oxidation or reduction reaction. This is mostly the case for volatile organic compounds such as acetone, alcohols, aromatic compounds etc [54]. Therefore, the initial interaction is strongly governed by the catalytic properties of oxides and is often improved with the addition of noble metal catalyst particles.…”

Section: Ac Sensing Responsementioning

confidence: 99%

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Frequency dependent impedance response analysis of nanocrystalline ZnO chemiresistors

P V,

Tom,

Urs

et al. 2023

Nanotechnology

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ZnO is a widely studied gas sensor material and is used in many commercial sensor devices. However, selectivity towards any particular gas remains an issue due to a lack of complete knowledge of the gas sensing mechanism of oxide surfaces. In this paper, we have studied the frequency dependent gas sensor response of ZnO nanoparticles of a diameter of nearly 30 nm. A small rise of synthesis temperature from 85 to 95oC in the solvothermal process, shows coarsening by joining and thereby distinct loss of grain boundaries as seen from transmission electron micrographs. This leads to a substantial reduction in impedance, Z (GΩ to MΩ), and rises in resonance frequency fres (from 1 to 10 Hz) at room temperature. From temperature dependent studies it is observed that the grain boundaries show a Correlated Barrier Hopping (CBH) mechanism of transport and the hopping range in the grain boundary region is typically 1 nm with a hopping energy of 153 meV. On the other hand, within the grain, it shows a change of transport type from low temperature tunneling to beyond 300oC as polaron hopping. The presence of disorder (defects) as the hopping sites. The temperature dependence of fres agrees with different predicted oxygen chemisorbed species between 200 to 400oC. As opposed to the traditional DC response, the AC response in the imaginary part of Z (Z′′) shows gas specific resonance frequencies for each gas, such as NO2, ethanol, and H2. Among the two reducing gases, ethanol and hydrogen; the former shows good dependence on concentration in Z′′ whereas the latter shows a good response in fres as well as capacitance. Thus, the results of frequency dependent response allow us to investigate greater details of the gas sensing mechanism in ZnO, which may be exploited for selective gas sensing.

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Section: Ac Sensing Responsesupporting

confidence: 60%

Section: Ac Sensing Responsementioning

confidence: 99%

Frequency dependent impedance response analysis of nanocrystalline ZnO chemiresistors

P V,

Tom,

Urs

et al. 2023

Nanotechnology

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“…The catalytic properties of reduced tungsten oxides were established several years ago [ 133 ]. An important feature of WO 3 surfaces is the presence of strong Lewis sites, which play an essential role in the adsorption of a gaseous species in catalysis and, therefore, are of paramount importance for sensors as well [ 134 ].…”

Section: Wo 3 Structures and Surfacesmentioning

confidence: 99%

Mechanistic Insights into WO3 Sensing and Related Perspectives

Epifani

2022

Sensors

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Tungsten trioxide (WO3) is taking on an increasing level of importance as an active material for chemoresistive sensors. However, many different issues have to be considered when trying to understand the sensing properties of WO3 in order to rationally design sensing devices. In this review, several key points are critically summarized. After a quick review of the sensing results, showing the most timely trends, the complex system of crystallographic WO3 phase transitions is considered, with reference to the phases possibly involved in gas sensing. Appropriate attention is given to related investigations of first principles, since they have been shown to be a solid support for understanding the physical properties of crucially important systems. Then, the surface properties of WO3 are considered from both an experimental and first principles point of view, with reference to the paramount importance of oxygen vacancies. Finally, the few investigations of the sensing mechanisms of WO3 are discussed, showing a promising convergence between the proposed hypotheses and several experimental and theoretical studies presented in the previous sections.

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“…, catalytic combustion gas sensors, 12 electrochemical gas sensors, 13 infrared absorption gas sensors 14 and resistive gas sensors. 15–17 Among them, the resistive gas sensor exhibits attractive advantages, including higher sensitivity, faster response/recovery times, greater stability/repeatability, ease of operation and integration into portable devices. 18–20 Based on these advantages, the resistive gas sensor has been widely studied and occupies a large market share.…”

Section: Introductionmentioning

confidence: 99%