Flower-Like ZnO Nanostructure for NO Sensing at Room Temperature

Chang, Wei‐Chen; Yu, Wan-Chin; Wu, Chung-Yu; Wang, Chenyang; Hong, Zih-Siou; Wu, Ren‐Jang

doi:10.1166/jnn.2016.12892

Cited by 5 publications

(5 citation statements)

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“…In this study, because the optimal T w is approximately 90 °C, the dominant oxygen species is considered to be O 2(ads) – . Normally, when the sensing materials are exposed to NO, the increase of the resistance in the ZnO nanoparticles (n-type) and the decrease of the resistance in the N-rGO or rGO (p-type in our experiments) are expected. The details of adsorption and the reaction process between NO and O 2(ads) – are listed in eqs and .…”

Section: Gas-sensing Properties and Potential Mechanismsmentioning

confidence: 73%

“…In this study, because the optimal T w is approximately 90 °C, the dominant oxygen species is considered to be O 2(ads) − . Normally, when the sensing materials are exposed to NO, the increase of the resistance in the ZnO nanoparticles (n-type) 56 O 2(ads) − are listed in eqs 4 and 5. Also, as shown in eq 8, when H 2 , a reducing gas meets the sensing material, an opposite electrontransfer process and phenomenon, that is, a decrease in resistance for ZnO nanoparticles and an increase in resistance for N-rGO or rGO are anticipated.…”

Section: Resultsmentioning

confidence: 99%

“…The reason why the difference between S H 2 (air) and S H 2 (N 2 ) is faint is may be because S H 2 (air) itself is very small, which results from the relatively small adsorption energy of H 2 on N-rGO and ZnO nanoparticles. 13,55,56 5. CONCLUSIONS In summary, a hybrid nanomaterial of ZnO nanocrystals well anchored on nitrogen-doped reduced graphene oxide (NGZ-0.3) was successfully synthesized through a facile two-step hydrothermal process by adjusting the quantity of NH 4 OH as the nitrogen source.…”

Section: Resultsmentioning

confidence: 99%

“…Actually, for the sensitivity of the sensor to H 2 under different background gases of air and N 2 , S H 2 (air) should be less than the S H 2 (N 2 ) under the same principle, which is consistent with the trend shown by experiment. The reason why the difference between S H 2 (air) and S H 2 (N 2 ) is faint is may be because S H 2 (air) itself is very small, which results from the relatively small adsorption energy of H 2 on N-rGO and ZnO nanoparticles. ,, …”

Section: Gas-sensing Properties and Potential Mechanismsmentioning

confidence: 99%

See 3 more Smart Citations

Observation of Switchable Dual-Conductive Channels and Related Nitric Oxide Gas-Sensing Properties in the N-rGO/ZnO Heterogeneous Structure

Qiu

Min

et al. 2020

ACS Appl. Mater. Interfaces

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Gas sensors based on hybrid materials of graphene oxide/metal oxide semiconductors are an effective way to improve sensor performance. In this paper, we demonstrate a high-performance nitric oxide (NO) gas sensor based on nitrogen-doped reduced graphene oxide/ZnO nanocrystals (N-rGO/ZnO) operating at a low work temperature. ZnO nanocrystals, with an average size of approximately 5 nm, can be uniformly and compactly anchored on the surface of N-rGO using a facile two-step hydrothermal synthesis with an appropriate amount of ammonia as the nitrogen source. The sensor based on the N-rGO/ZnO composite with 0.3 mL of ammonia (N-rGO/ZnO-0.3), in comparison with N-rGO/ZnO with different amounts of ammonia, N-rGO, and rGO/ZnO, exhibited a significantly higher sensitivity (S = R g/R a) at the parts per billion (ppb) level for NO gas at 90 °C. The maximum sensitivity at 800 ppb NO was approximately 22, with much faster response and recovery times. In addition, the N-rGO/ZnO-0.3 sensor revealed great stability, a low detection limit of 100 ppb, and an excellent selectivity toward NO versus other gases (NO2, H2, CO, NH3, and CH4), especially at the ppb level. More interestingly, when exposed to oxidizing and reducing gases, unlike conventional semiconductor sensitive materials with resistances that normally change in the opposite direction, only the increase in the resistance is surprisingly and incomprehensibly observed for the N-rGO/ZnO-0.3 sensor. The peculiar sensing behaviors cannot be explained by the conventional theory of the adsorption process, redox reactions on the surfaces, and the well-defined p–n junction between N-rGO and ZnO, originating from the chemical bonding of Zn–C. We propose here for the first time that switchable contribution from dual-conduction paths including the corresponding ZnO channel with the p–n junction and the corresponding N-rGO channel to the sensitivity may exist in the interaction between gases and N-rGO/ZnO-0.3 material. When an oxidizing gas (such as NO) is exposed to the N-rGO/ZnO-0.3 sensor, the contribution from the conductive channel of ZnO nanoparticles and the p–n junction to the sensitivity is dominant. On the contrary, as for a reducing gas (such as H2), the contribution alters to the N-rGO channel as the dominating mode for sensitivity. For gas-sensing behavior of the NGZ-0.1 and NGZ-0.5 sensors, there is only one conduction path from the N-rGO channel for the sensitivity. The model of switchable dual-conduction paths has addressed the mysterious response observed for different gases, which may be utilized to enlighten the understanding of other application problems in nanoscale hybrid materials with a heterogeneous structure.

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Section: Gas-sensing Properties and Potential Mechanismsmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Gas-sensing Properties and Potential Mechanismsmentioning

confidence: 99%

See 2 more Smart Citations

Observation of Switchable Dual-Conductive Channels and Related Nitric Oxide Gas-Sensing Properties in the N-rGO/ZnO Heterogeneous Structure

Qiu

Min

et al. 2020

ACS Appl. Mater. Interfaces

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show abstract

“…A slight increase in peak potential is observed with increasing concentration due to changes in the dielectric constant, with analyte being used as an electrolyte. The increase in the peak current can be attributed to the increased ionic strength at the electrode-electrolyte interface, and hence the extent of the electro-catalytic reaction occurring at the surface of the modified electrode [ 58 , 59 , 60 , 61 ] (schematically shown later in Figure 9).…”

Section: Resultsmentioning

confidence: 99%

A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts

et al. 2017

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Herein, we report a facile synthesis, characterization, and electrochemical sensing application of ZnO nanopeanuts synthesized by a simple aqueous solution process and characterized by various techniques in order to confirm the compositional, morphological, structural, crystalline phase, and optical properties of the synthesized material. The detailed characterizations revealed that the synthesized material possesses a peanut-shaped morphology, dense growth, and a wurtzite hexagonal phase along with good crystal and optical properties. Further, to ascertain the useful properties of the synthesized ZnO nanopeanut as an excellent electron mediator, electrochemical sensors were fabricated based on the form of a screen printed electrode (SPE). Electrochemical and current-voltage characteristics were studied for the determination of picric acid sensing characteristics. The electrochemical sensor fabricated based on the SPE technique exhibited a reproducible and reliable sensitivity of ~1.2 μA/mM (9.23 μA·mM−1·cm−2), a lower limit of detection at 7.8 µM, a regression coefficient (R2) of 0.94, and good linearity over the 0.0078 mM to 10.0 mM concentration range. In addition, the sensor response was also tested using simple I-V techniques, wherein a sensitivity of 493.64 μA·mM−1·cm−2, an experimental Limit of detection (LOD) of 0.125 mM, and a linear dynamic range (LDR) of 1.0 mM–5.0 mM were observed for the fabricated picric acid sensor.

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Selective-detection NO at room temperature on porous ZnO nanostructure by solid-state synthesis method

Huang

Cheng²,

et al. 2019

Journal of Colloid and Interface Science

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Flower-Like ZnO Nanostructure for NO Sensing at Room Temperature

Cited by 5 publications

References 0 publications

Observation of Switchable Dual-Conductive Channels and Related Nitric Oxide Gas-Sensing Properties in the N-rGO/ZnO Heterogeneous Structure

Observation of Switchable Dual-Conductive Channels and Related Nitric Oxide Gas-Sensing Properties in the N-rGO/ZnO Heterogeneous Structure

A Highly-Sensitive Picric Acid Chemical Sensor Based on ZnO Nanopeanuts

Selective-detection NO at room temperature on porous ZnO nanostructure by solid-state synthesis method

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