Oxidation behaviour of carbon monoxide at the photostimulated surface of ZnO nanowires

Wang, Ch. Y.; Kinzer, M.; Youn, Seul Ki; Ramgir, Niranjan S.; Kunzer, M.; Köhler, K.; Zacharias, Margit; Cimalla, V.

doi:10.1088/0022-3727/44/30/305302

Cited by 7 publications

(3 citation statements)

References 36 publications

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“…A similar result was observed by Wang, who used vertically aligned ZnO nanowires for CO sensing with light illumination at low intensity. Different from other CO sensing results where CO acts as the reducing gas, here CO caused the resistance of ZnO to increase more after removing the LED source, which indicated that CO worked as an oxidizing gas that trapped electrons from ZnO [ 53 ]. In conclusion, it is believed that the reported results confirm that there is no absolute measure on whether an analyte is reductive or oxidative, it is a question of how the energy levels of the analyte are relative to the sensing material.…”

Section: Pure Metal Oxide Materials For Gas Sensingcontrasting

confidence: 64%

Light-Activated Metal Oxide Gas Sensors: A Review

Fang

2017

Micromachines

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Conductometric gas sensors facilitated by photons have been investigated for decades. Light illumination may enhance device attributes including operational temperature, sensing sensitivity and selectivity. This paper aims to provide an overview on the progress of light-activated gas sensors, with a specific focus on sensors based on metal oxides. The material systems that have been studied include pure metal oxides, heterostructures of semiconductor-metal oxides and metal-metal oxides, and metal oxides with dopant. Other reported works on the use of different nanostructures such as one-dimensional and porous nanostructures, study of sensing mechanisms and the interplay between various factors are also summarized. Possible directions for further improvement of sensing properties, through optimizing the size of nanomaterials, film thickness, light intensity and wavelength are discussed. Finally, we point out that the main challenge faced by light-activated gas sensors is their low optical response, and we have analyzed the feasibility of using localized surface plasmon resonance to solve this drawback. This article should offer readers some key and instructive insights into the current and future development of light-activated gas sensors.

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Section: Pure Metal Oxide Materials For Gas Sensingcontrasting

confidence: 64%

Light-Activated Metal Oxide Gas Sensors: A Review

Fang

2017

Micromachines

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“…The response to all other interfering coexisting residual gases in the detecting system (such as H 2 O or O 2 , which is below 1 ppm) is marginal and can be excluded. 27 In the present work, the oxidizing behavior of CO was additionally investigated using XPS studies. For this, a fresh sample with dense NWs was scanned at each step of UV pretreatment and CO exposure and subsequently compared to the as-grown NWs.…”

Section: Pl Measurement Of Zno Nws At Rt As Shown Inmentioning

confidence: 99%

Catalyst-Free Growth of ZnO Nanowires Based on Topographical Confinement and Preferential Chemisorption and Their Use for Room Temperature CO Detection

et al. 2010

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Two novel approaches for patterned growth of ZnO nanowires (NWs) based on the selective deposition of zinc acetate (ZA) solution precursors are presented and compared. The first is using the topographical confinement within a photoresist pattern on Si/SiO 2 substrates (type I), and the second is using preferential chemisorption on self-assembled monolayer modified Au electrodes on Si/SiO 2 substrates (type II). In both approaches, the ZnO seeds from the ZA solution form crystallites without severe defects over a large area via annealing at 350°C. These seed layers were used to grow ZnO NWs via a catalyst-free vapor-phase deposition method using temperatures of up to 900°C. The presented method is effective for realizing NW growth on both Si and Au electrodes by preserving the electrode configuration even at such high temperatures used for NW growth, which is a novelty and crucial for future sensor applications. As a result NWs connected through metal contact pads or electrodes have been realized in very simple and effective way. As a test of principle the resulting configurations were used to demonstrate a highly sensitive room temperature CO sensor. A CO concentration as low as 120 ppb was detected using both types of sensors. The type II sensor exhibited enhanced sensing properties compared to that of type I.

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“…When explaining the mechanism of sensor properties, some authors consider the direct interaction of chemisorbed molecules of organic substances with photoexcited charge carriers, similar to photocatalytic reactions [ 49 , 185 , 186 , 187 ]. For example, in work [ 49 ], oxidation of ethanol vapors on the ZnO surface under UV irradiation is described by the following processes (Equations (21)–(23)):

…”

Section: Mechanisms Of Light Activated Gas Sensingmentioning

confidence: 99%

Light Activation of Nanocrystalline Metal Oxides for Gas Sensing: Principles, Achievements, Challenges

2021

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The review deals with issues related to the principle of operation of resistive semiconductor gas sensors and the use of light activation instead of thermal heating when detecting gases. Information on the photoelectric and optical properties of nanocrystalline oxides SnO2, ZnO, In2O3, and WO3, which are the most widely used sensitive materials for semiconductor gas sensors, is presented. The activation of the gas sensitivity of semiconductor materials by both UV and visible light is considered. When activated by UV light, the typical approaches for creating materials are (i) the use of individual metal oxides, (ii) chemical modification with nanoparticles of noble metals and their oxides, (iii) and the creation of nanocomposite materials based on metal oxides. In the case of visible light activation, the approaches used to enhance the photo- and gas sensitivity of wide-gap metal oxides are (i) doping; (ii) spectral sensitization using dyes, narrow-gap semiconductor particles, and quantum dots; and (iii) addition of plasmon nanoparticles. Next, approaches to the description of the mechanism of the sensor response of semiconductor sensors under the action of light are considered.

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Oxidation behaviour of carbon monoxide at the photostimulated surface of ZnO nanowires

Cited by 7 publications

References 36 publications

Light-Activated Metal Oxide Gas Sensors: A Review

Light-Activated Metal Oxide Gas Sensors: A Review

Catalyst-Free Growth of ZnO Nanowires Based on Topographical Confinement and Preferential Chemisorption and Their Use for Room Temperature CO Detection

Light Activation of Nanocrystalline Metal Oxides for Gas Sensing: Principles, Achievements, Challenges

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