0D to 3D ZnO nanostructures and their luminescence, magnetic and sensing properties: Influence of pH and annealing

Shingange, Katekani; Tshabalala, Zamaswazi P.; Dhonge, Baban P.; Ntwaeaborwa, O.M.; Motaung, David E.; Mhlongo, G.H.

doi:10.1016/j.materresbull.2016.09.003

Cited by 47 publications

(10 citation statements)

References 38 publications

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“…Finaly, based on the surface reaction related gas sensing phenomenon, the response values of the ZnO NPs based sensors can also be influenced by the specific surface areas. Generally, higher surface area offer additional active sites for adsorption of gas molecules and this often lead to improved sensor response values 7 . The BET analysis conducted via nitrogen adsorption revealed larger specific surface area values for all Pd-loaded ZnO NPs as compared to that of the pure ZnO NPs.…”

Section: Resultsmentioning

confidence: 99%

“…Besides, larger surface area associated with smaller grain size has been demonstrated to result in the enhancement of the density of intrinsic defects which plays a major role in the sensing performance improvement of ZnO 7,19 . This arises from the fact that the presence of abundant defects more especially donor defects offer more channels for target gas molecules transportation resulting in sensor response increment.…”

Section: Resultsmentioning

confidence: 99%

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A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

Mhlongo

Motaung

Cummings

et al. 2019

Sci Rep

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The gas-detecting ability of nanostructured ZnO has led to significant attention being paid to the development of a unique and effective approach to its synthesis. However, its poor sensitivity, cross-sensitivity to humidity, long response/recovery times and poor selectivity hinder its practical use in environmental and health monitoring. In this context, the addition of noble metals, as dopants or catalysts to modify the ZnO surface has been examined to enhance its sensing performance. Herein, we report preparation of Pd-loaded ZnO nanoparticles via a chemical precipitation approach. Various Pd loadings were employed to produce surface-modified ZnO nanostructure sensors, and their resulting NH 3 sensing capabilities both in dry and humid environments were investigated. Through a comparative gas sensing study between the pure and Pd-loaded ZnO sensors upon exposure to NH 3 at an optimal operating temperature of 350 °C, the Pd-loaded ZnO sensors were found to exhibit enhanced sensor responses and fast response/recovery times. The influence of Pd loading and its successful incorporation into ZnO nanostructure was examined by X-ray diffraction, high resolution-transmission electron microscopy, and X-ray photoelectron spectroscopy. XPS studies demonstrated that in all samples, Pd existed in two chemical states, namely Pd° and Pd 2+ . The possible sensing mechanism related to NH 3 gas is also discussed in detail.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

Mhlongo

Motaung

Cummings

et al. 2019

Sci Rep

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“…Undoubtedly, to date, ZnO is a promising candidate for detecting CO gas; it offers good sensitivity and selectivity, as well as a high surface area for excellent gas sensor response and adsorption sites. For instance, the porous morphology of ZnO increases its surface area, which, along with high electron mobility, excellent electrical properties, and adsorption sites, allow an excellent gas sensor response [ 3 , 7 , 12 , 18 , 28 , 29 , 30 , 43 , 44 ]. However, further research is needed to improve the selectivity and sensitivity for CO gas detection.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in ZnO-Based Carbon Monoxide Sensors: Role of Doping

Pineda-Reyes

Herrera-Rivera

Rojas-Chávez

et al. 2021

Sensors

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Monitoring and detecting carbon monoxide (CO) are critical because this gas is toxic and harmful to the ecosystem. In this respect, designing high-performance gas sensors for CO detection is necessary. Zinc oxide-based materials are promising for use as CO sensors, owing to their good sensing response, electrical performance, cost-effectiveness, long-term stability, low power consumption, ease of manufacturing, chemical stability, and non-toxicity. Nevertheless, further progress in gas sensing requires improving the selectivity and sensitivity, and lowering the operating temperature. Recently, different strategies have been implemented to improve the sensitivity and selectivity of ZnO to CO, highlighting the doping of ZnO. Many studies concluded that doped ZnO demonstrates better sensing properties than those of undoped ZnO in detecting CO. Therefore, in this review, we analyze and discuss, in detail, the recent advances in doped ZnO for CO sensing applications. First, experimental studies on ZnO doped with transition metals, boron group elements, and alkaline earth metals as CO sensors are comprehensively reviewed. We then focused on analyzing theoretical and combined experimental–theoretical studies. Finally, we present the conclusions and some perspectives for future investigations in the context of advancements in CO sensing using doped ZnO, which include room-temperature gas sensing.

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“…Semiconductor metal oxides (SMO) have been regarded as a promising group of sensing materials because of their ease in fabrication, low cost, and sensitivity to a variety of reducing and oxidizing gases. − This group of sensing materials can be synthesized in a variety of dimensions ranging from 0 to 3 dimensions (0D–3D), with all different dimensions revealing different sensing properties. − Of all different dimensions of SMO, one-dimensional (1D) nanostructures, such as nanorods, nanotubes, nanofibers, and nanobelts (NBs), , have been proven to give better gas-sensing performance since they possess large surface area and a strong adsorption/desorption ratio of the analyte gas molecules. − As one of the structures categorized under 1D family, nanobelts (NBs) are of particular interest as they display high surface area with interparticle contact, which are key parameters to facilitate the adsorption/desorption of gas molecules, thus contributing toward sensor performance enhancement …”

Section: Introductionmentioning

confidence: 99%

Ultrafast Detection of Low Acetone Concentration Displayed by Au-Loaded LaFeO₃ Nanobelts owing to Synergetic Effects of Porous 1D Morphology and Catalytic Activity of Au Nanoparticles

2019

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Herein, we report on one-dimensional porous Au-modified LaFeO3 nanobelts (NBs) with high surface area, which were synthesized through the electrospinning method. The incorporation and coverage of Au nanoparticles (NPs) on the surface of the LaFeO3 NBs was achieved by adjusting the HAuCl amount in the precursor solution. Successful incorporation of Au NPs was examined by X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The gas-sensing performance of both the pure and Au/LaFeO3 NB-based sensors was tested toward 2.5–40 ppm of acetone at working temperatures in the range from room temperature to 180 °C. The gas-sensing findings revealed that Au/LaFeO3 NB-based sensor with the Au concentration of 0.3 wt % displayed improved response of 125–40 ppm of acetone and rapid response and recovery times of 26 and 20 s, respectively, at an optimal working temperature of 100 °C. Furthermore, all sensors demonstrated an excellent response toward acetone and remarkable selectivity against NO2, NH3, CH4, and CO. Hence, the Au/LaFeO3-NB-based sensor is a promising candidate for sensitive, ultrafast, and selective acetone detections at low concentrations. The gas-sensing mechanism of the Au/LaFeO3 sensors is explained in consideration of the catalytic activity of the Au NPs, which served as direct adsorption sites for oxygen and acetone.

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0D to 3D ZnO nanostructures and their luminescence, magnetic and sensing properties: Influence of pH and annealing

Cited by 47 publications

References 38 publications

A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

Recent Advances in ZnO-Based Carbon Monoxide Sensors: Role of Doping

Ultrafast Detection of Low Acetone Concentration Displayed by Au-Loaded LaFeO₃ Nanobelts owing to Synergetic Effects of Porous 1D Morphology and Catalytic Activity of Au Nanoparticles

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0D to 3D ZnO nanostructures and their luminescence, magnetic and sensing properties: Influence of pH and annealing

Cited by 47 publications

References 38 publications

A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

A highly responsive NH3 sensor based on Pd-loaded ZnO nanoparticles prepared via a chemical precipitation approach

Recent Advances in ZnO-Based Carbon Monoxide Sensors: Role of Doping

Ultrafast Detection of Low Acetone Concentration Displayed by Au-Loaded LaFeO3 Nanobelts owing to Synergetic Effects of Porous 1D Morphology and Catalytic Activity of Au Nanoparticles

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Ultrafast Detection of Low Acetone Concentration Displayed by Au-Loaded LaFeO₃ Nanobelts owing to Synergetic Effects of Porous 1D Morphology and Catalytic Activity of Au Nanoparticles