Open Access Research Article Issue
Well-designed g-C3N4 nanosheet incorporated Ag loaded Er0.05La0.95FeO3 heterojunctions for isoamyl alcohol detection
Journal of Advanced Ceramics 2024, 13 (6): 736-745
Published: 25 June 2024
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Because the volatile content of isoamyl alcohol increases sharply on the seventh day of wheat mildew infection, isoamyl alcohol can be used as an early biomarker of wheat mildew infection. Currently, only a few sensors for isoamyl alcohol detection have been reported, and these sensors still suffer from low sensitivity and poor moisture resistance. Herein, the isoamyl alcohol sensitivity of 5 at% Er@LaFeO3 (ELFO) was enhanced by loading Ag nanoparticles on the surface of the ELFO microspheres, while the optimal operating temperature was reduced. The moisture resistance of Ag/ELFO was improved by the incorporation of g-C3N4 nanosheets (NSs) on the surface of Ag/ELFO through electrostatic self-assembly. Given the requirements for practical applications in grain granaries, the sensing behavior of a Ag/ELFO-based sensor incorporating g-C3N4 NSs at 20% relative humidity (RH) was systematically studied, and the sensor demonstrated excellent repeatability, long-term stability, and superior selectivity (791 at 50 ppm) for isoamyl alcohol with a low limit of detection (LOD = 75 ppb). Furthermore, the practical results obtained for wheat at different mildew stages further confirmed the potential of the g-C3N4/Ag/ELFO-based sensor for monitoring the early mildew stage of wheat. This work may offer guidance for enhancing the moisture resistance of gas-sensitive materials through the strategy of employing composite nanomaterials.

Open Access Research Article Issue
Urchin-like Na-doped zinc oxide nanoneedles for low-concentration and exclusive VOC detections
Journal of Advanced Ceramics 2024, 13 (4): 507-517
Published: 30 April 2024
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In the early-stage diagnosis of lung cancer, the low-concentration (< 5 ppm) volatile organic compounds (VOCs) are extensively identified to be the biomarkers for breath analysis. Herein, the urchin-like sodium (Na)-doped zinc oxide (ZnO) nanoneedles were synthesized through a hydrothermal strategy with the addition of different contents of citric acid. The Na-doped ZnO gas sensor with a 3 : 1 molar ratio of Na+ and citric acid showed outstanding sensing properties with an optimal selectivity to various VOCs (formaldehyde (HCOH), isopropanol, acetone, and ammonia) based on working temperature regulation. Specifically, significantly enhanced sensitivity (21.3@5 ppm) compared with pristine ZnO (~7-fold), low limit of detection (LOD) (298 ppb), robust humidity resistance, and long-term stability of formaldehyde sensing performances were obtained, which can be attributed to the formation of a higher concentration of oxygen vacancies (20.98%) and the active electron transitions. Furthermore, the improved sensing mechanism was demonstrated by the exquisite band structure and introduction of the additional acceptor level, which resulted in the narrowed bandgap of ZnO.

Open Access Research Article Issue
Ultrasensitive room-temperature geranyl acetone detection based on Fe@WO3−x nanoparticles in cooked rice flavor analysis
Journal of Advanced Ceramics 2023, 12 (8): 1547-1561
Published: 18 July 2023
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In the assessment of food quality, geranyl acetone plays a crucial role as a volatile organic compound (VOC) biomarker for diverse agricultural products, while the ultralow concentration detection meeting application requirements has been barely studied. Herein, an iron (Fe)-doped WO3−x gas sensor was employed for greatly sensitive, selective, and scalable geranyl acetone detection. The results proved that precisely-regulated oxygen vacancy (OV) and sophisticatedly-active electron transition of Fe-doped WO3−x nanoparticles were fulfilled by modifying the doping amount of Fe3+, leading to the prominently enhanced sensitivity (23.47 at 6 ppm), low limit of detection (LOD) (237 ppb), optimal selectivity, and outstanding long-term stability. Furthermore, the enhancing mechanism of gas sensing performance was substantiated through density functional theory (DFT) calculation, while the practical application for the evaluation of spoiled cooked rice was conducted as well. This study demonstrates a reliable method for detecting a VOC biomarker in cooked rice, which can ensure food security and improve palatability of cooked rice.

Open Access Research Article Issue
Synergistic coupling of 0D–2D heterostructure from ZnO and Ti3C2Tx MXene-derived TiO2 for boosted NO2 detection at room temperature
Nano Materials Science 2023, 5 (4): 421-428
Published: 24 February 2023
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2D MXenes are highly attractive for fabricating high-precision gas sensors operated at room temperature (RT) due to their high surface-to-volume ratio. However, the limited selectivity and low sensitivity are still long-standing challenges for their further applications. Herein, the self-assembly of 0D–2D heterostructure for highly sensitive NO2 detection was achieved by integrating ZnO nanoparticles on Ti3C2Tx MXene-derived TiO2 nanosheets (designated as ZnO@M−TiO2). ZnO nanoparticles can not only act as spacers to prevent the restacking of M−TiO2 nanosheets and ensure effective transfer for gas molecules, but also enhance the sensitivity of the sensor the through trapping effect on electrons. Meanwhile, M−TiO2 nanosheets facilitate gas diffusion for rapid sensor response. Benefiting from the synergistic effect of individual components, the ZnO@M−TiO2 0D–2D heterostructure-based sensors revealed remarkable sensitivity and excellent selectivity to low concentration NO2 at RT. This work may facilitate the sensing application of MXene derivative and provide a new avenue for the development of high-performance gas sensors in safety assurance and environmental monitoring.

Open Access Review Issue
Metal oxide semiconductor gas sensing materials for early lung cancer diagnosis
Journal of Advanced Ceramics 2023, 12 (2): 207-227
Published: 10 January 2023
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The urgency of early lung cancer (LC) diagnosis and treatment has been more and more significant. Exhaled breath analysis using gas sensors is a promising way to find out if someone has LC due to its low-cost, non-invasive, and real-time monitoring compared with traditional invasive diagnostic techniques. Among sensor-based gas detection techniques, metal oxide semiconductor’s gas sensors are one of the most important types. This review presents the-state-of-art in metal oxide gas sensors for the diagnosis of early LC. First, the exhaled breath biomarkers are described with emphasis on the concentration of abnormal volatile organic compounds (VOCs) caused by the metabolic process of LC cells. Then, the research status of metal oxide gas sensors in LC diagnosis is summarized. The sensing performance and enhancement strategy of biomarkers provided by metal oxide semiconductor materials are reviewed. Another effective way to improve VOC detection performance is to build a gas sensor array. At the same time, various gas sensors combined with self-powered techniques are mentioned to display a broad development prospect in breath diagnosis. Finally, metal oxide gas sensor-based LC diagnosis is prospected.

Open Access Research Article Issue
Oxygen vacancy engineering on cerium oxide nanowires for room-temperature linalool detection in rice aging
Journal of Advanced Ceramics 2022, 11 (10): 1559-1570
Published: 11 October 2022
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It is a huge challenge for metal oxide semiconductor gas sensors to inspect volatile organic compounds (VOCs) at room temperature (RT). Herein, the effective utilization of cerium oxide (CeO2) nanowires for RT detection of VOCs was realized via regulating its surface chemical state. Oxygen vacancy engineering on CeO2 nanowires, synthesized via hydrothermal method, can be manipulated by annealing under various controlled atmospheres. The sample annealed under 5%H2+95%Ar condition exhibited outstanding RT sensing properties, displaying a high response of 16.7 towards 20 ppm linalool, a fast response and recovery time (16 and 121 s, respectively), and a low detection of limit of 0.54 ppm. The enhanced sensing performance could be ascribed for the synergistic effects of its nanowire morphology, the large specific surface area (83.95 m2/g), and the formation of extensive oxygen vacancy accompanied by an increase in Ce3+. Additionally, the practicability of the sensor was verified via two varieties of rice (Indica and Japonica rice) stored in various periods (1, 3, 5, 7, 15, and 30 d). The experimental results revealed that the sensor was able to distinguish Indica rice from Japonica rice. Accordingly, the as-developed sensor delivers a strategic material to develop high-performance RT electronic nose equipment for monitoring rice quality.

Open Access Research Article Issue
Low concentration isopropanol gas sensing properties of Ag nanoparticles decorated In2O3 hollow spheres
Journal of Advanced Ceramics 2022, 11 (3): 379-391
Published: 11 February 2022
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In order to detect low concentrations of volatile organic compounds (VOCs) for the early diagnosis of lung cancer, sensors based on hollow spheres of In2O3 were prepared through the soft template method. Ag nanoparticle decorated In2O3 composites were synthesized via dipping and annealing. The microstructure, phase composition, element distribution, and state of Ag were analyzed by the scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The gas sensing tests showed that Ag-In2O3 sensors had the highest response to isopropanol at 300 ℃. The best response of Ag-In2O3 composite sensor was 5.2, which had a significant improvement compared with only In2O3. Moreover, the response and recovery time of Ag-In2O3 composite sensor was significantly shortened. The improved sensing properties of Ag-In2O3 composite sensor could be attributed to the Schottky barrier created at Ag-In2O3 interface and catalytical effect of Ag.

Open Access Review Issue
Micro-nano structured functional coatings deposited by liquid plasma spraying
Journal of Advanced Ceramics 2020, 9 (5): 517-534
Published: 10 August 2020
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Inspired by the micro-nano structure on the surface of biological materials or living organisms, micro-nano structure has been widely investigated in the field of functional coatings. Due to its large specific surface area, porosity, and dual-scale structure, it has recently attracted special attention. The typical fabrication processes of micro-nano structured coatings include sol-gel, hydrothermal synthesis, chemical vapor deposition, etc. This paper presents the main features of a recent deposition and synthesis technique, liquid plasma spraying (LPS). LPS is an important technical improvement of atmospheric plasma spraying. Compared with atmospheric plasma spraying, LPS is more suitable for preparing functional coatings with micro-nano structure. Micro-nano structured coatings are mainly classified into hierarchical-structure and binary-structure. The present study reviews the preparation technology, structural characteristics, functional properties, and potential applications of LPS coatings with a micro-nano structure. The micro-nano structured coatings obtained through tailoring the structure will present excellent performances.

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