Considering metal oxide nanoparticles as important technological materials, authors provide a comprehensive review of researches on metal oxide nanoparticles, their synthetic strategies, and techniques, nanoscale physicochemical properties, defining specific industrial applications in the various fields of applied nanotechnology. This work expansively reviews the recent developments of semiconducting metal oxide gas sensors for environmental gases including CO2, O2, O3, and NH3; highly toxic gases including CO, H2S, and NO2; combustible gases such as CH4, H2, and liquefied petroleum gas; and volatile organic compounds gases. The gas sensing properties of different metal oxides nanoparticles towards specific target gases have been individually discussed. Promising metal oxide nanoparticles for sensitive and selective detection of each gas have been identified. This review also categorizes metal oxides sensors by analyte gas and also summarizes the major techniques and synthesis strategies used in nanotechnology. Additionally, strategies, sensing mechanisms and related applications of semiconducting metal oxide materials are also discussed in detail. Related applications are innumerable trace to ultratrace-level gas sensors, batteries, magnetic storage media, various types of solar cells, metal oxide nanoparticles applications in catalysis, energy conversion, and antennas (including microstrip and patch-type optically transparent antennas), rectifiers, optoelectronic, and electronics.

/pdf/metal-oxide-nanoparticles-and-their-applications-in-44aw1haeng.pdf

Metal oxide nanoparticles and their applications in nanotechnology

https://www.econstor.eu/bitstream/10419/244006/1/1693663112.pdf

Enhanced sensing performance of ZnO nanostructures-based gas sensors: A review

Chemiresistive gas sensors with low power consumption, fast response, and reliable fabrication process for a specific target gas have been now created for many applications. They require both sensitive nanomaterials and an efficient substrate chip for heating and electrical addressing. Herein, a near room working temperature and fast response triethylamine (TEA) gas sensor has been fabricated successfully by designing gold (Au)-loaded ZnO/SnO2 core-shell nanorods. ZnO nanorods grew directly on Al2O3 flat electrodes with a cost-effective hydrothermal process. By employing pulsed laser deposition (PLD) and DC-sputtering methods, the construction of Au nanoparticle-loaded ZnO/SnO2 core/shell nanorod heterostructure is highly controllable and reproducible. In comparison with pristine ZnO, SnO2, and Au-loaded ZnO, SnO2 sensors, Au-ZnO/SnO2 nanorod sensors exhibit a remarkably high and fast response to TEA gas at working temperatures as low as 40 °C. The enhanced sensing property of the Au-ZnO/SnO2 sensor is also discussed with the semiconductor depletion layer model introduced by Au-SnO2 Schottky contact and ZnO/SnO2 N-N heterojunction.

Near Room Temperature, Fast-Response, and Highly Sensitive Triethylamine Sensor Assembled with Au-Loaded ZnO/SnO2 Core–Shell Nanorods on Flat Alumina Substrates

Hydrogen sensors based on noble metal doped metal-oxide semiconductor: A review

In this work, a novel branched heterostructural composite composed of nanorods ZnO backbone and SnO2 branches was prepared via a facile one-step hydrothermal method. The morphology, structure and component of the SnO2/ZnO composite was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and elemental mapping analysis. The evolution process of the SnO2/ZnO composite was observed by SEM that the SnO2 branches gradually grow on ZnO backbones. The composite with novel heterostructure was applied as the sensing material for the fabrication of gas sensor, and their gas sensing properties were tested for response to various gases. Compared to pure ZnO gas sensors the branched SnO2/ZnO gas sensor exhibited enhanced gas sensing properties toward ethanol, giving a response of 18.1–100 ppm.

One step synthesis of branched SnO2/ZnO heterostructures and their enhanced gas-sensing properties

This work reports the synthesis and detailed investigation on ZnO–SnO 2 composite type hydrogen sensor prototype. The sensor material was structurally and morphologically characterized by X-ray diffraction technique and scanning electron microscopy, respectively. The gas sensing behaviour of the fabricated sensor prototype was investigated for varied concentration of test gases at different temperature. The cross-response of this sensor to other gases, viz. methane and carbon mono-oxide was also investigated, which showed good selectivity, excellent response and reproducibility to hydrogen at 150 °C.

ZnO–SnO2 based composite type gas sensor for selective hydrogen sensing

ZnO nanorods in the form of thin films were synthesized by a facile chemical route and the effect of annealing temperature on the structure and sensitivity of such ZnO-based sensors was studied in detail towards methane sensing. Morphological analyses of such films were carried out by scanning electron microscopy, whereas, the crystalline structure and phase purity of the films were analysed by X-ray diffraction technique. The films were observed to display a gradual change in their morphology from granular to dense nanorods and each of them was used to fabricate methane sensor prototype. They were also tested for temperature-dependent methane-sensing capability with varying methane concentrations. The optimized sensor exhibited highest gas response of ~80% at 250 °C with significantly low response and recovery time.

Effect of Annealing Temperature on the Morphology and Sensitivity of the Zinc Oxide Nanorods-Based Methane Senor

Zinc Oxide Nano-Platelets for Effective Methane Gas-Sensing Applications

We report on the fabrication of Zinc Oxide (ZnO) nanorod based H2 sensor using a simple chemical route. ZnO films were deposited on Si substrate followed by annealing and used to detect hydrogen. The surface morphology and crystal structure of the fabricated ZnO system was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The gas sensing of H2 in the concentration range 0.1-1 vol % in dry air was studied using current-voltage measurements. Gas sensing mechanism is discussed.

ZnO nano-rod based hydrogen sensor

We report on the fabrication of pure Zinc Oxide (ZnO) and composite ZnO-SnO2 material based H2 sensor using a simple chemical route. The surface morphology and crystal structure of the samples were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The gas sensing performance of the sensor to Hydrogen in dry air was studied using current-voltage measurements. Selectivity of the sensor against carbon mono-oxide is studied. The obtained result demonstrates a promising approach in the development of low cost selective hydrogen sensor.

C. Roychaudhury

Papers

ZnO–SnO2 based composite type gas sensor for selective hydrogen sensing

Effect of Annealing Temperature on the Morphology and Sensitivity of the Zinc Oxide Nanorods-Based Methane Senor

Zinc Oxide Nano-Platelets for Effective Methane Gas-Sensing Applications

ZnO nano-rod based hydrogen sensor

Enhanced hydrogen sensitivity and selectivity of ZnO-SnO 2 based sensor