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

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

Impurity doping is a promising method to impart new properties to various materials. Due to their unique optical, magnetic, and electrical properties, rare-earth ions have been extensively explored as active dopants in inorganic crystal lattices since the 18th century. Rare-earth doping can alter the crystallographic phase, morphology, and size, leading to tunable optical responses of doped nanomaterials. Moreover, rare-earth doping can control the ultimate electronic and catalytic performance of doped nanomaterials in a tunable and scalable manner, enabling significant improvements in energy harvesting and conversion. A better understanding of the critical role of rare-earth doping is a prerequisite for the development of an extensive repertoire of functional nanomaterials for practical applications. In this review, we highlight recent advances in rare-earth doping in inorganic nanomaterials and the associated applications in many fields. This review covers the key criteria for rare-earth doping, including basic electronic structures, lattice environments, and doping strategies, as well as fundamental design principles that enhance the electrical, optical, catalytic, and magnetic properties of the material. We also discuss future research directions and challenges in controlling rare-earth doping for new applications.

Rare-Earth Doping in Nanostructured Inorganic Materials.

This paper reports the synthesis and characterization of NiO-ZnO nanodisks synthesized through a facile hydrothermal method. The morphological characterizations confirmed the formation of well-defined nanodisks in high density with an average thickness of 60 ± 5 nm. The x-ray diffraction analysis confirmed the well incorporation of the NiO into the matrix of ZnO crystal and the average crystallite size for the NiO-ZnO nanodisks was found to be 39.71 nm. The compositional analysis revealed the formation of pure NiO-ZnO nanostructures. The synthesized NiO-ZnO nanodisks were used as electrode materials to fabricate Sulfur dioxide (SO2) gas sensors and the gas sensor response and recovery times were systematically analyzed with respect to the operating temperatures and the SO2 gas concentration. The observed sensor gas response, response time and recovery time of the fabricated NiO-ZnO nanodisks based gas sensor were 16.25, 52 s and 41 s, respectively, towards 20 ppm SO2 gas at an optimized temperature of 240 °C. Thus, it is believed that the NiO-ZnO nanodisks could be a promising candidate for the fabrication of efficient gas sensors towards toxic and hazardous gases.

High sensitive and low-concentration sulfur dioxide (SO2) gas sensor application of heterostructure NiO-ZnO nanodisks

Comparative study on gas sensing properties of rare earth (Tb, Dy and Er) doped ZnO sensor

A review on recent progress of p-type nickel oxide based gas sensors: Future perspectives

In the present work, influence of terbium doping on structural, morphological, optical and gas sensing properties of zinc oxide has been studied. A chemical route was adopted for synthesis of pure and terbium (Tb) doped zinc oxide. X-ray diffraction study confirmed the formation of hexagonal wurtzite structure for synthesized materials. Raman analysis revealed the shifting and broadening of peaks with increase in Tb concentration. The presence of terbium in ZnO and its oxidation states was confirmed using X-ray photoelectron spectroscopy. Photoluminescence emissions indicated increase in concentration of oxygen vacancies with introduction of dopant. Gas sensors were fabricated out of synthesized samples and it was observed that doped samples have significantly high sensing response, temperature dependent selectivity toward ethanol and acetone, and sensors were able to detect even low concentration (∼10 ppm) of these vapors. The temperature dependent selectivity of terbium doped ZnO depends on target gas which may be ascribed to interaction of target gas molecules and doped metal oxide surface at optimum operating temperature. It was found that 4% Tb doped ZnO sensor exhibited maximum sensor response toward ethanol and acetone. The enhanced sensing response has been attributed to increase in oxygen vacancies, reduction in particle size, large structural disorders and high surface basicity.

Temperature dependent selective and sensitive terbium doped ZnO nanostructures

Influence of terbium (Tb) doping on structural, optical and morphological properties of radio frequency magnetron-sputtered ZnO films has been investigated using various characterization techniques. Investigations revealed the formation of hexagonal wurtzite structure of ZnO with preferential c-axis orientation, presence of oxygen vacancies, modification of surface morphology and surface roughness, and confirmation of oxidation states of elements present in ZnO and Tb-doped ZnO films. Subsequently, films deposited with varied Tb concentrations have been tested for ethanol vapor sensing. Doped films exhibited reduction in optimum operable temperature, enhancement in ethanol sensing response and improvement in response/recovery time in comparison with pristine ZnO. The observed improvement in doped samples has been attributed to modifications in surface properties such as morphology, surface roughness, basicity, structural disorder and oxygen vacancies introduced due to dopant incorporation.

Deposition, characterization and gas sensors application of RF magnetron-sputtered terbium-doped ZnO films

Structural, optical and dielectric properties of lead doped ZnS nanoparticles

The present work reports the effect of introducing carbon nanotubes into indium oxide on structural, morphological, optical and acetone sensing properties. To have insight into the structural, morphological and optical properties of the synthesized samples, various characterization techniques such as X-ray diffraction, transmission electron microscopy, BET, Fourier transform infra-red, UV–vis and Raman spectroscopy were employed. The sensors were fabricated out of the synthesized samples to test their response towards acetone. The synthesized In2O3/CNT sensor exhibits enhanced sensing performance and is capable of detecting concentration of acetone as low as 10 ppm with sensor response magnitude ∼4 at 300 °C.

Anita Hastir

Papers

Comparative study on gas sensing properties of rare earth (Tb, Dy and Er) doped ZnO sensor

Temperature dependent selective and sensitive terbium doped ZnO nanostructures

Deposition, characterization and gas sensors application of RF magnetron-sputtered terbium-doped ZnO films

Structural, optical and dielectric properties of lead doped ZnS nanoparticles

Hydrothermally synthesized heterostructures of In2O3/MWCNT as acetone gas sensor