Green light activated hydrogen sensing of nanocrystalline composite ZnO-In2O3 films at room temperature

Abstract

The possibility of reducing the operating temperature of H2 gas sensor based on ZnO-In2O3 down to room temperature under green illumination is shown. It is found that sensitivity of ZnO-In2O3 composite to H2 nonmonotonically depends on the oxides’ content. The optimal ratio between the components is chosen. The new mechanism of nanocrystalline ZnO-In2O3 sensor sensitivity to H2 under illumination by green light is proposed. The mechanism considers the illumination turns the composite into nonequilibrium state and the photoconductivity change in the H2 atmosphere is linked with alteration of nonequilibrium charge carriers recombination rate.

Nanocrystalline Complex Oxides ZnxCo3–xO4: Cobalt and Zinc Ions Impact on Large Growth of Conductivity

“…It should be noted that a mechanism that explains the increase in the conductivity of cobalt oxide with the introduction of zinc into its structure has not yet been identified. It is known that defects in the crystal structure of metal oxides have a significant effect on both the magnitude and the mechanisms of conductivity. , In addition, defects can act as recombination centers of nonequilibrium charge carriers, affecting photoelectric properties that may be important for sensors operating under additional illumination . Therefore, the aim of this work was to synthesize Zn x Co 3– x O 4 samples with increased conductivity compared to Co 3 O 4 , as well as to carry out a comparative study of morphology, electrophysical properties, nature, and properties of defects in the obtained materials.…”

Effect of Zinc Oxide Modification by Indium Oxide on Microstructure, Adsorbed Surface Species, and Sensitivity to CO

“…Besides bulk doped materials, heterostructures of ZnO with M(III) oxides are often obtained. The nanocomposites ZnO/In 2 O 3 have been synthesized with different morphologies and in a wide composition range for the use as gas sensors (Rambu et al, 2011;Singh et al, 2011;Lee et al, 2013Lee et al, , 2017Trakhtenberga et al, 2013;Ma et al, 2016;Espid and Taghipour, 2017;Ilin et al, 2017;Wang et al, 2017;Wei et al, 2017;Zou et al, 2017;Choo et al, 2018;Guo et al, 2018;Liu et al, 2018), humidity sensors (Liang et al, 2012), photocatalysts (Wei et al, 2017;Markova et al, 2018), UV-light detectors (Wang et al, 2009). The studies of gas sensor behavior suggested the increased gas sensitivity of composites, in comparison to pure oxides.…”

“…The studies of gas sensor behavior suggested the increased gas sensitivity of composites, in comparison to pure oxides. The increased sensitivity was revealed either to reducing analyte gases like hydrogen (Trakhtenberga et al, 2013;Ilin et al, 2017;Choo et al, 2018), ammonia (Rambu et al, 2011) and (CH 3 ) 3 N (Lee et al, 2013), volatile organic compounds (Singh et al, 2011;Ma et al, 2016;Lee et al, 2017;Wang et al, 2017;Wei et al, 2017;Guo et al, 2018;Liu et al, 2018), or when the oxidizing gases were detected (Espid and Taghipour, 2017;Zou et al, 2017). The data on optimal Zn:In ratios in the gas sensors are contradictory and likely dependent on the synthesis procedure, materials morphology and microstructure and the properties of gas molecules to be detected.…”

“…The data on optimal Zn:In ratios in the gas sensors are contradictory and likely dependent on the synthesis procedure, materials morphology and microstructure and the properties of gas molecules to be detected. For example, improved sensitivity to butanol and chlorine was found for nanorods and nanoparticles of ZnO modified by In 2 O 3 (3-4 at % indium) (Zou et al, 2017;Liu et al, 2018), while ZnO/In 2 O 3 heterostructures with comparable molar fractions were established for sensing H 2 (Trakhtenberga et al, 2013;Ilin et al, 2017), trimethylamine (Lee et al, 2013) and NO 2 (Espid and Taghipour, 2017). The mechanism of sensitization due to the ZnO/In 2 O 3 heterojunctions is most often speculated based on the electron band energy model at the interface between two oxides proposed in Markova et al (2018).…”

Электрические Свойства Тонких Пленок Оксида Индия, Полученных Методом Плазменно-Термического Испарения

“…Тонкие пленки оксида индия находят применение в качестве прозрачных проводящих слоев дисплеев [1] и солнечных элементов [2], на их основе изготавливают транзисторы [3,4] и газовые сенсоры [5][6][7][8]. Электрические свойства пленок оксида индия сильно зависят от метода синтеза и структуры.…”