Architectural tailoring of orthorhombic MoO 3 nanostructures toward efficient NO 2 gas sensing
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Architectural tailoring of orthorhombic MoO3 nanostructures toward efficient NO2 gas sensing B. Geeta Rani1, R. Saisri1, Saraswathi Kailasa1, M. Sai Bhargava Reddy1, Hussen Maseed2, and K. Venkateswara Rao1,* 1 2
Center for Nanoscience and Technology, Institute of Science and Technology, JNTU Hyderabad, Hyderabad, India School of Engineering Sciences and Technology, University of Hyderabad, Gachibowli, Hyderabad 500046, India
Received: 29 October 2019
ABSTRACT
Accepted: 23 March 2020
In the present study, an architectural tailoring strategy was established to tune crystalline orthorhombic molybdenum trioxide (a-MoO3) to obtain nanostructures such as nanorods, dumbbell-shaped nanorods and hierarchical nanodisks for chemiresistive gas sensors. The different types of a-MoO3 nanostructures were synthesized by adopting controlled hydrothermal reaction conditions such as reaction time and temperature. The morphological variation of nanostructures revealed changes in crystalline parameters, such as size, micro-strain, shape, surface area, and porosity. The microstructural effects and shape of the aMoO3 nanostructures were studied to determine their influence on the analytical characteristics of a gas sensor, the sensitivity, response time, and selectivity toward NO2 analyte gas. The high surface area of a-MoO3 nanorods showed a high sensitivity of 84% at an optimal operating temperature of 110 °C, with response and recovery times at 45 and 42 s, respectively, then dumbbell-shaped nanorods is reduced with 10% lower sensitivity than nanorods at 74% at a temperature of 130 °C. Nanodisks showed the least response compared to all the synthesized structures. All nanostructures of a-MoO3 exhibited good selectivity for the NO2 analytical gas with respect to interfering gases such as CO2, NH3, ethanol, methanol, and acetone and in addition, good stability and reproducibility have been observed.
Published online: 3 April 2020
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Introduction In recent years, considerable research effort has been devoted to the development of gas sensors to detect toxic gases due to their increase in environmental pollution. Among the gaseous species, NO2, O3, Cl2, CH4, SO2, and volatile compounds (VOCs) are
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https://doi.org/10.1007/s10853-020-04601-x
considered a health threat when their air content exceeds a specific limit. In urban areas, more attention is being paid to NO2, an oxidizing gas found in the combustion of automobile exhaust, power plants, and industrial emissions [1–3]. Also, it reacts with the ambient air atmosphere to produce acid rain that harms the environment and can cause many
8110 respiratory health problems in humans [4]. Nanomaterials with a high surface area-to-volume ratio offer many advantages for their use in gas detection. Numerous studies have been conducted on metal oxides, polymers, solid electrolytes, and metals as gas sensing materials for detecting air pollutants [5–7]. The expa
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