Ultrasensitive resistivity-based ethanol sensor based on the use of CeO 2 -Fe 2 O 3 core-shell microclusters
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ORIGINAL PAPER
Ultrasensitive resistivity-based ethanol sensor based on the use of CeO2-Fe2O3 core-shell microclusters Nagabandi Jayababu 1
&
Madhukar Poloju 1 & Julakanti Shruthi 1 & Musugu Venkata Ramana Reddy 1
Received: 19 April 2019 / Accepted: 9 September 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019
Abstract This paper presents a method for synthesis of CeO2-Fe2O3 core-shell nanoparticles (CSNPs). These are shown to display enhanced ethanol sensing properties. Synthesis was done via a two-step process, starting with co-precipitation and followed by applying a sol-gel method. High resolution electron microscopy results revealed the core-shell nature of the particles. Surface morphological studies of the CSNPs showed a microcluster-like structure which is assumed to be responsible for the enhanced sensing response. X-ray photoelectron spectroscopy revealed valence states of Fe(III) and Ce(IV). The material was used in a resisitive sensor for ethanol vapor at room temperature (RT), at a typically applied voltage of 5 V. The response of the sensor is higher than that of pristine CeO2 or Fe2O3 sensors towards 100 ppm of ethanol at RT. The lower detection limit is 1 ppm (with a signal change of 23). The response and recovery times are as short as 3 and 7 s, respectively. The sensing mechanism is discussed in detail with respect to n-n heterojunctions formed between n-CeO2 and n-Fe2O3, high catalytic activity of the Fe2O3, and microcluster-like structures of the particles. Keywords Gas sensor . n-n heterojunction . Room temperature . Response/recovery time . Long-term stability . Selectivity . Metal oxide . Morphology . Adsorption
Introduction Metal oxide heterostructure based gas sensors are extensively employed for the detection of numerous gases till date. Low fabrication costs and ease of fabrication, high response, fast response/recovery times, and simple electronic measurements made metal oxide heterostructured materials more advantageous for gas sensing application than other materials [1–4]. Till date, metal oxides are developed in different structures and morphologies, among which core-shell materials are gaining tremendous interest owing to their outstanding
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-019-3809-7) contains supplementary material, which is available to authorized users. * Nagabandi Jayababu [email protected]; [email protected] 1
Thin Films and Nano Materials Research Laboratory, Department of Physics, Osmania University, Hyderabad, Telangana State 500007, India
performances in detecting several toxic gases, explosives, and poisonous gases [5–7]. Different types of core-shell based gas sensors with different combinations of metal oxides have been reported from the past decades [8–10]. Xiaohua Jia et al. prepared α-Fe2O3/TiO2 nanorod@core-shell microspheres using one-step hydrothermal method and studied their acetone sensing properties. Core-shell based sensor was shown superior response (34)
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