Semi shield driven p-n heterostructures and their role in enhancing the room temperature ethanol gas sensing performance of NiO/SnO2 nanocomposites

• Published in: Ceramics international 2019-08, Vol.45 (12), p.15134-15142
• Main Authors: Jayababu, Nagabandi, Poloju, Madhukar, Shruthi, Julakanti, Reddy, M.V. Ramana
• Format: Article
• Language: English
• Subjects: Gas sensor; NiO/SnO2; p-n heterostructure; Room temperature; Semi-shielding
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2019.04.255

The demand for the development of gas sensors operable at room temperature is increasing due to the uncountable drawbacks of high temperature gas sensors. This contribution describes the fabrication of room temperature ethanol sensor. The synthesis of NiO semi shielded SnO2 (NiO/SnO2) nanocomposites (NCs) was done via a simple two-step process, started with co-precipitation technique and then followed by sol-gel method. High resolution electron microscope (HRTEM) results indicated the semi shielding of NiO on SnO2 nanoparticles (NPs). Surface morphological studies of the fabricated sensors show the porous nature of the samples which further helps in enhanced sensing response. X-ray photoelectron spectroscope (XPS) results of NiO/SnO2 NCs revealed the valence states of Ni (+2) and Sn (+4). Excellent gas sensing response of the NiO/SnO2 sensor towards ethanol at room temperature was observed from the gas sensing studies. The response of NiO/SnO2 (∼140) was nearly 9 times higher than SnO2 sensor (∼15) and nearly 11 times higher than NiO sensor (12.98) towards 100 ppm ethanol at room temperature. The observed response and recovery times of NiO/SnO2 were 23 s and 13 s respectively. The p-n heterostructure formed between p-NiO and n-SnO2, and high chemical sensitization and catalytic activity of the NiO are the main contributors for the excellent sensing performance of NiO/SnO2 sensor.