Shape selective comprehensive gas sensing study of different morphological manganese-cobalt oxide based nanocomposite as potential room temperature hydrogen gas sensor

• Published in: Sensors and actuators. B, Chemical Chemical, 2023-04, Vol.380, p.133348, Article 133348
• Main Authors: Maji, Banalata, Barik, Bapun, Sahoo, Shital Jyotsna, Achary, L. Satish K., Kumar Sahoo, Kiran, Kar, Jyoti Prakash, Dash, Priyabrat
• Format: Article
• Language: English
• Subjects: Carrier mobility; Chemical sensors; Cobalt oxides; Crystal defects; Current carriers; Electrical resistivity; Flakes (defects); Flowers; Gas sensor; Gas sensors; Graphene; Heterojunctions; Hydrogen; Manganese; Manganese-cobalt oxides; Morphology; Nanocomposites; Recovery time; Reduced graphene oxide; Room temperature; Selectivity; Sensors; Spinel
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2023.133348

The design of morphology-based spinel structures has appeared as an effective approach for improving the performance of the sensor in hydrogen gas sensing to facilitate hydrogen economy. In this study, we report a detailed shape selective analysis of four different morphological spinel structures supported on reduced graphene oxide (rGO) as an efficient hydrogen sensor. Our study revealed that the response of manganese-cobalt oxides are strongly depended on the morphology of the system (flower, rod, flakes and sphere) which can be explained by combined effects of surface area, defects generated on the surface and crystallinity. The n-type responses of all native oxides and the composite modified with rGO indicated the formation of n-n heterojunction at their interface. The bare flower-like structure showed higher responses (S% = 6.3) with low response time (17 s) and recovery time (18 s) at higher temperature (160 °C). In comparison, the improved sensing behavior of the composite with highest response (12.77%) and lowest response-recovery time (9 s and 13 s, respectively) at room temperature can be attributed to the higher electrical conductivity of rGO with fast charge carrier mobility. Also, this novel gas sensor demonstrated superior sensitivity, higher stability, and better selectivity against various gaseous mixtures. •MnCo2O4 structures like rod, flower, sphere and flakes were synthesized.•Flower structure showed the higher sensing activity at high temperature (160 °C) due to higher surface defects and larger specific surface area.•rGO-MnCo2O4 flower composite was also synthesized for comparative analysis. The composite sensor showed highest response with ultra-fast response time at room temperature.•Enhanced charge transfer and surface area of rGO is responsible for showing better sensing activity in the composite.