Highly engineered surface area-based on MOF-derived Co3O4/SnO2 heterostructures: Nanosheet-assembled hierarchical structures towards low-ppm benzene detection

In this study, various SnO 2 and Co 3 O 4 (i.e., Sn/Z, Sn/Co, and Co/Sn) heterostructures with different architectures were prepared utilizing a co-precipitation approach. The underlying properties of the heterostructures, such as crystal structures, surface adsorption states, and chemical states, were evaluated in detail. Surface analyses disclosed the formation of a mixture of nanoparticles and randomly oriented nanoplatelets from various nanostructures. Among the samples, the Co/Sn displayed an extraordinary surface area of 385 m²/g and higher surface defects associated with the oxygen vacancies. The sensing analyses revealed that amongst the sensors, Co/Sn displayed higher sensing characteristics (R g /R a ≈ 13.1) toward 2 ppm benzene at a minimal temperature of 100 °C. Furthermore, the Co/Sn-based sensor demonstrated excellent repeatability and long-term stability for ten (10) weeks, indicating the sensor's reliability. Collective material characterization and testing of the device analyses exhibited that the observed sensing improvement was predominantly attributable to the greater oxygen-adsorption capacity induced by the higher surface area and oxygen vacancies. The fundamentals associated with the sensing mechanism were further deliberated.