P-type Co3O4 nanoarrays decorated on the surface of n-type flower-like WO3 nanosheets for high-performance gas sensing

[Display omitted] •The cactus-like WO3/Co3O4 p-n junction nanocomposite was synthesized by in-situ growth on the surface of device substrate.•The number of WO3/Co3O4 p-n junctions can be controlled by the reaction time for improving its gas property.•WO3/Co3O4 gas sensor can detect 0.1 ppm triethylamine and show good gas sensing performance. Metal oxide heterostructures are significant materials for developing and improving various toxic gas detection sensors. However, the gas sensing performance, such as response, selectivity, stability and response/recovery time of the sensors, still need to be optimized for practical applications. Low dimensional heterostructures will improve the gas sensing performance remarkably. In this work, hierarchical cactus-like WO3/Co3O4 nanocomposites were directly deposited on the surface of ceramic tube via a simple two-step process. The p-type Co3O4 nanorods array were grown on the surface of n-type WO3 nanosheets by using chemical bath deposition (CBD) and thus many nanoscale p-n junctions were formed which greatly improved the gas sensing performance. A response value (Ra/Rg) of 6.19 to 1 ppm triethylamine (TEA) was achieved at 240 ℃ by the WO3/Co3O4 nanocomposite with the CBD deposition time of 30 min, which is 3 times higher than that of the pure WO3 nanosheets (Sr = 2.02). And the response/recovery time was about 13 s/152 s, which shows good gas sensing performance to TEA.