Detection of volatile organic compounds (VOCs) at room temperature (RT) currently remains a challenge for metal oxide semiconductor (MOS) gas sensors. Herein, for the first time, we report on the utilization of porous SnO2 thin films for RT detection of VOCs by defect engineering of oxygen vacancies. The oxygen vacancies in the three-dimensional-ordered SnO2 thin films, prepared by a colloidal template method, can be readily manipulated by thermal annealing at different temperatures. It is found that oxygen vacancies play an important role in the RT sensing performances, which successfully enables the sensor to respond to triethylamine (TEA) with an ultrahigh response, for example, 150.5-10 ppm TEA in a highly selective manner. In addition, the sensor based on oxygen vacancy-rich SnO2 thin films delivers a fast response and recovery speed (53 and 120 s), which can be further shortened to 10 and 36 s by elevating the working temperature to 120 °C. Notably, a low detection limit of 110 ppb has been obtained at RT. The overall performances surpass most previous reports on TEA detection at RT. The outstanding sensing properties can be attributed to the porous structure with abundant oxygen vacancies, which can improve the adsorption of molecules. The oxygen vacancy engineering strategy and the on-chip fabrication of porous MOS thin film sensing layers deliver great potential for creating high-performance RT sensors.

Oxygen Vacancies Enabled Porous SnO2 Thin Films for Highly Sensitive Detection of Triethylamine at Room Temperature.

A review on WO3 based gas sensors: Morphology control and enhanced sensing properties

Diversiform metal oxide-based hybrid nanostructures for gas sensing with versatile prospects

The development of gas sensor that is capable of detecting ppb-level detection of acetone and possesses high response toward low-concentration acetone remains a great challenge. Herein, we present the construction of the W18O49/Ti3C2Tx composites based on the in situ grown of the 1D W18O49 nanorods (NRs) on the surfaces of the 2D Ti3C2Tx Mxene sheets via a facile solvothermal process. The W18O49/Ti3C2Tx composites exhibit high response to low concentration acetone (11.6 to 20 ppm acetone), ideal selectivity, long-term stability, very low limit of detection of 170 ppb acetone, and fast response and recover rates (5.6/6 s to 170 ppb acetone). Compared to the W18O49 NRs and Ti3C2Tx sheets, the W18O49/Ti3C2Tx composites show significant improvement on the acetone-sensing performance, which can be ascribed to the homogeneous distribution of the W18O49 NRs on the Ti3C2Tx surface, the removal of the fluorine-containing groups from the Ti3C2Tx after the solvothermal process, and the synergistic interfacial interactions between the W18O49 NRs and the Ti3C2Tx sheets. The synthesis of the 1D/2D W18O49/Ti3C2Tx Mxene composites provides a new avenue to develop other promising hybrids for acetone sensing.

W18O49/Ti3C2Tx Mxene nanocomposites for highly sensitive acetone gas sensor with low detection limit

Plasma-induced oxygen vacancies enabled ultrathin ZnO films for highly sensitive detection of triethylamine.

Superior triethylamine detection at room temperature by {-112} faceted WO3 gas sensor.

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.

Lele Yang

Papers

Superior triethylamine detection at room temperature by {-112} faceted WO3 gas sensor.

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

Enhanced gas sensing properties to NO 2 of SnO 2 /rGO nanocomposites synthesized by microwave-assisted gas-liquid interfacial method