Microhotplate gas sensors incorporated with Al electrodes and 3D hierarchical structured PdO/PdO2-SnO2:Sb materials for sensitive VOC detection

High-performance, low-power microhotplate (MHP) gas sensors loaded with 3D hierarchical structured PdO/PdO 2 -SnO 2 :Sb materials on a pair of Al gas sensing electrodes were fabricated through advanced high-accuracy electrohydrodynamic printing method. The PdO/PdO 2 -SnO 2 :Sb materials with various PdO/PdO 2 concentrations were initially synthesized via a mild and simple hydrothermal reaction. Their micromorphology and chemical composition were characterized by SEM, XRD, TEM, and XPS, which proved the successful synthesis. The gas sensing performance of the sensors to benzene, ethanol, acetone, formaldehyde, and ethanol-acetone mixed gas (volume ratio 1:1) was tested. The sensing property of the materials is regulated with different content of PdO/PdO 2 . The identification of the VOCs is realized by two-step principal component analysis (PCA). Simulation calculations on the I–V characteristic of the MHP gas sensors reveal that carriers have to get through Al 2 O 3 barriers by Poole-Frenkel emission, which significantly affects the carrier conduction as well as the gas sensing properties. The gas sensing mechanism is analyzed from the aspects of gas sensing material and electrodes.