Ag-Modified Porous Perovskite-Type LaFeO3 for Efficient Ethanol Detection

Abstract

Perovskite (ABO3) nanosheets with a high carrier mobility have been regarded as the best candidates for gas-sensitive materials arising from their exceptional crystal structure and physical–chemical properties that often exhibit good gas reactivity and stability. Herein, Ag in situ modified porous LaFeO3 nanosheets were synthesized by the simple and efficient graphene oxide (GO)-assisted co-precipitation method which was used for sensitive and selective ethanol detection. The Ag modification ratio was studied, and the best performance was obtained with 5% Ag modification. The Ag/LaFeO3 nanomaterials with high surface areas achieved a sensing response value (Rg/Ra) of 20.9 to 20 ppm ethanol at 180 °C with relatively fast response/recovery times (26/27 s). In addition, they showed significantly high selectivity for ethanol but only a slight response to other interfering gases. The enhanced gas-sensing performance was attributed to the combination of well-designed porous nanomaterials with noble metal sensitization. The new approach is provided for this strategy for the potential application of more P-type ABO3 perovskite-based gas-sensitive devices.

VOC Detections by p-Type Semiconducting Sensors Using Nano-Sized SmFeO3 Particles

“…Zhang et al [ 26 ] reported the response of 221.99 to 100 ppm ethanol using porous Co 3 O 4 with a specific surface area of 28.509 m 2 /g. For perovskite-type oxides, LaFeO 3 has been tested by some research groups [ 27 , 28 ]. Dai et al [ 27 ] prepared LaFeO 3 thin film with the periodic pores of 500 nm in dimension and yielded the response of 14 to 5 ppm ethanol at 450 °C.…”

“…Dai et al [ 27 ] prepared LaFeO 3 thin film with the periodic pores of 500 nm in dimension and yielded the response of 14 to 5 ppm ethanol at 450 °C. Yu et al [ 28 ] prepared the Ag-modified LaFeO 3 with a specific surface area of 16.45 m 2 /g and obtained the response value of 20.9 to 20 ppm ethanol at 180 °C. It is thus obvious that high specific surface area or small particle size of p-type semiconducting oxides is a critical factor for a highly sensitive VOC detection.…”

NiO-Based Gas Sensors for Ethanol Detection: Recent Progress

“…The carriers of the n-type semiconductor increase, so the resistance becomes larger; the carriers of the p-type semiconductor decrease, so the resistance becomes smaller [30][31][32]. In addition to single metal oxides, bimetallic metal oxides have also been used as gas sensing materials in recent years [33], including NiCo 2 O 4 [34], ZnCo 2 O 4 [35], and LaFeO 3 [36]. Even though MOS possess the above advantages, high operating temperature and low selectivity are still their bottlenecks as gas sensors [37].…”

Metal–Organic Framework-Derived LaFeO3@SnO2/Ag p–n Heterojunction Nanostructures for Formaldehyde Detection

“…Also, since the work function of the substrate is lower than that of the noble metal, when they are in contact with each other, free electrons on the surface of the substrate are transferred to the noble metal, which deepens the thickness of the electron depletion layer and creates an additional Schottky potential at the interface base . Yu et al deposited Ag on LaFeO 3 nanosheets by the coprecipitation method and exhibited a high response to ethanol, completing the whole adsorption–desorption process in 53 s.…”

“…Also, since the work function of the substrate is lower than that of the noble metal, when they are in contact with each other, free electrons on the surface of the substrate are transferred to the noble metal, which deepens the thickness of the electron depletion layer and creates an additional Schottky potential at the interface base. 17 Yu et al 18 deposited Ag on LaFeO 3 nanosheets by the coprecipitation method and exhibited a high response to ethanol, completing the whole adsorption−desorption process in 53 s. Perovskite-type LaFeO 3 , as a wide-band oxide semiconductor, is well known because of its unique nanostructure and mixed conductive mode and is widely used in catalysts, 19,20 fuel cells, 21 solar cells, 22 and gas sensors. 23 However, the performance of LaFeO 3 alone is not outstanding, and some modifications are usually needed to improve its performance.…”