Porous nanostructured GdFeO₃ perovskite oxides and their gas response performance to NO_x

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Gas sensing characteristics of rare-earth-based orthoferrite (GdFeO<SUB>3</SUB>) mesoporous nanostructures were prepared by a facile one-step hydrothermal process. The structural analyses of the obtained materials showed sphere, leaf and flower-like nanostructured architectures. Further, the chemiresistive gas-response properties of the GdFeO<SUB>3</SUB> nanostructure were investigated with various combustible gases, such as nitric oxide (NO), nitrogen dioxide (NO<SUB>2</SUB>), carbon monoxide (CO), ammonia (NH<SUB>3</SUB>), hydrogen sulfide (H<SUB>2</SUB>S), formaldehyde (HCHO), ethanol (C<SUB>2</SUB>H<SUB>5</SUB>OH) and gasoline, at different operating temperatures. The sphere-like GdFeO<SUB>3</SUB> nanostructure shows a significantly high resistance variation to NO compared with the other architectures, exhibits a high response (91%) when exposed to 100 ppm NO, and detects a level as low as 2 ppm (7%) at an optimum operating temperature of 140 °C. The GdFeO<SUB>3</SUB> nanostructure shows an excellent stability and repeatability after successive repeated cycles with a fast response and recovery time when exposed to 100 ppm NO gas. The superior response and excellent selectivity of the perovskite GdFeO<SUB>3</SUB> nanostructure are due to its higher catalytic activity, large surface area, oxygen deficiency, mesoporosity, and peculiar morphology. The response mechanism of NO on the GdFeO<SUB>3</SUB> nanostructured surface is also discussed in detail.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mesoporous rare-earth orthoferrite (GdFeO<SUB>3</SUB>) nanostructures were prepared by a facile one-step hydrothermal process. </LI> <LI> Structural effects of GdFeO<SUB>3</SUB> nanostructure on NO<SUB>x</SUB> gas-response properties were systematically investigated. </LI> <LI> Mesosphere-like GdFeO<SUB>3</SUB> nanostructure exhibited the best gas-response characteristics to nitric oxide (NO) at 140 °C. </LI> <LI> NO gas-response mechanism of GdFeO<SUB>3</SUB> nanostructure was discussed. </LI> </UL> </P>