Fabrication of high performance oxygen sensors using multilayer oxides with high interfacial conductivity

Abstract

The effective enhancement of ionic conductivity for solid oxide electrolytes by manipulating the multilayered hetero-nanostructures has been recognized for more than a decade; however, such fantastic nanostructure has not been applied for practical application yet. Here we fabricated Ce 0.8 Sm 0.1 Nd 0.1 O 2-δ /Al 2 O 3 (SNDC/AO) multilayered electrolyte materials with high oxygen ionic conductivity and explored their applications in oxygen sensors with low operating temperature. The multilayer oxides electrolyte shows a conductivity of 2 orders of magnitude higher than that of traditional yittria-stabilized zirconia (YSZ) ceramics at 400 °C, which endows the sensors with high 2 performances including rapid response (~0.1 s), high sensibility (down to 1 vol.%) and high cycling stability (no performance degradation after 1000 cycles), and most importantly, low operating temperature (200 °C lower relative to the YSZ-based sensors). The excellent performances of our multilayered electrolytes can be attributed to their high interfacial conductivity and low activation energy which might be related to the structurally highly disordered microstructures. This study shows good prospects for the efficient and practical use of multilayered oxide based electrolytes for a range of applications including sensors, oxygen separation, solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). IntroductionOxygen sensors, which can effectively detect oxygen concentration, have been widely used to control the fuels combustion process for applications such as vehicles, aerospace and thermal power generation. 1-4 Effective fuels combustion based on the conventional high-temperature oxygen sensors plays significant roles in increasing energy efficiency and reducing pollutant emission. 5,6 However, to effectively operate sensors at low temperatures such as during the start-up of the cold engines still remains a great challenge. Previous studies showed that miniaturized sensors possess lower operating temperature and excellent performances compared with their macro counterparts. 2,4,7 For example, The sandwich-like microbar structure which consists of two multilayered electrolytes bonded face-to-face without removing substrates is designed to enable an easy alignment of heterointerfaces.The generated fast ion transport pathways, i.e. the heterointerfaces, lead to high ionic conductivity in the current direction of the sensors and thus can reduce the operation temperature. This strategy can successfully overcome the aforementioned key challenge for the practical application of multilayered 13 can be transformed into digital signals of '0' and '1', respectively. Furthermore, it can act as a switch to control the combustion processes in practical applications, including internal combustion engines, industrial boilers and metallurgical heat-treatment furnaces. ConclusionsIn conclusion, we successfully fabricated multilayered solid electrolyte with a unique microbar structure which is facile to be integrated into a micro oxyge...

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