(Plenary) Design Strategies for High-Performance Oxide Semiconductor Gas Sensors

Abstract

Oxide semiconductor gas sensors have been widely used to detect explosive and harmful gases because of their irreplaceable advantages such as high sensitivity, excellent reversibility, simple structure, facile integration, and cost effectiveness, and their applications are being rapidly expanded to environmental monitoring, disease diagnosis from exhaled breath, food quality control, smart farming, and artificial olfaction. In particular, oxide semiconductor chemiresistors and their array can be integrated within smart phones and portable devices, which will open a wide range of new applications through the sensor connection using Internet of Things, multivariate pattern recognition, and machine learning of big gas sensing data in the near future. To date, various nanostructures with high surface area to volume ratio, such as nanoparticles, nanowires, nanosheets have been explored to enhance the gas response and sensing materials have been loaded with noble metal or oxide catalysts for tailoring gas selectivity. However, for demand-based design of high performance gas sensors and artificial olfaction, many issues still remain unsolved, which include the detection of ultralow concentration of analyte gas, highly selective detection of a specific gas, moisture-independent gas sensing, and the establishment of distinctive gas sensing library toward numerous analyte gases as well as complex odors. How can we overcome above challenges? The diversity of gas sensing materials provides a rational solution, which can be accomplished by introducing new sensing materials, designing new nano-archiectures, making new methods to tune the reforming/oxidation of analyte/interference gases, establishing new strategies to maximize/control catalytic activity, and using different ways to control electronic/chemical sensitization. In this presentation, various new, promising and general strategies to design sensitive, selective, and reliable chemiresistors for next-generation gas sensors and artificial olfaction will be suggested, which are as follows: Hollow and hierarchical nanostructures with high gas accessibility for effective and raid gas detection [1]P-type oxide semiconductors with abundant oxygen adsorption, facile redox reaction, and high catalytic activity for detecting new gas species and for expanding the gas sensing materials [2]Multi-valence additives for humidity-independent oxide semiconductor gas sensors [3,4]Catalyst-loaded or catalytic micro-reactors such as yolk-shell spheres and multiroom-structured spheres for highly selective detection of aromatic compounds via the reforming of less-reactive gases into more reactive species [5]Bilayer sensors consisting of sensing layer and nanoscale catalytic overlayer for separating catalytic and sensing reactions as well as for tailoring gas selectivity and response without limiting the gas transport [6]Hetero-nanostructures consisting of two different materials with dissimilar catalytic activity and work function for enhancing catalytic activity and for promoting electronic sensitization via the charge transfer across hetero-interface [7]Semiconducting multinary oxides consisting of two or more catalytic components [8].Monolayer oxide nanofiber sensor with tailored exposure of catalytic electrode for controlling gas selectivity [9] References [1] J.-H. 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