Progress in CO Gas Sensing Technologies: Insights into Metal Oxide Nanostructures and Resistance-Based Methods.

The demand for reliable and cost-effective CO gas sensors is escalating due to their extensive applications in various sectors such as food packaging, indoor air quality assessment, and real-time monitoring of anthropogenic CO emissions to mitigate global warming. Nanostructured materials exhibit exceptional properties, including small grain size, controlled morphology, and heterojunction effects, rendering them promising candidates for chemiresistive CO gas sensors. This review article provides an overview of recent advancements in chemiresistive CO gas sensors based on nanostructured semiconducting materials. Specifically, it discusses single oxide structures, metal-decorated oxide nanostructures, and heterostructures, elucidating the correlations between these nanostructures and their CO sensing properties. Additionally, it addresses the challenges and future prospects of chemiresistive CO gas sensors, aiming to provide insights into the ongoing developments in this field.