Advancements in Nanostructured Functional Constituent Materials for Gas Sensing Applications: A Comprehensive Review

The unique properties of nanostructures, such as their high surface-to-volume ratio, tunable physical and chemical characteristics, and enhanced sensitivity, are critical for advancing gas detection technologies. Therefore, this comprehensive review explores the recent advancements in nanostructured materials, emphasizing their pivotal role in enhancing gas sensing performance. A key focus of this review is metal oxide-based gas sensors, and the impact of synthesis methods and (micro)structural properties on sensor performance is thoroughly examined. By segmenting the discussion into 1D nanostructured materials, including different metal oxides, the review provides a broad yet detailed perspective on how different functional materials contribute to gas sensing efficiency. From a performance standpoint, this review highlights critical sensing parameters, including gas detection mechanisms, response times, selectivity, stability, and operating conditions. High-end detection values may reach around a few ppb for most gases. Beyond evaluating current advancements, this review also addresses existing challenges and future research directions, particularly in scalability, long-term sensor stability, low-temperature operation, and integration into real-world applications. By providing a comprehensive and up-to-date analysis, this review serves as a valuable resource for researchers and engineers, offering insights that can drive the next generation of high-performance, reliable, and selective gas sensors.