Present and Future of Emerging Catalysts in Gas Sensors for Breath Analysis

To rationalize the noninvasive disease diagnosis by breath analysis, developing a high-performance gas sensor with exceptional sensitivity and selectivity is important to detect trace biomarkers in complex exhaled breath under harsh conditions. Among the various technological innovations, catalyst design and synthesis techniques are the foremost challenges, because gas sensing properties are predominantly determined by surface chemical reactions governed by catalytic activities. Conventional nanoparticle-based catalysts, with their simple structural features, have technical limitations in achieving the requirement for accurate breath analysis. Innovative strategies have been pursued to synthesize unconventional catalyst types with enhanced catalytic capabilities. This Perspective provides a comprehensive overview of recent advancements in catalyst technology for chemiresistive-type gas sensors used in breath analysis. It discusses various emerging catalysts, such as doping catalysts, single-atom catalysts (SACs), bimetallic alloy catalysts, high-entropy alloy (HEA) catalysts, exsolution catalysts, and catalytic filter membranes, along with their unique chemical activation mechanisms that enhance gas sensing properties for detecting target biomarkers in exhaled breath. The review also explores novel strategies for catalyst design, including computational prediction, advanced synthesis techniques, and the integration of sensor arrays with artificial intelligence (AI) to improve diagnostic reliability. By highlighting the crucial role of these emerging catalysts, this review provides valuable insights into the catalytic, synthetic, and analytical aspects that are essential for advancing breath analysis technology.