Role of Mn3+/Mn4+ redox-coupled oxygen vacancy modulation in SnO2 nanoarchitectures for ultrasensitive acetone detection

Acetone (CH 3 COCH 3 ) is a ubiquitous volatile organic compound in industrial and laboratory settings; however, its high volatility and toxicity necessitate advanced monitoring to ensure human health and occupational safety. In this work, we report a highly sensitive and selective sensor based on Mn 2 O 3 -decorated SnO 2 nanorods (MSNRs) fabricated via a sequential glancing angle deposition (GLAD) technique. By systematically tailoring the Mn 2 O 3 decoration thickness (0, 1, 3, and 5 nm), we achieved a high response of ≈204.7 toward 5 ppm CH 3 COCH 3 at 300 °C, representing a ≈ 227.3-fold enhancement compared to conventional SnO 2 thin films. The sensor demonstrates exceptional selectivity against six target gases, an ultralow theoretical detection limit of 1.5 ppb, and remarkable repeatability (CV ≈ 2.2%), even under 80% relative humidity. Surface chemical analysis indicates that the optimized Mn 4+ /(Mn 3+ +Mn 4+ ) ratio and oxygen vacancy-related components promote reactive oxygen species (ROS) generation and dynamic surface redox processes, thereby facilitating efficient interfacial reactions with target gases. These synergistic structural and electronic effects demonstrate the potential of MSNRs as a versatile platform for trace-level acetone detection in airborne pollutant monitoring.