Rh@ZIF-67 nanoparticles for 1-octen-3-ol gas sensor working at room temperature

Selective room-temperature detection of 1-octen-3-ol, a representative fungal volatile organic compound (VOC) associated with food spoilage, remains challenging due to limited adsorption–activation efficiency in conventional sensing materials. Herein, pristine Zeolitic imidazolate framework (ZIF-67) and Rhodium (Rh)-decorated ZIF-67 (Rh@ZIF-67) were developed as chemiresistive sensing materials via a mild solution-based strategy, achieving controlled Rh loadings (0.4–0.6%) while preserving the polyhedral ZIF-67 framework. The crystal structure, surface chemical states, porosity, and morphology were systematically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), and transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (TEM/EDS), confirming that the ZIF-67 framework was preserved and Rh species were successfully anchored on the porous host. At room temperature (25°C), the optimized 0.5%Rh@ZIF-67 sensor exhibits a stable concentration-dependent response over 5–50 ppm, delivering a response of 2.41 at 50 ppm—approximately 15.1 times higher than pristine ZIF-67 (0.16) with response and recovery times of 90 s and 119 s, respectively. The sensor further demonstrates good selectivity, repeatability, and long-term stability over 25 days. Humidity evaluation (30–90%) Relative Humidity (RH) indicates moderate response attenuation attributed to competitive adsorption of water molecules. The enhanced sensing performance is attributed to synergistic adsorption enrichment from porous ZIF-67 combined with Rh-induced catalytic and electronic sensitization, enabling efficient resistance modulation under ambient conditions. This work provides a promising strategy for low-power, selective monitoring of spoilage-related VOC biomarkers in practical storage environments.