Ultrafast and ppb‑level acetoin detection using Pd‑loaded Cd2GeO4 chemiresistive sensors for food spoilage evaluation

Detection of 3-hydroxy-2-butanone (acetoin), a characteristic volatile metabolite of Listeria monocytogenes (LM) , represents a promising non-invasive strategy for monitoring contamination levels of foodborne pathogens in food. However, current sensing materials suffer from poor selectivity and insufficient sensitivity at trace concentrations. Herein, a series of Pd-loaded Cd 2 GeO 4 (Pd/CGO) chemiresistive gas sensors that achieves highly selective and sensitive acetoin detection was reported. Among them, the 0.5 wt% Pd/CGO-based sensor exhibits a high response, with an ultrafast response time and a detection limit as low as 10 ppb. The sensor also demonstrates excellent selectivity over common interfering gases, good reproducibility, and robust long-term stability. Mechanistic investigations combining O 2 -TPD, XPS, and DFT calculations reveal that Pd loading not only increases the proportion of chemisorbed oxygen species on the CGO surface, which enhances the overall sensing response, but also serves as new active sites. This work demonstrates that rational Pd modification combined with dual-site engineering offers a promising paradigm for designing high-performance metal oxide gas sensors for pathogen biomarker detection in food.