PdRh bimetallic-loaded α-Fe2O3 nanospindles with Ppb-limit of 3-hydroxy-2-butanone biomarker detection: Particle dimension regulation and oxygen spillover effect

Biomarkers detection of foodborne pathogens through gas sensors provides a promising method to ensure food safety. However, rapidly and accurately identifying ultra-low concentration bacterial biomarkers is still an urgent task. In this study, PdRh bimetallic-loaded α-Fe 2 O 3 nanospindles with sufficient exposed surface and high surface activity are designed to achieve sensitive detection of the Listeria monocytogene biomarker s : 3-hydroxy-2-butanone. α-Fe 2 O 3 nanospindles with high exposure surfaces were prepared by modulating the axial diameter ratio. Then PdRh bimetals were uniformly introduced to regulate the surface activity of α-Fe 2 O 3 nanospindles. Compared to pure Fe 2 O 3 , the result 1.5 wt% PdRh-Fe 2 O 3 nanospindle exhibits significantly improved sensitivity and selectivity in detecting 3-hydroxy-2-butanone, characterized by a reduced operating temperature from 240°C to 150 °C, high sensitivity (R a /R g  = 148.4, 50 ppm), impressive response/recovery time (7/10 s), low detection limit (200 ppb), notable selectivity, and great stability over a test period exceeding 30 days. Mechanism studies through ex/in-situ characterization and density functional theory calculations (DFT) reveal that the dramatic sensing performance advancement is mainly due to the morphology optimization, bimetallic activation, and their synergistic effects, leading to the increased surface active species, enhanced oxygen mobility, and the reduced activation energy. Furthermore, high-sensitivity detection of Listeria monocytogenes in actual samples is also achieved by using 1.5 wt% PdRh-Fe 2 O 3 nanoneedles-based sensor, indicating its significant potential for non-destructive testing applications in the food industry and opening new avenues for the rapid detection of Listeria monocytogenes .