Active-Site Engineering Enhanced PdRu Bimetallic Modified Hierarchical Mesoporous In2O3 Nanoflowers for Highly Efficient Assessment of Seafood Freshness.

Highly sensitive detection of trimethylamine (TMA) concentration in complex monitoring environments is a pivotal technology for food freshness assessment. Herein, through an active-site engineering strategy, PdRu-modified hierarchical In2O3 nanoflowers were successfully prepared by self-assembly of mesoporous nanosheets. The 3D interconnected pore system significantly promotes the diffusion and mass transfer of TMA, while notably enhancing the interfacial collision efficiency in gas-sensitive reactions. The PdRu/In2O3-1.0-based sensor exhibits a sensitivity of 71.9 at 50 ppm, with a detection limit of 200 ppb, while optimizing the operating temperature range from 200°C to 140°C. Simultaneously, machine learning-based analysis confirms the high selectivity, enabling it to identify TMA in ammonia-containing binary mixtures with an accuracy quantified at 99.3%. Furthermore, density functional theory calculations combined with in situ/ex situ characterizations revealed that bimetallic oxygen spillover effects optimize oxygen transfer kinetics, reduce the activation energy barrier, and collectively enhance the trimethylamine adsorption energy (ΔEads = -0.51 eV) through orbital hybridization and charge redistribution mechanisms. Leveraging the advanced sensing strategy, the wireless portable sensing system is engineered for the rapid and non-destructive evaluation of seafood freshness, enabling quality detection and cloud data transmission throughout the entire industry chain.