Self-templated synthesis of mesoporous Au-ZnO nanospheres for seafood freshness detection

The detection of trimethylamine (TMA), a signature gas for seafood spoilage, is important for real-time assessment of seafood quality. However, traditional detection methods (e.g., gas chromatography) are destructive to samples, expensive and require long time to prepare sample. Herein, mesoporous Au-ZnO nanospheres with high specific surface area (46.8 m²·g⁻¹) and large pore size (12.9 nm) are synthesized and used as a semiconductor metal oxide gas sensor for the detection of TMA. A self-template strategy is developed for the spherical mesoporous sensing materials using Au-Zn-polyphenol hybrids as a precursor. The mesoporous Au-ZnO nanosphere-based gas sensor shows high response of 52.6 towards 10 ppm of TMA at 250 °C. The response is 43 times more than that for mesoporous ZnO spheres without Au modification. The response time is 12 s. The mesoporous Au-ZnO nanospheres synthesized from self-template strategy showed better selectivity and sensitivity than mesoporous Au-ZnO spheres synthesized via a post-modification method. The high sensing performance is ascribed to the homogenous distribution of Au species in the mesoporous ZnO framework. The fabricated TMA sensor from mesoporous Au-ZnO nanospheres can be used to monitor the spoilage process of Carassius auratus. This work demonstrates a reliable method for the facile synthesis of mesoporous noble-metal/semiconductor metal oxide hybrids, which can be potentially applied for the monitoring of fish freshness.