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 m(2).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 nanospherebased gas sensor shows high response of 52.6 towards 10 ppm of TMA at 250 degrees C. The response is 43 times more than that for mesoporous ZnO spheres without Au modification. The response time is 12 s. The mesoporous AuZnO 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.