Hierarchical Porous Rod-Like In2S3/In2O3 Structures for Trimethylamine Detection

Abstract

Trimethylamine (TMA), a volatile gas possessing a strong, pungent odor, is widely recognized as an indicator for evaluating fish freshness. Despite the importance of TMA detection, the development of sensors that simultaneously possess high sensitivity, fast response kinetics, selectivity, and low-temperature operation remains a challenge. To address this issue, this work presents a novel gas-sensing material composed of porous, rod-like In₂S₃/ In₂O₃ structures, synthesized via an in-situ sulfurization process. By precisely modulating the sulfurization state of In₂O₃ through the adjustment of thioacetamide concentrations, the material's structural and compositional properties were optimized for enhanced sensing performance. Experimental results demonstrate that sulfur incorporation significantly improves sensor capabilities, owing to the synergistic effects of the In₂S₃/ In₂O₃ heterojunction, the enhanced adsorption capacity for oxygen molecules, and the distinctive one-dimensional and porous architecture. Notably, the sensor with an S/In molar ratio of 1/3 exhibited exceptional TMA detection at 150 °C, with the highest response values (2.17 for 0.1 ppm and 8.17 for 10 ppm), rapid response/recovery times, excellent selectivity, and a low detection limit of 0.05 ppm. Moreover, the sensor demonstrated outstanding reproducibility and long-term stability, highlighting its potential for practical applications in seafood freshness monitoring.