Highly sensitive and selective gas sensors based on 2D/3D Bi2MoO6 micro-nano composites for trimethylamine biomarker detection

Abstract

Metal oxide semiconductor based gas sensors have been verified to be an effective way for food quality detection. However, the high operating temperature, insufficient sensitivity, and selectivity limit their wide application. Herein, one simplest Aurivillius oxide, Bi2MoO6 microspheres and a series of exfoliated g-C3N4/Bi2MoO6 hetero-composites were developed using a facile solvothermal route, which are used to detect trimethylamine (TMA, a volatile biomarker of fish freshness) at 22 °C. The introduction of E-g-C3N4 contributes to modulating the grain size of Bi2MoO6 and tuning the Bi/Mo cations valence states, thus improving the surface reactivity and electron transfer efficiency. Benefiting from the synergetic engineering of 2D/3D micro-nanostructure, crystal defects, and well-defined n-n heterojunctions, 1 wt% E-g-C3N4/Bi2MoO6 attained superior TMA sensing performance at 22 °C, including the highest response (Ra/Rg = 10.6 @ 20 ppm) and accelerated response/recovery speed, fine selectivity, and low detection limit (1.3 ppm), which is far satisfied with the detection requirement. Furthermore, the comprehensive evaluation based on the fish color and tissue state, sensing characteristics, PCA, and pH testing results reveal the fabricated TMA sensor can achieve rapid and non-destructive fish freshness detection. This work provides insights into designing low-power consumption chemiresistive gas sensors and devices with valid practicality.