Changchun University of Science and Technology's Professor Dong Xiangting & Associate Professor Li Dan: Rare Earth Ion-Modified MoO₃ Quasi-Core-Shell Nanorods for Triethylamine Monitoring and Fish Spoilage Assessment

Triethylamine (TEA) is a toxic organic gas commonly found in spoiled or decaying seafood, posing significant risks to human health and the environment. Prolonged exposure to TEA may cause damage to respiratory mucosa and lead to various diseases, including pulmonary edema. Additionally, detecting trace amounts of TEA can serve as an indicator of seafood freshness.Currently, conventional TEA detection methods primarily rely on instruments such as gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). However, their practical applications are often limited by large size, poor portability, long detection cycles, and high costs. In contrast, gas sensors have emerged as a promising alternative due to their compact size, rapid response, and cost-effectiveness.Given these advantages, the development of high-performance gas sensors with enhanced TEA sensitivity holds substantial value. Such sensors could enable real-time monitoring of food freshness while providing an efficient and portable solution for environmental and industrial safety applications.

Recently, the research team led by Professor Dong Xiangting and Associate Professor Li Dan from Changchun University of Science and Technology published their latest research findings titled "Rare-earth ions (Pr³⁺, Dy³⁺, Y³⁺, Er³⁺, Lu³⁺) modified MoO₃ quasi-core-shell nanorods for triethylamine monitor and fish decayed level assessment" in the journal Chemical Engineering Journal.

The researchers successfully synthesized MoO₃:x%RE³⁺ (RE³⁺=Pr³⁺, Dy³⁺, Y³⁺, Er³⁺, Lu³⁺; x=0, 0.5, 1, 3, 5) quasi-core-shell nanorods through electrospinning combined with oxidative calcination, and further fabricated them into gas sensors. After rare earth ion doping, all MoO₃:1%RE³⁺ gas sensors showed higher response values to TEA than pure MoO₃. The MoO₃:1%Pr³⁺ quasi-core-shell nanorod gas sensor exhibited excellent gas sensing performance, with a response value 12.3 times higher than that of the MoO₃ sensor, along with high selectivity, fast response/recovery times, and remarkable humidity resistance.By testing the TEA content produced by spoiled seafood under different storage temperatures and humidity conditions at various storage times, the feasibility of using MoO₃:1%Pr³⁺ one-dimensional nanorod gas sensors for seafood freshness assessment was verified. Figure 1 shows the preparation flowchart of MoO₃:x%RE³⁺ quasi-core-shell nanorods. The prepared samples exhibited quasi-core-shell nanorod morphology (Figure 2).This work provides an innovative strategy for designing and constructing high-performance gas sensors for TEA detection, and also has significant implications for the application of rare earth materials in gas sensing. 

Figure 1: Preparation flowchart of MoO₃:x%RE³⁺ quasi-core-shell nanorods.

Figure 2: TEM images (a-d), SAED pattern (e), and HRTEM image (f) of MoO₃:1%Pr³⁺ quasi-core-shell nanorods.

Figure 3: Response values of MoO₃ and MoO₃:x%Pr³⁺ (a), MoO₃:x%Dy³⁺ (b), MoO₃:x%Y³⁺ (c), MoO₃:x%Er³⁺ (d), MoO₃:x%Lu³⁺ (e), MoO₃:1%RE³⁺ (RE³⁺=Pr³⁺, Dy³⁺, Y³⁺, Er³⁺, Lu³⁺) (f) quasi-core-shell nanorod gas sensors to 100 ppm TEA at different working temperatures, and the resistance of MoO₃ and MoO₃:1%RE³⁺ in air at different working temperatures (g).

After doping MoO₃ with rare earth ions, the response values of gas sensors to TEA were all improved. When the rare earth ion doping amount was 1%, the MoO₃:1%RE³⁺ gas sensors showed higher response values to TEA, mainly due to the effects of active sites and defects. Among them, the MoO₃:1%Pr³⁺ quasi-core-shell nanorod gas sensor reached its maximum response value of 137.32 at 270°C (Figure 3). Compared with other gases, all gas sensors showed higher response values to TEA (Figure 4). Compared with other samples, MoO₃:1%Pr³⁺ demonstrated better gas sensing performance for TEA.

Figure 4: Response values of MoO₃ and MoO₃:x%RE³⁺ quasi-core-shell nanorod gas sensors to 100 ppm different gases at optimal working temperatures.

Using 20g of fresh fish meat (mirror carp), the practicality of MoO₃:1%Pr³⁺ quasi-core-shell nanorod gas sensors for volatile gas detection was tested to assess fish freshness, indicating that MoO₃:1%Pr³⁺ one-dimensional nanorod gas sensors have great potential in detecting fish spoilage levels (Figure 5).

Figure 5: Photographs of fresh fish meat (a) and fish meat stored at room temperature for 9 hours (b); dynamic response curves (c-f) of MoO₃:1%Pr³⁺ quasi-core-shell nanorod gas sensors to gases released from 20g fish meat at different storage times (6, 7, 8, 9 h).

Zhao Xiang, a graduate student at Changchun University of Science and Technology, is the first author of this research achievement. The design concept and preparation technology play an important role in developing MOS-based one-dimensional quasi-core-shell nanomaterials, and the prepared gas sensors have good application prospects in detecting fish spoilage levels.

Paper link: https://doi.org/10.1016/j.cej.2025.162690