Fe2O3-Functionalized CuBi2O4 Surface Heterojunction with Interfacial Modulation for Synergistically Enhanced H2S Sensing in Agricultural Livestock Environments.

Hydrogen sulfide, a typical malodorous pollutant generated during the anaerobic fermentation of manure, can cause severe harm to livestock health and lead to significant economic losses in the aquaculture industry when excessively accumulated. To address this issue, this work developed a highly sensitive ternary oxide sensor for detecting hydrogen sulfide in livestock farming environments. CuBi2O4 (CBO) microspheres assembled from nanoparticles were synthesized via coprecipitation, and iron oxide nanoparticles were subsequently loaded onto the copper bismuthate surface using a hydrothermal method, followed by systematic characterization of the composite material. The results revealed that, compared to pure copper bismuthate, the composite material exhibited significantly reduced response and recovery times of 42 and 37 s, accordingly, with an optimal operating temperature of 215 °C. Due to the incorporation of iron oxide and its narrow bandgap properties, a heterojunction was formed at their interface. This not only resulted in a completely opposite resistance-temperature trend compared to intrinsic copper bismuthate but also effectively suppressed baseline drift and enhanced resistance to humidity. Furthermore, by integrating an optimized Gray Wolf Optimizer (GWO) with multiple models (RF, SVM, and LSTM), high-precision prediction of hydrogen sulfide concentration was achieved. This work proposes a novel strategy to enhance practicality of ternary oxide-based gas sensors in agricultural hydrogen sulfide detection through machine learning.