Preparation of p-LaFeO₃/n-Fe₂O₃ Heterojunction Composites by One-Step Hydrothermal Method and Gas Sensing Properties for Acetone

Perovskite LaFeO ₃ materials have received increasing attention in volatile organic compound (VOC) gas detection due to their unique crystal structure and excellent physicochemical properties. However, achieving high sensitivity with a low limit of detection at low temperature is still an important research topic. In this work, p-LaFeO ₃ /n-Fe ₂ O ₃ composites were prepared by a simple one-step hydrothermal method for the detection of acetone gas. Various characterizations showed that the LaFeO ₃ /Fe ₂ O ₃ composites were successfully synthesized. The test results showed that the LaFeO ₃ /Fe ₂ O ₃ composites have more excellent gas sensing properties than acetone compared with pure LaFeO ₃ material. The response of the LaFeO ₃ /Fe ₂ O ₃ sensor to 10 ppm acetone (23.5) at 210 °C is almost five times larger than that of the pure LaFeO ₃ material. In addition, the LaFeO ₃ /Fe ₂ O ₃ sensor has a low limit of detection (100 ppb), good long-term stability, and selectivity. The enhanced acetone sensing performance can be ascribed to changes in the electronic structure and surface properties caused by heterojunctions, as well as to the synergistic effect formed between the two components. This work provides a simple synthetic strategy to enhance the acetone gas sensing performance of perovskite-type LaFeO ₃ , which has promising applications in industrial production and healthcare.