Enhanced room-temperature detection of H₂S using in₂O₃–PANI composite: role of synergistic p–n junction effects

In this work, a hybrid H₂S gas sensor based on polyaniline (PANI) and indium oxide (In₂O₃) was developed and systematically characterized to explore synergistic effects in gas sensing. While pure PANI showed strong response at elevated temperatures and In₂O₃ exhibited limited sensitivity, their composite demonstrated a remarkable enhancement, particularly at room temperature. The 1:1 In₂O₃–PANI composite achieved a maximum sensitivity of 84.24% at 25 °C, significantly outperforming both individual components. This superior performance is attributed to the formation of a p–n heterojunction at the polymer–metal oxide interface, which improves charge transfer and facilitates efficient gas adsorption and desorption. Structural and BET analyses confirmed increased surface area and porosity in the composite, contributing to faster response and recovery dynamics. These findings highlight the potential of polymer–metal oxide hybrids in designing low-power, ambient-temperature gas sensors for real-time environmental monitoring and industrial safety. The study underscores compositional engineering as a key approach in next-generation sensor development.