Polyaniline (PANI)@Au‐TiO ₂ Ternary Composite With Dual Interfacial Junction Modulation for Enhanced Room‐Temperature NH ₃ Detection

Room‐temperature ammonia (NH ₃ ) detection is crucial for environmental safety and human health. In this study, a ternary PANI@Au‐TiO ₂ ammonia‐sensitive composite was synthesized via in situ polymerization of polyaniline (PANI) with simultaneous reduction of chloroauric acid to form Au nanoparticles, followed by ultrasonic compounding with TiO ₂ nanoparticles. The structural and morphological characterization confirmed the uniform distribution of Au and TiO ₂ nanoparticles in the PANI matrix. Gas sensing experiments demonstrated that the PANI@Au‐TiO ₂ sensor exhibited markedly enhanced NH ₃ response, achieving a high sensitivity of 0.0527/ppm compared to PANI, PANI@Au, and PANI‐TiO ₂ counterparts. Moreover, the PANI@Au‐TiO ₂ ternary composite sensor displayed excellent linearity within the NH ₃ concentration range of 3–30 ppm, along with a low detection limit, good repeatability, and high selectivity toward ammonia. The enhanced performance is attributed to the synergistic effects of the p–n heterojunction, Schottky junction, and catalytic activity of Au nanoparticles, which facilitate efficient charge transfer and amplify the interaction with NH ₃ molecules. These findings demonstrate that the hybrid sensing film based on PANI@Au‐TiO ₂ ternary composites exhibits excellent ammonia detection performance at room temperature, thereby offering a promising pathway for the development of advanced ammonia sensors.