Pt-modified hollow tube-like polyaniline-based NH₃ sensor

Polyaniline (PANI) has significant applications in room-temperature NH₃ detection due to its unique and reversible doping-dedoping chemical state, stable electrical conductivity and easy and convenient synthesis process. However, pristine PANI still suffers from poor performance in terms of sensitivity, response speed and detection limit. To address issues of low sensitivity and high detection limit, a platinum (Pt)-modified hollow PANI (Pt-PANI) sensor was designed. The Pt-PANI was fabricated by an in-situ sacrificial template method, and Pt-MnO₂ nanowires obtained from hydrothermal combined impregnation methods, utilizing the potential generated during the sacrificial reaction with acid to induce the polymerization of aniline on the nanowires' surfaces. This hollow tube-like structure with the unique inlay of Pt particles provides numerous gas diffusion pathways, facilitating the penetration of the target gas into the internal space, enhancing the utilization of the inner surface and accelerating the electron transfer. Meanwhile, the presence of Pt particles not only forms Schottky junctions that cause large changes in the resistance of the composites, but also catalysis and accelerates the gas sensing reaction between the target gas and the sensitive materials. Gas sensitivity tests revealed that the prepared Pt-PANI-3 gas sensor exhibits a low NH₃ detection limit of 20.3 ppb, along with reproducibility and long-term stability. Compared to pure PANI-sensor, the sensitivity to 20 ppm NH₃ increased by 17 times. This work offers real-time sensing and monitoring of environmental changes, making it highly promising for future applications.