Ammonia Sensing Using Polyaniline Composites by Growth Orientation Control

Polyaniline (PANI) is a promising material for room-temperature ammonia sensing; however, its performance is hindered by its aggregation and slow response and recovery times. To address these challenges, we engineered hollow carbon sphere-supported PANI composites and modulated the PANI growth orientation to enhance the sensing performance. Specifically, we prepared hollow carbon spheres of different sizes (400 nm, 800 nm, and 1.8 μm) and investigated the influence of substrate size on the morphological characteristics of polyaniline and the sensing performance of NH3. Notably, in situ polymerization ensured strong chemical bonding between the PANI molecules and carbon spheres. Under room-temperature conditions, the optimized composite, prepared with hollow carbon spheres with a cavity size of approximately 800 nm, showed a remarkable response of 224.53% along with quick recovery and response times of 25.6 and 59.5 s. Furthermore, it retained 82.97% of the initial response over 21 days, demonstrating long-term stability. The potential of structurally tailored PANI composites for extremely sensitive and reliable NH3 sensors is demonstrated by this work.