Synergistic Effect of PANI/ZnO Composites for High-Sensitivity Ammonia Detection

Ammonia (NH₃) is a toxic gas that must be detected at low concentrations at room temperature. This study synthesized a polyaniline/zinc oxide (PANI/ZnO) composite via an in situ polymerization method, using ZnO prepared via green synthesis from pineapple peel waste. The composite was then applied to a printed circuit board (PCB) substrate with interdigitation electrodes and characterized using XRD, FTIR, and SEM-EDX. The sensor test results showed that PANI/ZnO with 0.3 g ZnO added provided the highest sensitivity of 79% at 4 ppm NH₃, higher than that of pure PANI (61%). The sensor also showed a fast response time (20–29 s), a recovery time of 61–79 s, and good stability in repeated tests. This performance improvement resulted from the synergistic effect of the p–n heterojunction between PANI (p-type) and ZnO (n-type). This study confirms that the environmentally friendly PANI/ZnO composite has excellent potential to be developed as a low-concentration NH₃ sensor at room temperature with sustainable and cost-effective application prospects.