Precise Optical Fiber-Based Ammonia Sensor Using CdS Quantum Dots Decorated with ZnO at Heterointerface.

Ammonia (NH₃) sensing is crucial for environmental safety, necessitating the development of efficient NH₃ sensors. In this study, an efficient NH₃ sensor based on CdS quantum dots (QDs) decorated with ZnO (CdS/ZnO) covering optical fiber was successfully fabricated. The CdS/ZnO was first synthesized by a hydrothermal method, featuring an n-n heterojunction in the composite material. The optimal sensor with 10 wt% CdS QDs exhibits efficient performance, with a response sensitivity of 0.9 × 10⁻³ dB/ppm and R² = 0.9858. Additionally, it demonstrates excellent selectivity and repeatability. Mechanistic insights for the NH₃ sensor were elucidated through X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy. These results confirm that the enhancement in NH₃ sensing performance is attributed to the formation of well-defined n-n heterojunctions. This study contributes to the advancement of gas-sensing technology, particularly in the detection of harmful gases, such as NH₃. [ABSTRACT FROM AUTHOR]