Low Temperature Ammonia Sensor with Giant Sensitivity and Selectivity based on W@WO2.92 Internal Ohmic Contact Core-Shell Nanostructures

Ammonia (NH₃) detection is crucial for both harnessing hydrogen energy and safeguarding public health. However, the NH₃ sensors based on semiconductors is currently constrained by their necessity to operate at elevated temperatures and their limited ability to distinguish NH₃ from other gases. In this study, the high oxygen vacancy W@WO_2.92 core-shell nanostructures have been synthesized by pulsed laser ablation in water. The gas sensors based on W@WO_2.92 nanoparticles response to NH₃ with high sensitivity (|R_a-R_g|/R_a=72.6%@100 ppm, R_a and R_g represent the resistance of the material when exposed to air and the test gas, respectively.) at room temperature with detection limit of 730 ppb. Additionally, the response to NH₃ can achieve 55% even at 5℃, which plays a great role in timely detection of NH₃ during low temperature transportation. Furthermore, the sensors reveal outstanding selectivity toward NH₃ in the presence of 11 other potential interfering gases. This research presents a groundbreaking strategy, holding significant potential for the development of high-performance NH₃ sensors that operate efficiently at low temperatures.