Highly sensitive and selective nanoengineered PtO2-BNNT heterostructures for ppb level ammonia gas sensing

Ammonia is a frequently used gas in many industrial sectors which is both poisonous and highly corrosive to our human environment. In this study, boron nitride nanotubes (BNNTs) decorated PtO2 nanoparticles (NPs) were used to form a heterojunction for enhancing the room temperature (RT, 28 °C) gas sensing towards dry NH3 gas varying from 0.05-10 ppm. The BNNT was synthesized by boron oxide-assisted chemical vapor deposition (BOCVD). The fabrication of PtO2-BNNT heterostructures was done by RF sputtering of Pt NPs and subsequent deposition of BNNTs using slurry casting and annealing. The existence of BNNT-PtO2 heterostructure was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and energy spectroscopy (EDS) compositional analysis. The integration of PtO2 NPs onto BNNTs provides a synergistic effect, enabling enhanced NH3 sensing capabilities. According to the results, the response time of the PtO2-BNNT sensor to -decorated BNNT sensor to 1 ppm NH3 is 19 s with a low detection limit of 5 ppb NH3 as compared to the pristine PtO2 sensor. Extended modulation of conduction channels by BNNTs functionalized with PtO2 facilitated the large sensor response and selectivity of PtO2–BNNTs sensor with high repeatability, excellent resistance against humidity, and long-term stability.