Preparation and NH₃ gas-sensing properties of Ag/β-AgVO₃ nanorods

NH₃ gas sensors operating at room temperature, consisting of Ag nanoparticles decorated β-AgVO₃ nanorods (Ag/β-AgVO₃ NRs), were fabricated via a facile hydrothermal method without the need for a template. The surface characteristics and compositions of Ag/β-AgVO₃ NRs were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Ag nanoparticles, ranging in diameter from approximately 20 to 40 nm, were dispersed on the surface of monoclinic β-AgVO₃ NRs with diameters ranging from 50 to 105 nm and lengths from 0.3 to 1.3 μm. The NH₃ gas sensing properties of Ag/β-AgVO₃ NRs were studied under both dry air and humid conditions at room temperature. Comparative analysis demonstrated that the Ag/β-AgVO₃ NRs exhibited a strong response to NH₃ gas under 70% relative humidity (RH) at room temperature compared to α-AgVO₃ NRs. Specifically, the response of the Ag/β-AgVO₃ NRs to 5 ppm NH₃ increased by 2.25 times as the RH varied from 20% to 80% at room temperature. This enhanced response was attributed to the effects of formation of nanoheterojunctions, nano-metallic Ag activity and the conductivity of NH₄⁺ and OH^- ions induced by the presence of humidity. The room temperature NH₃ gas sensors based on Ag/β-AgVO₃ NRs demonstrated strong responses to low NH₃ concentrations, high selectivity, good reproducibility, and long-term stability, and show promise for the development of low-power and cost-effective NH₃ gas sensors for practical applications even under high humidity.