High-sensitivity NH3 gas detection at room temperature using In2O3 nanoparticles-modified VO2(B) nanorods heterojunction

[Display omitted] •As a narrow-band semiconductor, VO2(B) is capable of detecting NH3 at room temperature.•The modification of VO2(B) by In2O3 improved the sensing performance of VO2(B) for NH3 at room temperature.•The sensitivity of the sample obtained by annealing at 400 ℃ to 100 ppm NH3 under room temperature conditions was 92.•The material has good stability and selectivity.•The sensing mechanism was explained according to XPS and other tests. In2O3 nanoparticles-modified VO2(B) nanorods heterojunction was proposed to improve the NH3 sensing performance at room temperature (25 ℃). VO2(B) nanorods were prepared by hydrothermal method and modified with In2O3 nanoparticles through chemical deposition and annealing. The effect of annealing temperature on microstructure and NH3 sensing performance was investigated. The morphology and crystal structure of the composite structure were characterized using SEM, TEM, and XRD. The results show that In2O3 nanoparticles with a diameter of 20–25 nm were uniformly distributed on the surface of VO2(B) nanorods when the annealing temperature was 400 ℃. Room temperature NH3 sensing performance was tested for six concentrations (1–100 ppm). Results showed that samples annealed at 400 ℃ exhibited the highest sensitivity, with a response value of up to 92 for 100 ppm NH3. This excellent sensing performance can be attributed to the excitation of electrons in narrow bandgap semiconductor VO2(B) at room temperature and the surface modification by In2O3 nanoparticles, which promote the adsorption of surface oxygen. Density functional theory indicated the composite structure has lower NH3 adsorption energy compared to VO2(B) and In2O3. A possible sensing mechanism combined heterojunction effect with hydroxylization effect was proposed to explain the sensing enhancement for composite structure.