Optimal construction and gas sensing properties of SnO2@TiO2 heterostructured nanorods

Network-structured TiO2 nanorods were synthesized via a facile hydrothermal method and decorated with SnO2 nanoparticles by a solution-coating method to form SnO2@TiO2 nanorods (STNRs). The structural characterization indicated that SnO2 loading amount has a great effect on the microstructure and morphology of TiO2 backbone. The diameter of TiO2 nanorods increased from about 160 nm to 190 nm after decoration by SnO2 nanoparticles with approximately 7 nm in diameter. The static gas sensing tests revealed that the highest response of 15.4 was achieved for the 1.0 STNRs sample to 500 ppm H2 at 100 °C, and the response time and recovery time were 11 s and 132 s, respectively. Gas sensors based on SnO2@TiO2 heterostructured nanorods also showed excellent reproducibility and selectivity to H2. The enhanced sensing mechanism of STNRs to H2 is discussed in relation to the modulation of conduction channel, potential barrier, and chemical/electron sensitization.