Gas sensing properties of MoO3 nanoparticles synthesized by solvothermal method

MoO3 nanoparticles were prepared by thermally oxidizing the MoO2 nano-crystallites synthesized by solvothermal reaction, and their gas sensing properties were investigated. Ethanol and water mixed solvents were used in the solvothermal synthesis, and it was observed that the phase, size, and morphology of the products were strongly dependent on the composition of solvents. Well-crystallized and spherical MoO2 nano-crystallites (~20 nm) were obtained in the mixed solvent (water:ethanol = 40:10 in vol), and subsequent heat treatment at 450 °C produced the well-separated, slightly elongated MoO3 nano-particles of ~100 nm. The nano-particle MoO3 gas sensor responded to both oxidizing and reducing gases, but it exhibited the extremely high gas response toward H2S with a short response time (<10 s). In particular, the magnitude of gas response of nano-particle MoO3 gas sensor was about 10 times higher than that of micron-sized commercial MoO3 powder sensor at 20 ppm H2S.