Gas sensitivity study of polypyrrole/WO3 hybrid materials to H2S

Polypyrrole (PPy) and WO3 were prepared by chemical oxidation polymerization and emulsion method, respectively. PPy/WO3 hybrid materials with different PPy mass percent were prepared by mechanical mixing. WO3 and PPy/WO3 hybrids were characterized by XRD, SEM and HRTEM, and the sensitivity studies of PPy, WO3 and PPy/WO3 to toxic gases NH3, H2S, NOx were also carried out. It was found that the particle size of WO3 was about 29 nm, and PPy/WO3 was about 50–100 nm. Gas sensitivity tests showed that when operated at 90 °C, PPy/WO3 hybrids had better reversibility to H2S than PPy higher sensitivity and selectivity to H2S than WO3. PPy/WO3 materials had short response–recovery time to H2S and their sensitivities had linear relationship with the concentration of H2S. The sensitive mechanism of PPy/WO3 materials to H2S may be the co-effect of proton doping process and the n-type semiconductor's effect.