Promoted effect of PANI on the preferential oxidation of CO in the presence of H2 over Au/TiO2 under visible light irradiation

A Polyaniline (PANI) assembled Au/TiO2 catalyst (Au/TiO2–PANI) was prepared by deposition–precipitation with the assistance of in-situ polymerization assistance, and was performed for oxidizing CO in H2-rich stream under visible light irradiation. It is found that the as-prepared Au/TiO2–PANI exhibited a higher activity of CO preferential oxidation (PROX) than the Au/TiO2 without PANI decoration at room temperature under visible light irradiation. Based on the results of structure characterization, photo-absorbance, photo-electrochemical, electron paramagnetic resonance, and adsorbing CO and H2 of Au/TiO2–PANI, it is proposed that the photo-excited electrons of PANI could transfer to TiO2 accompanied by suppressing the transfer of excited electrons induced by the localized surface plasmon resonance of Au nanoparticles to TiO2, resulting in the increases in surface electron densities of both Au and TiO2 sites. This will promote the activation of CO adsorbed at Au sites and the formation of O2− species at TiO2 sites, and then the oxidation of CO. Meanwhile, the protonation of N atoms in PANI could cause a spillover of the dissociative H at Au sites into PANI, resulting in the suppression of H2 oxidation.