Synthesis and characterization of AgxOAgxO, and hydrogen production from methanol photodecomposition over the mixture of AgxOAgxO and TiO2TiO2

This study focused on the production of hydrogen from the methanol destruction in a liquid photocatalytic system that comprised a mixture of AgxOAgxO and TiO2TiO2 (P-25, Degussa). The nanometer particles of AgxOAgxO were obtained by a conventional sol–gel method in the presence of tetraethylammonium hydroxide using thermal treatment at 50, 100, 150, 200, 250, and 300∘C to attain various silver oxide forms. The 38.0∘38.0∘ and 43.0∘43.0∘ peaks, which were assigned to Ag2OAg2O and Ag metal, respectively, were seen in AgxOAgxO powder at each temperature; however, these Ag2O/AgAg2O/Ag ratios varied and the AgO form was not found in any of the samples. In the XPS data, the peak which was assigned to Ag3d5/2Ag3d5/2 in the Ag metal or Ag2OAg2O was present in all the AgxOAgxO samples. In particular, the peak of Ag3d5/2Ag3d5/2 in the Ag metal was dominant at high temperature, while the peak of Ag3d5/2Ag3d5/2 in Ag2OAg2O increased at low temperature. When TiO2TiO2 was used as a photocatalyst in the methanol photodecomposition reaction, no hydrogen gases were evolved. However, the hydrogen product was remarkably increased in the mixture of AgxOAgxO and TiO2TiO2 photo-system. Moreover, it was more enhanced when AgxOAgxO thermally treated at 100∘C was added, compared to the samples with AgxOAgxO thermally treated at other temperatures, and the production peaked at 17,000 μmol after 24 h.