PtOx deposited Fe3O4-ZnO/TiO2 nanocomposites for photocatalytic H2 production under visible light

Abstract

In this work, TiO2 nanotubes, Fe3O4-ZnO, nanocomposites of Fe3O4-ZnO and TiO2 were synthesized by varying the amount (5, 10 and 15 wt%) of Fe3O4-ZnO. The obtained nanocomposites were decorated with PtOx (1.0 wt%) nanoparticles via green synthesis method using Chamomile flowers extract. The synthesized samples were thoroughly characterized by XRD, SEM, HRTEM, FT-IR, DRUV-vis, PL N2-physisorption and XPS spectroscopy measurements. The XRD, FT-IR, XPS spectroscopy and microscopy results revealed the existence of strong interaction between Fe3O4-ZnO and TiO2 nanotubes. Deposition of PtOx on the surface of TiO2, Fe3O4-ZnO and Fe3O4-ZnO/TiO2 nanocomposite samples resulted in a decrease in the bandgap to 3.26 eV, 1.90 eV and 1.80 eV respectively. Further, Fe3O4-ZnO/TiO2 nanocomposites exhibited relatively high surface area (95 m2g−1) and pore volume (0.174 cm3g−1) than Fe3O4-ZnO sample. The presence of surface PtOx species resulted in delaying the recombination of e-/h+ pairs. Different reaction conditions such as pH of solution, methanol/H2O ratio and catalyst mass were optimized to obtain high photocatalytic H2 production. The highest photocatalytic H2 production [485μmol/(gcatalysth)−1] was observed in case of Pt@Fe3O4-ZnO/TiO2-3 catalyst under visible light irradiation at 80 °C. In addition, the synthesized PtOx deposited nanocomposite materials could be separated easily from the reaction mixture and reused five times without considerable loss of photocatalytic activity.