Sol-gel synthesis of Er3+:Y3Al5O12/TiO2Ta2O5/MoO2 composite membrane for visible-light driving photocatalytic hydrogen generation

By using TiO2 and Ta2O5 colloids, a stable and efficient visible-light driven photocatalyst, Er3+:Y3Al5O12/TiO2Ta2O5/MoO2 composite membrane, was successfully prepared via sol-gel dip coating method at room temperature. The XRD, FTIR, SEM, TEM and EDX results confirm that approximately spherical Er3+:Y3Al5O12 nanoparticles were embedded in TiO2Ta2O5 matrix. UV-vis absorption and PL spectra of Er3+:Y3Al5O12 were also determined to confirm the visible absorption and ultraviolet emission. The photocatalytic hydrogen generation was carried out by using methanol as sacrificial reagent in aqueous solution under visible-light irradiation. Furthermore, some main influence factors such as heat-treated temperature, heat-treated time and molar ratio of TiO2 and Ta2O5 on visible-light photocatalytic hydrogen generation activity of Er3+:Y3Al5O12/TiO2Ta2O5/MoO2 composite membrane were studied in detail. The experimental results showed that the photocatalytic hydrogen generation activity of Er3+:Y3Al5O12/TiO2Ta2O5/MoO2 composite membrane heat-treated at 550 °C for 3.0 h was highest when the molar ratio of TiO2 and Ta2O5 was adopted as 1.00:0.50. And that a high level photocatalytic activity can be still maintained after four cycles. In addition, a possible mechanism for the visible-light photocatalytic hydrogen generation of the Er3+:Y3Al5O12/TiO2Ta2O5/MoO2 membrane was proposed based on PL spectra.