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

By using TiO 2 and Ta 2 O 5 colloids, a stable and efficient visible-light driven photocatalyst , Er 3+ :Y 3 Al 5 O 12 /TiO 2 Ta 2 O 5 /MoO 2 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 Er 3+ :Y 3 Al 5 O 12 nanoparticles were embedded in TiO 2 Ta 2 O 5 matrix. UV–vis absorption and PL spectra of Er 3+ :Y 3 Al 5 O 12 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 TiO 2 and Ta 2 O 5 on visible-light photocatalytic hydrogen generation activity of Er 3+ :Y 3 Al 5 O 12 /TiO 2 Ta 2 O 5 /MoO 2 composite membrane were studied in detail. The experimental results showed that the photocatalytic hydrogen generation activity of Er 3+ :Y 3 Al 5 O 12 /TiO 2 Ta 2 O 5 /MoO 2 composite membrane heat-treated at 550 °C for 3.0 h was highest when the molar ratio of TiO 2 and Ta 2 O 5 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 Er 3+ :Y 3 Al 5 O 12 /TiO 2 Ta 2 O 5 /MoO 2 membrane was proposed based on PL spectra.