Development of Cu/TiO2 Photocatalyst for Hydrogen Production under Visible Light

Technologies for generating hydrogen from water using modified photocatalyst have drawn many attentions. In this study the photocatalysts for hydrogen generation were synthesized using two methods; complex-precipitation and wet impregnation method. Cu/TiO2 with 2, 5, 10 and 15 wt% loading was prepared, dried and prior to calcination, thermal gravimetric analysis was carried out to determine their thermal stability. Based on the thermograms, the calcination temperature was estimated to be 300°C or higher. Therefore, the photocatalysts were calcined at 300°C, 400°C and 500°C for 30 min. The effect of transition metal loading and calcination temperatures on the photocatalytic activity was investigated. Photocatalytic activity was carried out under visible light illumination (500 W halogen lamp as the light source). The screening process is used to monitor the photocatalytic activities for hydrogen production in a multiport reactor containing of photocatalyst, water and methanol (as scavenger). The amount of hydrogen produced decrease as the calcination temperature increases for all the catalysts. The photocatalysts were also characterized using Temperature Programmed Reduction (TPR), Diffuse Reflectance UV-Vis (DR-UV-Vis), Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform Infared (FTIR), X-ray Difractometer (XRD) and surface area determination (BET). The results from TPR and XRD indicated that the only Cu species present was CuO supported on TiO2. The SEM micrographs showed morphology of the prepared samples with particle size around 20 nm to 100 nm. The effect of transition metal loading was studied and found that incorporating with copper enhance the photocatalytic activity compared to TiO2. However higher concentration of transition metal loading up to 15 wt% led to the decrement of the photocatalytic activity. The lower photocatalytic activity can be influence by the surface saturation of Cu which minimized the light penetration from reaching to the surface of the TiO2. The incorporation of Cu transition metal had successfully shifted the TiO2 band gap to a longer wavelength as evidence by DR-UV-Vis.