Cobalt Doping on Zirconium Titanate as a Potential Photocatalyst with Visible-Light-Response

Abstract

Synthesis of cobalt-doped zirconium titanate (Co-doped ZrTiO4) as a potential photocatalyst with visible-light-response had been conducted. Materials used in this research were titanium tetraisopropoxide (TTIP) as a precursor of TiO2, ZrO2 as another semiconductor for coupling, and CoSO4·7H2O as the source of cobalt dopant. The composite was prepared by the sol-gel method with various cobalt contents and calcination temperatures. Composites with various Co dopant contents (0, 1, 3, 5, 7, and 9% (Co wt./Ti wt.)) were calcined at 500 °C for 4 h. In addition, the composite with 5% of dopant content was calcined at 700 and 900 °C to observe the influence of calcination temperature. All samples were characterized by using X-ray powder diffraction method (XRD), Fourier-transform infrared spectroscopy (FTIR), specular reflectance UV-Vis spectroscopy (SRUV), and scanning electron microscopy equipped with X-ray energy dispersive spectroscopy (SEM-EDS). Co-doped ZrTiO4 with the lowest bandgap (2.94 eV) was achieved in a sample containing 3% of cobalt content calcined at 500 °C.

The Effects of Manganese Dopant Content and Calcination Temperature on Properties of Titania-Zirconia Composite

“…Furthermore, the higher calcination temperature was proven to enable the material transformations phase of anatase to rutile, which causes the E g value to be smaller. This result corresponds with other previous works in which the addition of dopant between 1-9% and calcination temperature would show optimum condition of doped composite [4,[6][7][8].…”

“…The addition of Mn dopant 1-7% was shown to be able to reduce the E g value, and it may possibly increase the response of the synthesized material under visible-light range. The E g values of Mn-doped TiO 2 -ZrO 2 increased as the addition of Mn dopant reached above 7% [4,6,21]. Furthermore, the higher calcination temperature was proven to enable the material transformations phase of anatase to rutile, which causes the E g value to be smaller.…”

“…Additionally, the composite with 5% of Mn content was calcined at 700 and 900 °C to observe the effect of calcination temperature. The variation of dopant percentage and calcination temperature were based on the previous works [6][7][8]. All samples were characterized by using XRD, FTIR, SR UV-Vis and SEM-EDX.…”

“…The metallic dopants with 3d orbitals, such as Mn, Fe, Co and Zn, had been studied and reported in recent years [5][6][7][8][9]. Transition metal will reduce the particle size of photocatalyst and increase its surface area, Table 1 shows the use of dopants with 3d orbitals on the photocatalyst materials that had been studied previously.…”

“…Doping photocatalyst with transition metals increases the surface defects and optical absorption of light, which can ultimately lead to an increase in the efficiency of the photocatalyst [9]. The lowest bandgap of TiO 2 -ZrO 2 doped using Fe (2.83 eV), Co (2.94 eV) and Zn (2.87 eV) were achieved in composites with 7% of iron content calcined at 500 °C, 3% of cobalt content calcined at 500 °C, and 5% of zinc content calcined at 900 °C, respectively [6][7][8]. The properties of semiconductor are enhanced after manganese doping because Mn 2+ and Mn 3+ exist on the surface of photocatalyst and catch the electron in semiconductor.…”