DOI: https://doi.org/10.55373/mjchem.v25i3.192

Keywords: Titanium dioxide (TiO2); chromium; Cr-doped TiO2; sol-gel; anatase

Abstract

Titanium dioxide (TiO2) as photocatalyst has gained much attention for environmental treatments due to its attractive characteristics. The applications of TiO2 are significantly limited by its low visible light absorption, which is due to its large band gap. Doping TiO2 with transition metal is one of the promising approaches to improve its photocatalytic efficiency by expanding its ultraviolet (UV) absorption to visible region. In this work, chromium (Cr)-doped TiO2 nanoparticles (NPs) were prepared using sol–gel method at different calcination temperatures (400, 500, 600, and 700 °C). The structural properties for all samples were characterised using X-ray diffraction (XRD) and Fourier transform infrared (FTIR). XRD results show anatase phase observed in samples of pure TiO2 and Cr-doped TiO2 calcined at 400 °C. The rutile phase started to appear in sample of Cr-doped TiO2 calcined at 500 °C to form mixed anatase–rutile phase. The minimum size of anatase was 17.38 nm at calcination temperatures of 400 and 500 °C, whereas rutile size was 22.22 nm at 500 °C. The largest specific surface area (SSA) of anatase was 88.04 m2∙g−1 at 400 °C and 500 °C, while for rutile was 64.43 m2∙g−1 at 500 °C. FTIR analysis shows the bonding changes that occurred with the introduction of Cr into TiO2 nanoparticles.