One-step in-situ synthesis of porous Fe3+-doped TiO2 octahedra toward visible-light photocatalytic conversion of CO2 into solar fuel

Abstract

Here, hollow Fe3+ doped TiO2 (Fe–TiO2) octahedra were obtained via one-step hydrothermal method with MIL-101(Fe) as the template as well as the iron ion source. By introducing Ti precursor onto MIL-101(Fe) followed by HF etching and hydrothermal treatment, Fe-doped TiO2 with high porosity and hollow structure was obtained. The as-synthesized Fe–TiO2 octahedra consist of numerous small nanoparticles with particle sizes between 10 and 20 nm and possess a high specific surface area of 275 m2 g−1 together with uniform mesopores of 3.7 nm in pore diameter. After heat treatment in air at 500 °C (named Fe–TiO2-500), the BET surface area and the mesopore size of the sample were changed to 202 m2 g−1 and 3.9 nm, respectively. Compared to other Fe-doping methods, this method reported here favors better and more uniform Fe doping into the TiO2 lattice and improves the porosity and specific surface area. As a result of the Fe doping, the bandgaps of Fe–TiO2 and Fe–TiO2-500 were about 2.75 eV and 2.42 eV, respectively. Fe–TiO2-500 shows excellent photocatalytic activity due to its special structure, high BET surface area and porosity. The yield of CH4 is about 7.73 μmol g−1 after loading of Pt within 12 h of reaction time under visible light illumination (λ > 420 nm).