Self‐sacrificial Templated Synthesis of Fe/N Co‐doping TiO₂ for Enhanced CO₂ Photocatalytic Reduction

Abstract As a green photocatalyst, TiO₂ has been widely used in adsorption, desorption and redox reactions, but the wide energy band and moderate visible light absorption have greatly inhibited its applications in photocatalysis. The effective method of enhancing the performance of catalysts is the development of heterojunction and metal‐nonmetal co‐doping. Herein, Fe−N co‐doped TiO₂ heterojunction photocatalysts (Fe_xTi@C) were successfully synthesized by calcining a self‐sacrificial template (NH₂−MIL‐125(Ti)) injected with Fe³⁺ solution. X‐ray diffraction (XRD), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), N₂ adsorption/desorption analysis, and photoelectrochemical tests were used to characterize Fe_xTi@C, showing multiple rutile/anatase TiO₂ heterojunction structure, low bandgap, and significant absorption in visible light. In addition, the Ti−O−Fe tetrahedra and more oxygen vacancies were provided since the doped N is from the pristine MOF and the radii of Fe³⁺ and Ti⁴⁺ are similar, which improved the photocatalytic efficiency of CO₂ reduction to CH₄, especially the Fe_0.8Ti@C reached 7.8‐fold and 10.2‐fold CH₄ yield increase compared with the original TiMOF template and the undoped Ti@C, respectively. This work presents a simple method for the fabrication of low bandgap semiconductors, and also makes a new attempt at the synergistic effect between the in‐situ elements and valence bonds of MOF‐derived catalysts.