Design, synthesis, and structural characterization of Fe2+-doped anatase TiO2 nanocrystals and its impact on electronic properties and photocatalytic activity

Abstract

Anatase-phase TiO₂ nanorods with diameters of approximately 3 ± 1 nm and lengths of 40 ± 10 nm were successfully synthesized using a solvothermal method, followed by metal doping through thermal diffusion of Fe²⁺ ions onto the nanocrystals. The dopant incorporation process led to a significant enhancement in the visible light absorption of TiO₂, as observed from the red-shift in the UV-visible absorption spectra. This modification suggests a narrowing of the bandgap, making the material more suitable for photocatalytic applications under visible light. Specifically, Fe-doped TiO₂ nanorods with 1.0% Fe²⁺ exhibited a 35% increase in photocatalytic hydrogen production under visible light illumination compared to pure TiO₂. Electron microscopy and X-ray diffraction (XRD) analysis confirmed that the size and morphology of the nanocrystals remained unaffected by the doping process, retaining their anatase phase with no significant structural alteration. Additionally, UV-visible spectroscopy demonstrated a reduction in the bandgap energy of the TiO₂ nanorods from 3.5 eV in pure TiO₂ to a range of 3.14–3.34 eV for the Fe-doped samples. This decrease in bandgap energy is attributed to the introduction of iron ions into the TiO₂ lattice, which facilitates enhanced light absorption and improved photocatalytic efficiency. The ability to precisely control the dopant concentration while preserving the structural integrity of the TiO₂ nanocrystals is a key advantage of this method. The findings suggest that Fe-doped TiO₂ nanorods, with their enhanced photocatalytic activity, could serve as efficient materials for various applications, including hydrogen production, solar cells, and environmental sensing. These findings highlight the potential of Fe-doped TiO₂ nanorods as efficient materials for a range of clean energy technologies and environmental remediation processes.