Pulsed-spray evaporation CVD synthesis of hematite thin films for catalytic conversion of CO

Catalytically active thin films of hematite (α-Fe2O3) were synthesized by pulsed-spray evaporation chemical vapor deposition (PSE-CVD) with Fe(acac)3 as the precursor. The obtained films were comprehensively characterized with X-ray diffraction (XRD), emission Fourier transform infrared (FTIR) and Raman spectroscopy, Scanning electron microscopy (SEM), Helium ion microscopy (HIM), Energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and Ultraviolet–Visible (UV–Vis) spectrometry. The catalytic behavior of the prepared α-Fe2O3 thin film towards total oxidation of CO was investigated in a plug-flow reactor. The structural analysis revealed that only the single-phase inverse spinel type α-Fe2O3 was obtained at the deposition temperature of 300 °C. The optical band gap energy was estimated to be 2.16 ± 0.05 eV. The results showed that α-Fe2O3 can initiate CO oxidation at 230 °C, enabling the production of CO2 at much lower temperature compared to the reaction performed without catalyst. It also demonstrated that the hematite thin films prepared here can be competitive to catalysts described in the literature. Both the lattice and adsorbed oxygen detected by XPS were proposed to be consistent with the Eley–Rideal mechanism for CO conversion.