α-Fe2O3 nanospheres: facile synthesis and highly efficient photo-degradation of organic dyes and surface activation by nano-Pt for enhanced methanol sensing

Abstract

We report a simplified electrochemical route to synthesize thin films of nanosphere α-Fe₂O₃ from a suitable electrolytic solution. X-ray diffraction studies revealed the formation of pure hematite phase (hexagonal structure) α-Fe₂O₃ films. Field emission scanning electron microscopy revealed a highly compact surface morphology with evenly distributed almost spherical grains. Raman, electron paramagnetic resonance and Fourier transform infrared spectroscopic analyses confirmed the presence of α phase Fe₂O₃ (hematite). Optical analysis revealed a band gap energy of 2.15 eV; this is most suitable for visible light driven photocatalysis towards the degradation of Indigo Carmine (IC) and Rhodamine B (Rh B) dyes, which are widely used in the textile industry and were taken as model organic compounds. About 90% photodegradation was achieved at rates of 0.0188 min⁻¹ for IC and 0.0133 min⁻¹ for Rh B. The synthesized films were used as modified electrodes, and their catalytic activity towards methanol oxidation was investigated. A comparison was also made between Pt modified FTO/Fe₂O₃ and unmodified FTO/Fe₂O₃ electrodes towards dye degradation and methanol oxidation, and it was found that the Pt modified FTO/Fe₂O₃ electrode yielded superior results.