Synthesis and Characterization of α-Fe2O3 based Nanocomposites for Photocatalytic Water Purification

Abstract

Environmental remediation via semiconductor heterogeneous photocatalysis is one of the outstanding and sustainable strategies to control the water pollution by series of redox reactions taking place at semiconductors surface. Tailoring photocatalytic materials to meet the increasing global energy demands and challenges related to decontamination of environment has been a very electrifying prospect for material chemists. Two major processes that limit the activity of any photocatalyst are the charge carrier recombination process as well as its UV light activity (as it comprises only 5% of solar spectrum). Hematite (α-Fe2O3), due to favorable visible light active band gap (i.e. 2.1 eV), has turned out to be hot material for diverse scientific applications related to energy generation, energy storage, sensors and environmental pollution alleviation etc. However, the photocatalytic efficiency of α-Fe2O3 is limited by the small life span of the light generated charge carriers (<10 ps). So our major concern is the engineering hematite photocatalyst with enhanced photodegradation of environmental pollutant. Herein, we report the synthesis of the novel α-Fe2O3 based Photocatalysts like α-Fe2O3/ ZnO, α-Fe2O3 /ZnTe and α- Fe2O3 /ZnSe via hydrothermal approach. X-ray Diffraction (XRD) spectroscopy was used to analyze the crystal structure, purity and phase of the heterostructured photocatalysts. Moreover, various crystalline parameters of synthesized photocatalysts were also calculated using XRD data. Morphological analysis was carried out via Scanning Electron Microscope (SEM). The elemental composition and purity of the synthesized photocatalysts was confirmed using EDX spectroscopy. The alignment of energy levels is an important parameter to determine the pathway of photocatalytic reactions and it was determined with the help of UV-Visible/DRS spectroscopy as well as XPS analysis. Finally, the as-synthesized heterostructures were used for the photocatalytic degradation of Congo red dye. The priority order of heterostructures according to photocatalytic activity is α-Fe2O3/ ZnO < α-Fe2O3 /ZnSe < α-Fe2O3 /ZnTe. α-Fe2O3/ZnTe showed maximum degradation efficiency up to 97%. The higher photocatalytic degradation efficiency was attributed to the synergistic effect and efficient charge carrier separation due to formation of Type-II configuration.