Visible light sensitive hexagonal boron nitride (hBN) decorated Fe2O3 photocatalyst for the degradation of methylene blue

Abstract

The role of the carbon-based two-dimensional (2D) structures such as graphene or graphene oxide on the properties of metal oxide/2D composites materials are extensively studied for the environmental applications like photocatalysis. However, the metal oxide/inorganic 2D structure-based composites are less explored. In this regard, we have explored the α-Fe2O3/inorganic 2D hexagonal boron nitride (hBN) composite as an efficient visible light photocatalyst for the degradation of methylene blue (MB). A systematic investigation on the role of varying the weight percent of hBN on the photocatalytic efficiency for MB degradation under visible light was studied. The α-Fe2O3/(x) hBN (x = 1, 5, 10 wt%) composites were characterized by various analytical and spectroscopic techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The bandgap tuning with varying compositions of α-Fe2O3/(x) hBN (x = 1, 5, 10 wt%) were investigated by UV–vis diffuse reflectance spectroscopy (UV DRS) and the bandgap values were found to decrease with addition of hBN (1.56 eV for 5 wt%) compared to bare α-Fe2O3 (2.02 eV). The composite α-Fe2O3 with 5 wt% of hBN (FB2) showed an enhanced methylene blue (MB) degradation of ~ 91% with a high rate constant value of 5.03 × 10–4 s−1. This was ~ 3.3 times higher than the rate constant observed for the MB degradation using bare hematite. The material after photocatalysis process was retrieved by simple sedimentation process and reused for four cycles with no loss in degradation efficiency. The as-prepared composite material may have application in recycling and reuse of water in textile industries.