Effect of SnO2 incorporation on the photoelectrochemical properties of α-Fe2O3–SnO2 nanocomposites prepared by hydrothermal method

Abstract

In this work, we report the effect of tin oxide (SnO2) incorporation on the photoelectrochemical (PEC) water oxidation activity of hematite-tin oxide (α-Fe2O3–SnO2) nanocomposites prepared by hydrothermal method. During synthesis of α-Fe2O3–SnO2, the proportions of SnO2 in the composites were varied from 5 wt% to 50 wt%. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. XRD results showed diffraction signals from both α-Fe2O3 and SnO2 in the composite structure. The surface morphology and size features of α-Fe2O3 altered drastically with addition of SnO2. TEM analysis revealed that small-sized SnO2 were coated on the surface of α-Fe2O3, forming heterogeneous grain boundary interfaces. The α-Fe2O3–SnO2 nanocomposites were tested as photoanode for PEC water oxidation under standard 1 Sun illumination condition in 1 M NaOH. Among the various compositions, α-Fe2O3–SnO2 (50 wt%) displayed promising water splitting photocurrent density of 0.32 mAcm−2 at 1.4 V versus RHE, which is a 5-fold higher as compared to the photocurrent density of pure α-Fe2O3 (0.06 mAcm−2). This enhancement in photocurrent density can be attributed to the reduced electron-hole recombination as a result of better charge separation at local heterojunction between α-Fe2O3 and SnO2 in the composite.