Perovskite-type KTaO3–reduced graphene oxide hybrid with improved visible light photocatalytic activity

Abstract

Novel rGO–KTaO₃ composites with various graphene content were successfully synthesized using a facile solvothermal method which allowed both the reduction of graphene oxide and loading of KTaO₃ nanocubes on the graphene sheets. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) specific surface area, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) emission spectroscopy. The obtained rGO–KTaO₃ composites showed greatly improved photocatalytic performance for degradation of phenol under visible light irradiation (λ > 420 nm) over pristine KTaO₃ which could be related to the photosensitizer role of graphene in the rGO–KTaO₃ composites as well as the formation of p–n heterojunctions between KTaO₃ nanocubes and rGO sheets. The highest photocatalytic activity in phenol degradation reaction was observed for rGO–KTaO₃ hybrid with 30 wt% graphene. The enhanced photoactivity of this composite could be attributed to the synergistic effect of several factors such as: small crystallite size, extended absorption range in the visible spectrum and intimate contact between graphene and KTaO₃ cubes.