Enhanced photocatalytic degradation of rhodamine B and malachite green employing BiFeO3/g-C3N4 nanocomposites: An efficient visible-light photocatalyst

Abstract

A simple sonication technique was used to synthesize the g-C3N4 nanoparticle decorated with BiFeO3. Various techniques, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscope (TEM), UV–Vis diffuse reflection spectroscopy (UV-DRS), and X-ray photoelectron spectroscopy (XPS) were used to analyze the structural and optical characteristics of BiFeO3/g-C3N4 composites. In comparison to pristine g-C3N4, the synthesized BiFeO3/g-C3N4 composite displays exceptional photocatalytic activity. The increased photocatalytic activity of the BiFeO3/g-C3N4 composite was assigned mostly to the separation of photogenerated electron-hole (e-&h+) pairs caused by charge migration. A potential photocatalytic process for dye degradation was proposed over a BiFeO3/g-C3N4 composite. The BiFeO3/g-C3N4 composite possessed the highest photodegradation of 96% for rhodamine B (RhB) and 86% for malachite green (MG) dye in a short time, like 40 min and 50 min, respectively, at pH 3 under visible light exposure. For different concentrations and doses, the photocatalytic degradation of RhB and MG followed a pseudo-first-order rate with K values of 0.079 min−1 and 0.039 min−1, respectively. Furthermore, BiFeO3/g-C3N4 demonstrated high photo-stability for organic dye degradation during five consecutive cycles with little effect on photocatalytic activity. As a consequence, the organic dyes were oxidized into non-toxic molecules like water (H2O) and carbon dioxide (CO2). Hydroxyl radicals (OH•) and superoxide radicals O2-∙ have been found as the reactive species in the photocatalytic process over BiFeO3/g-C3N4.