A novel double Z-scheme BiOBr-GO-polyaniline photocatalyst: Study on the excellent photocatalytic performance and photocatalytic mechanism

Abstract For Z-scheme photocatalytic systems, the presence of electron mediators and the establishment of multiple channels for carriers transfer are critical. Herein, a series of novel indirect double Z-scheme BiOBr-GO-polyaniline systems were rationally designed and successfully synthesized. Their physical and photochemical properties were characterized by means of scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photo-electron spectroscopy (XPS), UV–vis absorption spectra (UV–Vis DRS), transient photocurrent and electrochemical impedance spectroscopy (EIS). The results evidenced that the presence of GO and polyaniline obviously expanded the spectral response range and improved quantum yield. As expected, BiOBr-GO-polyaniline presented excellent photocatalytic activity and outstanding photostability in degradation of the colorless organic compound (phenol). Its highest degradation conversion of phenol was up to 89%, much higher than that of polyaniline (5%), BiOBr (34%), BiOBr-GO (43%) and BiOBr-polyaniline (55%). It is still active in the subsequent runs of photocatalytic degradation experiments of phenol, preserving 90% of the initial degradation conversion even after the fifth run. Moreover, based on experimental data analysis, sample characterization and band theory, the charge carriers migration process over BiOBr-GO-polyaniline system was proposed. In this system, the establishment of double Z-scheme ensured that high carrier separation and strong redox ability were simultaneously achieved.