AgBr/BiOI/g-C3N4 Photocatalyst with Enhanced Photocatalytic Activity under Visible-Light Irradiation via the Formation of Double Z-Type Heterojunction with the Synergistic Effect of Metal Ag

The AgBr/BiOI/g-C3N4 ternary photocatalyst based on BiOI/g-C3N4 binary material was successfully prepared by a mild and simple method. The structure and morphology of the ternary materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), and Fourier transform infrared spectroscopy (FT-IR). The better optical properties of AgBr/BiOI/g-C3N4 were proved via ultraviolet- visible diffuse reflectance spectroscopy (DRS) and photoluminescence emission spectroscopy (PL), and the possible improved photocatalysis methods for degrading methyl orange (MO) were studied accordingly. MO (20 mg/L) was degraded by visible-light photocatalysis, and the optimum composite ratio of AgBr was 20%. At the optimum compounding ratio, the photocatalytic degradation rate of MO to the catalyst reached 93.41% at 120 min, which was attributed to the double Z-type heterojunction between AgBr, BiOI, and g-C3N4 and the strong electron capture effect of elemental Ag. The stability of AgBr/BiOI/g-C3N4 was examined by four cycles of experiments. Eventually, via trapping experiments, it was discovered that the primary active factor was center dot O-2(-). Moreover, h(+) also played a certain role. Based on this result, the possible photocatalytic mechanism was presumed, which was a double Z-type heterojunction was formed among AgBr, BiOI, and g-C3N4, and the strong electron capture effect of elemental Ag also played an important role.

Automated summary

The AgBr/BiOI/g-C3N4 ternary photocatalyst based on BiOI/g-C3N4 binary material was successfully prepared by a mild and simple method. The structure and properties of the ternary materials were characterized, and it was found that the catalyst exhibited excellent optical properties and high efficiency in degrading methyl orange under visible light. The stability of the catalyst was also examined, and the primary active species involved in the photocatalytic process were identified through trapping experiments.