Efficient organic contaminant degradation by visible-light-driven Z-scheme g-C3N4/Bi2S3 heterojunction under the experimental and natural environment

Abstract

In this study, a series of Z-scheme g-C3N4/Bi2S3-X (CN/Bi2S3-X) photocatalysts with different ratios were prepared by a simple hydrothermal method for degradation of MB. The decomposition rate of MB reached 96.12 % over CN/Bi2S3–20 % under 60 min of visible light irradiation, which was 2.05 and 2.02 times higher than that of pure Bi2S3 and g-C3N4, respectively. In addition, CN/Bi2S3–20 % can effectively degrade MB over a wide pH range (3–11) and a low catalyst dosage (10 mg). And CN/Bi2S3–20 % demonstrated a high degradation efficiency of MB in various real water bodies, including rainwater, ultrapure water, tap water, lake water, and industrial wastewater, with a rate of up to 90 %. Furthermore, CN/Bi2S3–20 % has a certain universality and a practical application prospect, which effectively degraded various contaminants, such as RhB (57.8 %), TC (56.7 %), NOR (62.1 %) and MG (70.8 %). The analysis of active species, EPR and well-matched band positions showed that the electron transfer mechanism is consistent with the Z-scheme heterojunction, which could well retain the strong redox ability. Moreover, a possible degradation pathway for MB was deduced according to the HPLC-MS results. This study provides a handy approach to constructing g-C3N4-based Z-scheme photocatalysts for the efficient degradation of pollutants.