Microbial synthesis of Cu7S4/rGO nanocomposites with efficient photocatalytic activity for the degradation of methyl green

Abstract

Cu₇S₄/reduced graphene oxide (rGO) photocatalysts are attracting increasing interest because of their low cost and environmental friendliness. In this study, Cu₇S₄/rGO nanocomposites with high visible-light photocatalytic activity were successfully synthesized via biological and chemical methods. The prepared Cu₇S₄/rGO nanocomposites exhibited exceptional photocatalytic activity for methyl green (MG) reduction. In particular, the nanocomposites photocatalyst with A-N (biosynthesis with Na₂S as the sulfur source) provided the best photocatalytic performance, and could degrade 98.3% MG within 100 min. Their photocatalytic activity sequence is in the following order: A-N (98.3%) > A-U (biosynthesis with CuSO₄ as the copper source) (97.8%) > A-C (biosynthesis with CH₄N₂S as the sulfur source) (97.7%) > A-180 (96.7%) (chemical synthesis at 180 °C in a steel autoclave) > Cu₇S₄ (69.8%). After five repeated tests, the photocatalyst used in this study showed excellent stability. The photocatalytic activity enhancement can be attributed to Cu₇S₄ combined with rGO, which can enhance the active center and increase electron transfer. This study provides a novel method for the preparation of a photocatalyst that can quickly and effectively solve dye pollution, and reduce other pollutants. Additionally, the photocatalyst is expected to be used in the fields of photocatalysis, water decomposition and solar cells.