Synthesis and characterization of enhanced visible light-driven C-doped ZnO-2D GO/g-C3N4 heterojunction photocatalyst

Abstract

Well-designed 2D graphene oxide-modified polymeric graphitic carbon nitride composite nanosheets (GO/g-C3N4) as desirable sensitizers and catalytic substrates for optimising the visible light-driven photocatalytic performance of ZnO-based photocatalysts have been investigated. Herein, 2D GO/g-C3N4 composite nanosheets are first developed by ultrasonic and hydrothermal methods, and then coupled with ZnO nanoparticles to prepare a series of ternary GO/g-C3N4-ZnO heterojunction composites with vary GO loading concentrations. Characterization of the photocatalysts was carried out by SEM, TEM, XPS, XRD, DRS, photoluminescence (PL) spectroscopy; evaluation of the visible light photocatalytic activity was performed by degrading an aqueous methylene blue (MB) solution. XPS studies showed that the formation of a ZnC bond in 15 % GO/g-C3N4-ZnO is due to the replacement of oxygen by carbon, indicating the construction of a hybrid heterojunction composed of C-doped ZnO and visible light sensitive GO/g-C3N4 composite nanosheets. The photodegradation performance of 15 % GO/g-C3N4-ZnO is 5.3, 2.9, and 2.2 times higher than that of pure ZnO, g-C3N4, and g-C3N4-ZnO, respectively. Due to the increase of GO loading in GO/g-C3N4 composite nanosheets, some characteristics of efficient visible light photocatalysis, such as a wider light absorption range, fluorescence quenching in the PL spectrum, excellent optical response in photocurrent measurement, and good stability，were confirmed and can be attributed to the electronic interaction between heterostructures and the effective transfer of photogenerated electrons in these ternary nanocomposites. This work may provide a new promising pathway for the construction of easily prepared 2D GO/g-C3N4 hybrid-modified nanocomposites, which is a hopeful material for wastewater control.