Acid-treated g-C3N4-Cu2O composite catalyst with enhanced photocatalytic activity under visible-light irradiation

Acid-treated g-C 3 N 4 -Cu 2 O was prepared by hydrothermal reduction followed by high temperature calcination and acid exfoliation. The structures and properties of as-synthesized samples were characterized using a range of techniques, such as X-ray photoelectron spectroscopy, scanning electron microscopy, Photoluminescence Spectroscopy and the Brunauer–Emmett–Teller (BET) theory. The photocatalytic activity was evaluated by measuring the photodegradation of methyl orange under visible-light irradiation. Based on the results of TEM, XPS, EPR and other techniques, it was verified that a heterojunction was formed. The acid treatment process can increase the specific surface area to form abundant heterojunction interfaces as channels for photo-generated carrier separation, thereby enhancing its light utilization and quantum efficiency. Results indicate that acid-treated g-C 3 N 4 -Cu 2 O possesses a large specific surface area, which provides plentiful activated sites for heterojunctions to form; in addition, it showed a high visible light effect and the minimum charge-transfer resistance. Furthermore, the g-C 3 N 4 -Cu 2 O material exhibits high levels of effectiveness and stability. Electron paramagnetic resonance and a series of radical trapping experiments demonstrate that the holes and •O 2 − could be the main active species in methyl orange photodegradation. This work could provide new insights into the fabrication of composite materials as high-performance photocatalysts, and facilitate their application in addressing environmental protection issues.