Mesopores octahedron GCNOX/Cu2O@C inhibited photo-corrosion as an efficient visible-light catalyst derived from oxidized g-C3N4/HKUST-1 composite structure

Photo-corrosion of Cu2O photocatalyst considered as an important factor extremely restricts its catalytic activity. However, so far, there are few comprehensive reports on the mechanism of photo-corrosion inhibition and stability improvement of Cu2O in photocatalytic degradation. In this work, oxidized g-C3N4/Cu2O@C (GCNOX/Cu2O@C) visible-light catalysts with protective carbon layer were first prepared using the copper-based metal-organic frameworks (HKUST-1) composite as precursors. The UV-visible DRS, PL, XPS valence-band and Mott-Schottky curves were used to characterize that the formation of carbon layer leads to establishing built-in electric field, shifting of energy bands and photogenerated carrier separation. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) revealed that GCNOX/Cu2O@C had the strongest photo-response current and the lowest interface contact resistance. The photodegradation activity of GCNOX/Cu2O@C was analyzed for Rhodamine B (RhB) and ciprofloxacin (CIP) under low energy visible light irradiation and the degradation kinetic constants were 0.01413 min(-1) and 0.03958 min(-1), respectively, which were much higher than other as-prepared catalysts. It also exhibited outstanding stability with the 87.4% degradation efficiency in 90 min after four recycles. Furthermore, the characterization of GCNOX/Cu2O@C after the cyclic reactions further proved the ultra-high stability of the carbonized materials. Additionally, on the basis of degradation experiments and photoelectrochemical results, the possible transfer path of photocarriers between material interfaces, photo-corrosion inhibition mechanism of cuprous oxide and the transformation mechanism of active radicals were proposed. This work provided a novel insight for MOFs-derived composites as a highly efficient and stable visible-light catalyst.