Interfacial optimization of oxygen-vacancy-induced 1D/2D CeO2 nanotubes/g-C3N4 step-scheme heterojunction with enhanced visible-light photocatalysis and mechanism insight

Abstract

Oxygen-vacancy-induced one-dimensional (1D) CeO2 nanotubes (CeNT) has successfully loaded on two-dimensional (2D) graphitic carbon nitride (g-C3N4) by simple methods for investigating the performance of photocatalytic degradation of sewage. The results of characterization analyses have proved that the CeNT are uniformly dispersed on the surface of the g-C3N4 nanosheets. The electron paramagnetic resonance (EPR) spectra signal exhibited the existence of oxygen vacancies in CeNT. Photoluminescence spectra (PL), UV–vis diffuse reflectance spectra (UV–vis DRS) and photoelectrochemical measurements demonstrated that the appropriate amount of CeNT (28 mg) can effectively improve the separation efficiency of photogenerated charge carriers and the photoresponse property of the samples. The rhodamine B (RhB) degradation experiments verify the same results that the photocatalytic degradation efficiency of the samples for RhB increased initially, followed by a decreased, meanwhile the degradation activity didn’t decrease prominently after four circles. Also, the reactive species trapping experiment indicated that the holes (h+) and superoxide radicals (∙O2-) played major role in the photocatalytic reaction. Finally, the enhanced photocatalytic performance can be attributed to the synergistic effects of the oxygen vacancies in CeNT and a new charge transfer mechanisms of Step-scheme heterojunction for electron separation, which could provide a new green solution for photocatalytic sewage treatment.