Photocatalytic Performance and Degradation Pathway of Rhodamine B with TS-1/C₃N₄ Composite under Visible Light

TS-1/C₃N₄ composites were prepared by calcining the precursors with cooling crystallization method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV-Vis diffuse reflection spectrum (DRS) and nitrogen adsorption-desorption isotherm. The photocatalytic performance of TS-1/C₃N₄ composites was investigated to degrade Rhodamine B (RhB) under visible light irradiation. The results showed that all composites exhibited better photocatalytic performance than pristine TS-1 and C₃N₄; TS-1/C₃N₄-B composite (the measured mass ratio of TS-1 to C₃N₄ is 1:4) had best performance, with a rate constant of 0.04166 min^-1, which is about two and ten times higher than those of C₃N₄ and TS-1, respectively. We attributed the enhanced photocatalytic performance of TC-B to the optimized heterostructure formed by TS-1 and C₃N₄ with proper proportion. From the results of photoluminescence spectra (PL) and the enhanced photocurrent, it is concluded that photogenerated electrons and holes were separated more effectively in TS-1/C₃N₄ composites. The contribution of the three main active species for photocatalytic degradation followed a decreasing order of ·O₂^-, ·OH and h⁺. The degradation products of RhB were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the possible photocatalytic degradation pathways were proposed.