As illustrated in Fig. 6a, the FT-IR spectra of the 3% MWNTs–Bi2WO6 composite and pure Bi2WO6 were similar to each other, which was reasonable since Bi2WO6 was predominant in the composite. After adsorption with TC, the spectrum of the composite changed. Several new peaks appeared in the region of 1000 ∼ 1400 cm−1 due to the adsorption of TC on the surface. By comparison with the FT-IR spectrum of TC (shown in Fig. S5), it GPLG0634 is clear that the new peaks corresponded to the stretching vibration of the bonds, which were labeled by dashed lines in Fig. S5, in TC molecules. The spectra of the composite after adsorption of TC and after degradation for 1 h were similar to each other, implying terminal buds adsorbed substance on the surface was still TC after irradiation for 1 h. However, after irradiation for 3 and 5 h, the spectra changed distinctly with the disappearance of the peaks at 1200 ∼ 1250 cm−1 and 1300 ∼ 1350 cm−1, which were assigned to CN amine stretching vibration and CH3 deformation vibration , respectively. The disappearance of these two peaks implies that the adsorbed TC was degraded and transformed to some intermediate products through losing the CH3, NH2 or N(CH3)2.