The surface diffuse reflection spectra of the as-prepared mem-branes and pure TiO2 nanofibers are presented in Fig. 3a. The reflection in the region of visible lights (400–800 nm) is decreased by 10% for CNTs/TiO2 nanofiber membrane relative to the pure TiO2 nanofiber membrane with the same thickness. The enhanced optical absorption is contributed by the carbon component in the mem-brane, which may improve the ability of photodegrading MB [13]. Fig. 3b displays the photodegradation behaviors of MB catalyzed by pure TiO2 nanofibers and the CNTs/TiO2 membrane. Under UV irradiation for 100 min, the MB molecules were almost decomposed by the CNTs/TiO2 membrane, while about 40% of the MB molecules still remained in the solution in the case of TiO2 nanofibers. Furthermore, real solar light can photodegrade MB with this composite membrane (Fig. S2, see Supplementary materials). Evi-dently, CNTs/TiO2 membrane exhibited higher photocatalytic activ-ity than that of pure TiO2 nanofibers. The enhanced performance is attributed to the coupling of CNTs, which serve as the electron acceptors and improve the separation of photo generated charges and light harvesting [11], leading to an enhancement of the light quantum yield and photocatalytic performance.