Background: TiO2 photocatalyst is promising for wastewater treatment, but it is
still restricted under visible light.
Objective: To prepare TiO2 based-photocatalyst of good performance under visible light.
Methods: By doping manganese (Mn) and using multi-walled carbon nanotubes (MWCNTs)
as a substrate, we prepared carbon nanotube-supported Mn-TiO2 (Mn-TiO2/MWCNTs)
nano-composites with a solvothermal-annealing method. The samples were characterized by
means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning
electron microscopy (SEM). The photocatalytic activity of Mn-TiO2/MWCNTs was investigated
by the degradation of methylene blue (MB) under visible light.
Results: It was found that Mn-TiO2 nanoparticles were loaded uniformly on the MWCNTs.
Mn-TiO2/MWCNTs showed higher photocatalytic efficiency than pure TiO2 and Mn-TiO2.
Only 47.0% of MB was degraded by TiO2 and 67.2% of MB was degraded by Mn-TiO2,
while 80.0% of MB was degraded by Mn-TiO2/MWCNTs in 80 minutes.
Conclusion: Because the Mn doping reduced the energy gap of TiO2 and inhibited the recombination
of photogenerated electron-hole pairs and because the large suface area and
good electro-conductivity of MWCNTs enhanced the photocatalytic efficiency of TiO2, Mn-
TiO2/MWCNTs showed an enhanced catalytic performance under visible light.