Enhanced catalytic performance of β-FeOOH by coupling with single-walled carbon nanotubes in a visible-light-Fenton-like process

Carbon nanotubes/akaganeite composite photocatalysts (CNTs/beta-FeOOH) with different weight addition ratios of CNTs have been synthesized by a very simple hydrothermal method. X-ray diffraction, Fourier transform infrared spectrum, UV-vis diffuse reflectance spectra, scanning electron microscopy, and transmission electron microscope were used to characterize the composite photocatalysts. This study investigates the oxidative degradation of methyl orange, a probe contaminant, by a heterogeneous photo-Fenton-like process over the prepared composite photocatalysts. The CNTs/beta-FeOOH composites exhibit remarkably enhanced photocatalytic activity toward the degradation of methyl orange in water under visible light irradiation as compared with bare beta-FeOOH. The added CNTs have triple crucial roles in the promotion of photocatalytic activity of beta-FeOOH. One is to trap electrons and effectively hinder recombination of the photoexcited carriers. Two is to act as a dispersing support to control the particle size of beta-FeOOH in the CNTs/beta-FeOOH composites. Three is to enhance the visible light absorption intensity. Finally, the catalytic mechanism of CNTs/beta-FeOOH composite is proposed.