Decolorization of Rhodamine B in a thin-film photoelectrocatalytic (PEC) reactor with slant-placed TiO2 nanotubes electrode

TiO2 slant-placed thin-film photoelectrocatalytic (PEC) reactor has been proved to be an efficient reactor to treat dye wastewater. However the different surface morphology of the TiO2 will influence the treatment efficiency of the reactor. In this work, a TiO2 nanotubes electrode was prepared by anodization method. It was used in a conventional photocatalytic (PC) reactor and slant-placed thin-film PEC reactor to treat Rhodamine B (RhB) solution and compared with TiO2 electrode prepared by sol–gel method, which was planar on surface. The results showed that the TiO2 nanotubes performed obviously better in conventional PC reactor, 30% better than the sol–gel electrode to treat 20 mg L−1 RhB in 180 min, consistent with the higher photo-current response. However in the thin-film PEC reactor, TiO2/Ti electrodes prepared by the two methods performed very similarly, 97% and 98% of 20 mg L−1 RhB were degraded respectively in 1 h in the optimal conditions. Even photocatalysis (PC) by the sol–gel electrode was higher than by the anodized electrode. The results also indicated that the enhancement of mass transfer in the thin-film PEC reactor is more beneficial for the sol–gel electrode in the degradation of RhB.

► TiO2 nanotubes electrode is prepared by anodization and applied to degrade RhB.
► Nanotubes electrode performs better than sol–gel electrode in conventional reactor.
► Nanotubes and sol–gel electrodes perform similarly in slant-placed thin film reactor.
► The blind pore architecture decreases the efficient surface area of TiO2 nanotubes.
► Thin-film reactor makes up the shortage of less surface area of sol–gel electrode.