Carbon-modified BiVO4 microtubes embedded with Ag nanoparticles have high photocatalytic activity under visible light

Carbon-modified BiVO(4) microtubes embedded with Ag nanoparticles (BVO@C/Ag MTs) were obtained by a two-step fabrication route. First, the BiVO(4)@carbon core-shell microtubes (BVO@C MTs) were fabricated by using BiVO(4) microtubes (BiVO(4) MTs) as a hard-template through a hydrothermal approach. Next, small Ag nanoparticles (Ag NPs) with well-dispersed distribution were assembled inside the carbon layer of the BVO@C MTs via an in situ reduction method. The results showed that small Ag NPs were well dispersed inside the carbon layer of approximately 8 nm in thickness around the BiVO(4) microtubes. The photocatalytic studies revealed that the BVO@C/Ag MTs exhibited the highest photocatalytic activity for photodegradation of rhodamine B (RB) compared to the pure BVO-MTs, BVO@C MTs under visible light irradiation. The high separation efficiency of photogenerated electron-hole pairs based on the photosynergistic effect among the three components of BiVO(4), carbon, and Ag and the improved visible light utilization from the sensitizing effects of carbon layers both contribute to the enhanced photocatalytic activity. The BVO@C/Ag MTs did not exhibit any significant loss of activity after three cycles of RB photodegradation, which results from the fact that the presence of the carbon layer could inhibit loss and oxidation of Ag NPs during repeated applications. The BVO@C/Ag MTs could be easily recovered by sedimentation due to their one-dimensional nanostructural property.