Sol-gel synthesized porous Yb-K₂Ti₆O₁₃(n) for photocatalytic degradation of azophloxine: effect of polyethylene glycol chain length

A sol-gel method was applied to prepare the porous ytterbium-doped potassium titanate. The materials were obtained by changing the chain length of polyethylene glycol (PEG) in the precursor. The PEG in the sol might be beneficial for the growth of K₂Ti₆O₁₃ crystals, but the PEG did not lead to any phase transformation. The pores in the Yb-K₂Ti₆O₁₃(n) samples became larger with a rising PEG chain length, and the particles also became larger. The largest BET surface area (26.79 m²/g) and pore volume (0.0465 cm³/g) were obtained for the Yb-K₂Ti₆O₁₃(2000). The largest number of hydroxyl radicals were generated by the Yb-K₂Ti₆O₁₃(2000) that had the strongest photocatalytic activity, and a total of 87.6% of azophloxine was degraded in 30 min of irradiation. The photocatalytic reaction caused the degradation of the organic groups in the dye. The degradation efficiency in the first cycle was determined to be 87.7% in the solution using the Yb-K₂Ti₆O₁₃(2000), and the degradation efficiency was 64.1% in the fifth cycle.