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