Sol–Gel Synthesis of Porous Na₂Ti₆O₁₃: Effects of Polyethylene Glycol on Photocatalytic Degradation of Ofloxacin

Abstract Polyethylene glycol (PEG) modified Na₂Ti₆O₁₃(m = gram of PEG in the precursor) samples are synthesized via a sol–gel method to determine the effects of PEG on the porosity and activity of Na₂Ti₆O₁₃. PEG prohibited the growth of Na₂Ti₆O₁₃ crystals in a rhombic system. The Na₂Ti₆O₁₃(m) samples prepared using PEG are quite porous without large and dense particles. PEG obviously increased the porosity in Na₂Ti₆O₁₃(m), while the specific surface area increased from 4.3 m² g⁻¹ (Na₂Ti₆O₁₃) to 15.7 m² g⁻¹ (Na₂Ti₆O₁₃(1.5)), and the pore volume increased from 0.0072 to 0.0265 cm³ g⁻¹ at the same time. The bandgap energies of Na₂Ti₆O₁₃, Na₂Ti₆O₁₃(0.5), Na₂Ti₆O₁₃(1.5) and Na₂Ti₆O₁₃(2.5) are 3.15, 3.31, 3.53, and 3.58 eV, respectively. The photoluminescence intensities of the Na₂Ti₆O₁₃(m) samples are in the reducing sequence: Na₂Ti₆O₁₃, Na₂Ti₆O₁₃(2.5), Na₂Ti₆O₁₃(0.5) and Na₂Ti₆O₁₃(1.5). The initial ofloxacin molecules in the solution are almost fully degraded after 70 min of irradiation using Na₂Ti₆O₁₃(1.5), while the degradation efficiency of Na₂Ti₆O₁₃ is only 61.0% at the same time.