Preparation, characterization and photocatalytic studies of K₂Al₂Ti₆O₁₆, K_2−xAg_xAl₂Ti₆O₁₆and K₂Al₂Ti₆O_16−xNy

Potassium hollandites, a class of framework titanates having square/rhombus shaped tunnels, have been investigated for photocatalytic degradation of methylene blue under visible light irradiation. K2Al2Ti6O16 was prepared by sol–gel method using ethylene glycol as gelating reagent. Silver and nitrogen doped K2Al2Ti6O16 were prepared by ion exchange and solid state methods, respectively. All these materials were characterized by powder XRD, FT-IR, SEM-EDS, photoluminescence (PL) and UV–vis DRS spectral measurements. Silver and nitrogen doped K2Al2Ti6O16 showed higher photocatalytic activity compared to parent K2Al2Ti6O16 in the degradation of methylene blue dye under visible light irradiation. The reasons for their higher photoactivity are given based on the results of PL spectral measurements. Different scavenger tests were carried out to detect the reactive species responsible for the degradation of methylene blue dye.