Preparation and photoelectrochemical performance of potassium hexatitanate nanofilm

Nanostructured K₂Ti₆O₁₃ film photoelectrode produced in situ was prepared on indium-tin oxide (ITO) glass substrate by a sol-gel process and characterized by thermogravimetry (TG) and differential scanning calorimetry (DSC), X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Visible diffuse reflectance and Raman spectrometry. The photoelectrochemical performance of K₂Ti₆O₁₃ film was assessed by electrochemical method. The analytical results showed that the K₂Ti₆O₁₃ film had a strong and wide absorption in the ultraviolet and visible light range. The band gap energy (E_g) of the film shifted from 3.45 eV (bulk) to 3.05 eV (film). The flat-band potential (E_fb) of K₂Ti₆O₁₃ film was -0.67 V [vs.saturated calomel electrode (SCE)]. The transport of photogenerated electrons and holes was better in K₂Ti₆O₁₃ film electrode than that in TiO₂ film electrode. The photoelectrochemical response of K₂Ti₆O₁₃ photoelectrode was increased in electrolyte solution with KOH, compared with that in the solution without KOH. The adsorption of OH^- on the nanofilm acted as the surface activity center. The mechanism of photolysis was analyzed in terms of photoelectrochemical behavior.