Synthesis of Ag/AgCl-modified TiO2/MgAl-layered double hydroxide nanocomposite with enhanced photocatalytic activity

A novel composite photocatalyst Ag/AgCl-modified TiO2/MgAl-layered double hydroxide (denominated as Ag/AgCl@TiO2-LDH) was synthesized via a combination of deposition-precipitation process and photoreduction method by using layered double hydroxide (LDH) platelets as substrate materials. The structure, morphology, and property of as-synthesized Ag/AgCl@TiO2-LDH were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller method (BET), UV-vis diffuse reflectance spectroscopy, etc. The photocatalytic property of Ag/AgCl@TiO2-LDH was tested for degradation of gaseous toluene under simulated sunlight irradiation. The composite catalyst exhibited an enhanced photodegradation activity with 92% of gaseous toluene being degraded. Through kinetics analysis, all degradation processes of gaseous toluene could be properly described by the pseudo-first-order kinetic model. The reaction rate constant of 40 mg Ag/AgCl@TiO2-LDH for the degradation of 172.05 mg m(-3) gaseous toluene is 0.026 min(-1). Furthermore, the catalyst could be reused for five cycles without obvious reduction in activity. The enhanced photocatalytic activity of Ag/AgCl@TiO2-LDH is attributed to sufficient hydroxide ions in LDH, the Shottky barrier at the metal-semiconductor interface, and surface plasma resonance of Ag/AgCl. The cooperative effect among components separate photogenerated electrons and holes effectively and thus improve the photodegradation efficiency.