Design and synthesis of TiO2/ZnO nanocomposite with enhanced oxygen vacancy: Better photocatalytic removal of MB dye under visible light-driven condition

Abstract

• TiO 2 /ZnO nanocomposite was synthesized by a facile hydrothermal route. • C. verum leaf extract was utilized as a bio-reducing and templating agent. • TiO 2 /ZnO (0.5mol) exhibited superior photocatalytic activity against MB dye removal. • TiO 2 /ZnO increases surface oxygen vacancy supressing recombination of e - -h + pair. • Excellent catalytic performance is owing to controlled surface oxygen vacancy and small particle size. Construction of capable, affordable, transition metal-based catalysts featuring photocatalytic behaviour is urgently required and important. Herein, for the first time we have synthesized an eco-friendly, capsule shaped ZnO nanoparticles (NPs) anchored upon TiO 2 nanoplates, by utilizing bio-active components available in Cinnamon verum leaf extract. The bio-active components, linalool and phytol served as a self-reducing and gapping agent that enrich the surface with oxygen vacancy without disrupting lattice arrangement. The XRD results confirms presence of wurtzite ZnO, anatase and rutile TiO 2 NPs. Anatase TiO 2 with ZnO supress the electron-hole pair recombination effect. The delayed luminescence behaviour is consistent with the UV-DRS results and suggests that the band gap of TiO 2 /ZnO has been widened. SEM with EDX results justifies that TiO 2 /ZnO nanocomposite mounted oxygen vacancy in a controlled phenomenon, which can boost the separation efficacy of photogenerated carriers and is in good agreement with the PL results. Under visible light irradiation for 60 minutes, TiO 2 /ZnO significantly improves photocatalytic degradation for aqueous organic dye pollutants. The k value of the TiO 2 /ZnO (0.5 mol) nanocomposite is 2.5x10 -2 mint -1 which is comparably higher. The unusual nanoarchitecture, high surface area, and wide band gap of TiO 2 /ZnO are primarily responsible for its noticeably improved photodegradation performance.