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Abstract
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The titanium dioxide/ZnAl-layered double hydroxide (TiO2/ZnAl-LDH) nanocomposite was first prepared using
the co-precipitation method, and the TiO2/metal mixed oxide (TiO2/MMO) was then fabricated by annealing
the TiO2/ZnAl-LDH nanocomposite at 430 °C. The obtainedmaterials were characterized bymeans of techniques,
such as field emission scanning electronmicroscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared
spectroscopy (FT-IR), UV–visible diffuse reflectance spectroscopy (DRS), and N2 adsorption-desorption
(BET). Photocatalytic activities of the TiO2/MMO nanocomposite was evaluated for O2 generation from aqueous
solutions in the presence of AgNO3 (1 mmol) as the sacrificial agent at neutral pH and room temperature under
visible-light irradiation. It is found that photocatalytic activity of the TiO2/MMO sample was better than that of
the TiO2/ZnAl-LDH sample, which could be attributed to the reduction in bandgap energy, low electron-hole recombination,
and high surface area. An O2 generation rate of 371 μmol/(g h)was achieved over 20mg of the TiO2/
MMO nanocomposite photocatalyst, and the quantum efficiency for O2 generation was 84% at 400 nm. Such a
quantum efficiency was the highest value obtained over the TiO2/MMO sample under visible-light illumination.
This study presents a novel approach forwater oxidation using the visible-light-responsive TiO2/MMO nanocomposite
photocatalyst, which might be applied as a promising candidate in solar energy conversion and environmental
science for highly efficient O2 generation.
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