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Enhancing photocatalytic activity of disorder-engineered C/TiO₂ and TiO₂ nanoparticles

Wang, Shu, Zhao, Lei, Bai, Lina, Yan, Junmin, Jiang, Qing, Lian, Jianshe
Journal of materials chemistry A 2014 v.2 no.20 pp. 7439-7445
X-ray diffraction, absorption, air, carbon, energy, hydrogen, hydrogen production, light, nanocrystals, nanoparticles, oxygen, oxygen production, phenol, photocatalysis, photolysis, sol-gel processing, titanium dioxide, transmission electron microscopy
We demonstrate a simple and green synthetic pathway to prepare TiO₂–carbon nanoparticles (C/TiO₂ NPs) by the sol–gel method, abandoning additional carbon sources but utilizing the organic group in the Ti precursor. Then the C/TiO₂ NPs were decarburized under an air atmosphere at 500 °C for 2 h to form the reduced TiO₂ nanoparticles. XRD, Raman spectrum, HRTEM and electron energy loss spectrum (EELS) analyses showed that the C/TiO₂ NPs were composites of core-shell structured TiO₂ and amorphous carbon; and both C/TiO₂ and reduced TiO₂ NPs contained a large number of oxygen vacancies, which led to structural disorders in them. These structural disorders induced the valence band tails to enhance visible light absorption and to tailor the bandgap structures of the two modified TiO₂ samples to match the hydrogen and oxygen production energy levels. As a result, the two structure-disordered C/TiO₂ and reduced TiO₂ nanocrystals showed excellent solar-driven photocatalytic activities: the C/TiO₂ performed best on the photodegradation of phenol and methyl blue, while the reduced TiO₂ displayed an excellent hydrogen generation rate, 10 times higher than that of the reference TiO₂ by photo-splitting water.