Graphitic carbon nitride (g-C3N4) nanoparticles embedded in mesoporous TiO2 microspheres were prepared by direct incorporation of urea into the TiO2 microspheres, followed by annealing at 773 K in air. The resulting yellow microspheres (g-C3N4@TiO2) are about 450 nm in diameter, which were completely characterized by X-ray powder diffraction, elemental analysis, thermo gravimetric analysis, transmission electron microscope, scanning electron microscope, energy-dispersive X-ray spectrometry, UV-visible absorption spectroscopy, Brunauer-Emmett-Teller specific surface area, infrared spectroscopy, and X-ray photoelectron spectroscopy. The spectroscopic and analytical results clearly confirm that nanoparticles of g-C3N4 are incorporated into pores within the TiO2 microsphere. UV-visible absorption spectrum of g-C3N4@TiO2 show an absorption peak near at 555 nm, indicating g-C3N4@TiO2 can be photo-catalytically active by the visible-light alone. The ability to generate photocurrents of g-C3N4@TiO2 was examined using a standard photo electro chemical cell.  The chronoamperometry measurement was performed under an applied potential of 0.8 V (vs. Ag/AgCl) and using a periodic irradiation of visible-light (=420 nm). The current density of g-C3N4@TiO2 is 1.97 mA/cm2, which is higher than those of g-C3N4 (0.65 mA/cm2), mesoporous TiO2 microsphere(0.37 mA/cm2), and commercial TiO2 (P25, 0.13 mA/cm2). In addition, g-C3N4@TiO2 exhibits significantly improved visible-light driven activity toward degradation of methylene blue compared to its single-phase counterparts such as g-C3N4, mesoporous TiO2, and commercial TiO2. We will present the role of g-C3N4 in the mesoporous TiO2 microsphere and the surface effect on the photocatalytic activity in the g-C3N4@TiO2 nanocomposite.

Titania microspheres embedding nanoparticles of carbon nitride for improved visible-light photocatalytic activities

248th National Meeting (2014)

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