NOVEL CARBON-ZrO2 COMPOSITES AS HIGHLY EFFICIENT VISIBLE-LIGHT PHOTOCATALYSTS

摘要

Semiconductor photocatalysis is an advanced technology that employs the electrons on the conduction band and holes on the valence band in photons excited semiconductor to remove pollutants via oxidization or reduction reactions. However, the photocatalytic efficiency in semiconductors is greatly affected by the quick recombination of charge carriers. The electron-hole pairs generated in the semiconductor by optical irradiation can be easily recombined and consequently, a loss of activity can be observed. Obviously, an ideal photocatalyst should be: (i) photoactive; (ii) biologically and chemically inert; (iii) active under visible and/or near-UV light; (iv) inexpensive and (v) photostable. TiO2 semiconductor satisfies the most of these criteria and so that is one of the most used photocatalysts [1]. However, only 3-5% of UV in solar spectrum can be absorbed by pure TiO2 due to the wide band gap (3.2 eV of anatase and 3.0 eV of rutile), which greatly restricts its photocatalytic applications in the visible-light range [2].