Novel photocatalyst: sulfur-doped graphitic carbon nitride

摘要

The search for highly efficient photocatalysts has been intensifying worldwide due to their promising applications in, for example, renewable energy and the oxidative degradation of aqueous and atmospheric pollutants. Scientists at the Australian Institute for Bioengineering and Nanotechnology, University of Queensland, together with their collaborators from Institute of Metal Research, Chinese Academy of Sciences, have recently developed novel photocatalysts with excellent photo-oxidation and photo-reduction capacity (Liu G., Niu P., Sun C.H., Smith S.C., Chen Z.G., Lu G.Q., Cheng H.M. J. Am. Chem. Soc., 2010, 132, 11642-8). Their strategy uses sulfur atoms to dope graphitic carbon nitride (C3N_(4-x)S_x). The photoreactivity of C3N_(4-x)S_x for H2 evolution from photoreduction of water is 7.2 and 8.0 times higher than that of pure C3N4 under irradiation with λ > 300 nm and λ > 400 nm, respectively. Moreover, C3N_(4-x)S_x completely oxidises phenol under irradiation with λ > 400 nm, which is impossible for C3N4, even for λ > 300 nm. Ab initio calculations revealed the preferred lattice substitution sites, where S replaces N, and clarified that homogeneous substitution of sulfur in this way, coupled with a concomitant quantum confinement effect, are the chief causes of this remarkable electronic and photoreactive functionality. These results collectively indicate new opportunities for designing advanced photocatalysts for clean energy production and water/air purification.