A comprehensive comparison between BiFeO3-reduced graphene oxide (rGO) nanocomposite and Bi25FeO40-rGO nanocomposite has been performed to investigate their photocatalytic abilities in degradation of Rhodamine B dye and generation of hydrogen by water-splitting. The hydrothermal technique adapted for synthesis of the nanocomposites provides a versatile temperature-controlled phase selection between perovskite BiFeO3 and sillenite Bi25FeO40. Both perovskite and sillenite structured nanocomposites are stable and exhibit considerably higher photocatalytic ability over pure BiFeO3 nanoparticles and commercially available Degussa P25 titania. Notably, Bi25FeO40-rGO nanocomposite has demonstrated superior photocatalytic ability and stability under visible light irradiation than that of BiFeO3-rGO nanocomposite. The possible mechanism behind the superior photocatalytic performance of Bi25FeO40-rGO nanocomposite has been critically discussed.

No abstract

No abstract

DyFe0.1Cr0.9O3 nanoparticles calcined at 700 °C demonstrate superior photocatalytic ability compared to that of DyCrO3 nanoparticles calcined at the same temperature.

Hot electron emission from waveguide integrated graphene has been recently shown to occur at optical power densities multiple orders of magnitude lower than metal tips excited by subworkfunction photons. However, the experimentally observed electron emission currents were small, limiting the practical uses of such a mechanism. Here, we explore the performance limits of hot electron emission in graphene through experimentally calibrated simulations. Two regimes of non-equilibrium emission in graphene are identified, (i) single particle hot electron emission, where an electron is excited by a photon, and is emitted before losing significant energy through scattering, and (ii) ensemble hot electron emission, where the photon source causes nonequilibrium heating of the electron population beyond the electron lattice temperature. It is shown that through appropriate selection of photon energy, optical power density, and applied electric field hot electron emission can be used to create ultra-high current electron emitters with ultra-fast temporal responses in both the single particle and ensemble heating regimes. These results suggest that through appropriate design, hot electron emitters may overcome the limitations of thermionic and field emitters.