18 research outputs found
Crystal structure of polymeric carbon nitride and the determination of its process-temperature-induced modifications
Based on the arrangement of two-dimensional 'melon', we construct a unit cell
for polymeric carbon nitride (PCN) synthesized via thermal polycondensation,
whose theoretical diffraction powder pattern includes all major features
measured in x-ray diffraction. With the help of this unit cell, we describe
the process-temperature-induced crystallographic changes in PCN that occur
within a temperature interval between 510 and 610 °C. We also discuss further
potential modifications of the unit cell for PCN. It is found that both
triazine- and heptazine-based g-C3N4 can only account for minor phases within
the investigated synthesis products
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Photophysics of polymeric carbon nitride: An optical quasimonomer
A comprehensive investigation of the luminescent properties of carbon nitride polymers, based on tri-s-triazine units, has been conducted. Steady-state temperature- and excitation-power-dependent as well as time-resolved measurements with near-UV excitation (λ=325 nm and 405 nm) yield strong photoluminescence, covering the visible spectrum. The spectral, thermal, and temporal features of the photoluminescence can be satisfactorily described by the excitation and radiative recombination of molecular excitons, localized at single tri-s-triazine units. The discussed model is in accordance with the recently reported absorption features of carbon nitride polymers. Thus, from the point of view of optical spectroscopy, the material effectively behaves as a monomer
An optical quasimonomer
A comprehensive investigation of the luminescent properties of carbon nitride
polymers, based on tri-s-triazine units, has been conducted. Steady-state
temperature- and excitation-power-dependent as well as time-resolved
measurements with near-UV excitation (λ=325 nm and 405 nm) yield strong
photoluminescence, covering the visible spectrum. The spectral, thermal, and
temporal features of the photoluminescence can be satisfactorily described by
the excitation and radiative recombination of molecular excitons, localized at
single tri-s-triazine units. The discussed model is in accordance with the
recently reported absorption features of carbon nitride polymers. Thus, from
the point of view of optical spectroscopy, the material effectively behaves as
a monomer
Low temperature photoluminescence studies of CdTe thin films deposited on CdS ZnO glass substrates
Photophysics of polymeric carbon nitride An optical quasimonomer
A comprehensive investigation of the luminescent properties of carbon nitride polymers, based on tri-s-triazine units, has been conducted. Steady-state temperature- and excitation-power-dependent as well as time-resolved measurements with near-UV excitation (λ=325 nm and 405 nm) yield strong photoluminescence, covering the visible spectrum. The spectral, thermal, and temporal features of the photoluminescence can be satisfactorily described by the excitation and radiative recombination of molecular excitons, localized at single tri-s-triazine units. The discussed model is in accordance with the recently reported absorption features of carbon nitride polymers. Thus, from the point of view of optical spectroscopy, the material effectively behaves as a monomer
Metal Free Photocatalytic Graphitic Carbon Nitride on p Type Chalcopyrite as a Composite Photocathode for Light Induced Hydrogen Evolution
Recently, it has been shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible light irradiation in the presence of a sacrificial donor. We present herein the preparation and characterization of graphitic carbon nitride g C3N4 films on p type semiconducting CuGaSe2 chalcopyrite thin film substrates by thermal condensation of a dicyandiamide precursor under inert gas conditions. Structural and surface morphological studies of the carbon nitride films suggest a high porosity of g C3N4 thin films consisting of a network of nanocrystallites. Photoelectrochemical investigations show light induced hydrogen evolution upon cathodic polarization for a wide range of proton concentrations in the aqueous electrolyte. Additionally, synchrotron radiation based photoelectron spectroscopy has been applied to study the surface near surface chemical composition of the utilized g C3N4 film photocathodes. For the first time, it has been shown that g C3N4 films coated on p type CuGaSe2 thin films can be successfully applied as new photoelectrochemical composite photocathodes for light induced hydrogen evolutio