Graphitic carbon nitride
Encyclopedia
Graphitic carbon nitride
(g-C3N4) is a family of compounds with a general formula near to C3N4 and structures based on triazine units which, depending on reaction conditions, exhibit different degrees of condensation
, properties and reactivities.
of cyanamide
, dicyandiamide or melamine
. The firstly formed polymeric C3N4 structure, melon, with pendant amino groups, is a highly ordered polymer
. Further reaction leads to more condensed and less defective C3N4 species, based on tri-s-triazine (C6N7) units as elementary building blocks.
Graphitic carbon nitride can also be prepared by electrodeposition
on Si(100) substrate from a saturated acetone
solution of cyanuric trichloride
and melamine (ratio =1: 1.5) at room temperature.
Well-crystallized graphitic carbon nitride nanocrystallites also can be have prepared via benzene-thermal reaction between C3N3Cl3
and NaNH2
at 180–220 °C for 8–12 h.
Recently, a new method of syntheses of graphitic carbon nitrides by heating at 400-600ºC of a mixture of melamine and uric acid
in the presence of alumina has been reported. Alumina favored the deposition of the graphitic carbon nitrides layers on the exposed surface. This method can be assimilated to an in situ chemical vapor deposition
(CVD).
ring existed in the products by X-ray photoelectron spectroscopy
(XPS) measurements, photoluminescence
spectra and Fourier transform infrared spectroscopy
(FTIR) spectrum (peaks at 800 cm-1, 1310 cm-1 and 1610 cm-1).
properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene
, trimerization reactions, and also the activation of carbon dioxide
(artificial photosynthesis
).
-sized graphitic form, be used for tribological
coatings, biocompatible medical coatings, chemically inert coatings, insulators and for energy-storage solutions.
(g-C3N4) is a family of compounds with a general formula near to C3N4 and structures based on triazine units which, depending on reaction conditions, exhibit different degrees of condensation
Condensation reaction
A condensation reaction is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction; other possible small molecules lost are hydrogen chloride,...
, properties and reactivities.
Preparation
Graphitic carbon nitride can be made by polymerizationPolymerization
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
of cyanamide
Cyanamide
Cyanamide is an organic compound with the formula CN2H2. This white solid is widely used in agriculture and the production of pharmaceuticals and other organic compounds. It is also used as an alcohol deterrent drug in Canada, Europe and Japan. The molecule features a nitrile group attached to an...
, dicyandiamide or melamine
Melamine
Melamine is an organic base and a trimer of cyanamide, with a 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass and, if mixed with resins, has fire retardant properties due to its release of nitrogen gas when burned or charred, and has several other industrial uses....
. The firstly formed polymeric C3N4 structure, melon, with pendant amino groups, is a highly ordered polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
. Further reaction leads to more condensed and less defective C3N4 species, based on tri-s-triazine (C6N7) units as elementary building blocks.
Graphitic carbon nitride can also be prepared by electrodeposition
Electrodeposition
Electrodeposition may refer to:*Electroplating*Electrophoretic deposition*Underpotential deposition...
on Si(100) substrate from a saturated acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...
solution of cyanuric trichloride
Cyanuric chloride
Cyanuric chloride is the inorganic compound with the formula 3. This colorless solid is the chlorinated derivative of 1,3,5-triazine. It is the trimer of cyanogen chloride...
and melamine (ratio =1: 1.5) at room temperature.
Well-crystallized graphitic carbon nitride nanocrystallites also can be have prepared via benzene-thermal reaction between C3N3Cl3
Cyanuric chloride
Cyanuric chloride is the inorganic compound with the formula 3. This colorless solid is the chlorinated derivative of 1,3,5-triazine. It is the trimer of cyanogen chloride...
and NaNH2
Sodium amide
Sodium amide, commonly called sodamide, is the chemical compound with the formula NaNH2. This solid, which is dangerously reactive toward water, is white when pure, but commercial samples are typically gray due to the presence of small quantities of metallic iron from the manufacturing process...
at 180–220 °C for 8–12 h.
Recently, a new method of syntheses of graphitic carbon nitrides by heating at 400-600ºC of a mixture of melamine and uric acid
Uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates such as ammonium acid urate. Uric acid is created when the body breaks down purine nucleotides. High blood concentrations of uric acid...
in the presence of alumina has been reported. Alumina favored the deposition of the graphitic carbon nitrides layers on the exposed surface. This method can be assimilated to an in situ chemical vapor deposition
Chemical vapor deposition
Chemical vapor deposition is a chemical process used to produce high-purity, high-performance solid materials. The process is often used in the semiconductor industry to produce thin films. In a typical CVD process, the wafer is exposed to one or more volatile precursors, which react and/or...
(CVD).
Characterisation
Characterisation of crystalline g-C3N4 can be carried out by identifying the triazineTriazine
A triazine is one of three organic chemicals, isomeric with each other, whose molecular formula is 333 and whose empirical formula is CHN.- Structure :...
ring existed in the products by X-ray photoelectron spectroscopy
X-ray photoelectron spectroscopy
X-ray photoelectron spectroscopy is a quantitative spectroscopic technique that measures the elemental composition, empirical formula, chemical state and electronic state of the elements that exist within a material...
(XPS) measurements, photoluminescence
Photoluminescence
Photoluminescence is a process in which a substance absorbs photons and then re-radiates photons. Quantum mechanically, this can be described as an excitation to a higher energy state and then a return to a lower energy state accompanied by the emission of a photon...
spectra and Fourier transform infrared spectroscopy
Fourier transform infrared spectroscopy
Fourier transform infrared spectroscopy is a technique which is used to obtain an infrared spectrum of absorption, emission, photoconductivity or Raman scattering of a solid, liquid or gas. An FTIR spectrometer simultaneously collects spectral data in a wide spectral range...
(FTIR) spectrum (peaks at 800 cm-1, 1310 cm-1 and 1610 cm-1).
Properties
Due to the special semiconductorSemiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
, trimerization reactions, and also the activation of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
(artificial photosynthesis
Artificial photosynthesis
Artificial photosynthesis is a chemical process that replicates the natural process of photosynthesis, a process that converts sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term is commonly used to refer to any scheme for capturing and storing the energy from sunlight in...
).
Uses
A commercial graphitic carbon nitride available under the brand name Nicanite® can, in its micronMicron
Micron can refer to:*Micron, a non-SI name for micrometre*Micron , is the measurement used to express the diameter of a wool fibre.*A small curved diacritic mark above some letters, used to indicate shortness, e.g...
-sized graphitic form, be used for tribological
Tribology
Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear...
coatings, biocompatible medical coatings, chemically inert coatings, insulators and for energy-storage solutions.