Roberto C. Dante

Polymeric Carbon Nitride Nanosheets

Polymeric carbon nitride was synthesized by polycondensation in a nitrogen flux using melamine cyanurate as a reagent and sulfuric acid as a catalyst. The product was polymeric-graphitic carbon nitride based on heptazine units. The carbon nitride was composed of nanosheet flakes. This synthesis method seems to be a suitable pathway toward carbon nitride graphene formation.

Synthesis under Pressure of Potential Precursors of CNx Materials Based on Melamine and Phenolic Resins

The cross-linking under pressure of a mixture of novolak and melamine resins with a weight ratio of 1 has been investigated by means of several techniques, including DSC, TGA, XRD, and IR. Four samples were prepared under varying pressure and temperature. The application of pressure to the reaction vessel favored the formation of a more structured cross-linked resin. The sample cross-linked at both the highest temperature and pressure levels exhibited higher structuring effects than the others. Moreover, this sample exhibited much higher thermal stability than the others. This achievement may allow us to open the pathway toward new precursors of structured CN x materials.

Composite Fiber Based on Sisal Fiber and Calcium Carbonate

The impregnation of a raw sisal fiber in a saturated solution of calcium hydroxide generated a fiber coated by a remarkable quantity of calcium carbonate and calcium oxide. However, some detachments of the inorganic coating were observed at microscopic level, and interstices in the external walls, filled by the precipitated material, were less visible than in raw fiber. Additionally, some fiber components have been removed by the preliminary sodium silicate washing. The final composite exhibited more amorphous characteristics than the original raw fiber, as well as its mechanical behavior was very similar to an elastomeric material with more homogeneous mechanical properties than the original raw fiber.

Molecular dynamics simulations of nanosheets of polymeric carbon nitride and comparison with experimental observations

ABSTRACT A computational study of the properties of polymeric carbon nitride using molecular dynamics is presented. The analysis of ideal infinite-extent sheets permits to evaluate the effect of temperature on the network of hydrogen bonds responsible for the linkage of the material. The weakening of this binding mechanism at sufficiently high temperatures, together with the inter-layer interactions characteristic of this type of 2D materials, is shown to determine the conformation properties of polymeric carbon nitride at the nanoscale. The results obtained from the simulation of finite samples in the canonical ensemble at varying temperatures are consistent with those from the characterization of our experimentally synthesized samples. Hydrogen bonding between adjacent polymer ribbons leads this process and is the cause of the typical crumpled structure of this material.

Photocatalytic activity of a new composite material of Fe (III) oxide nanoparticles wrapped by a matrix of polymeric carbon nitride and amorphous carbon

ABSTRACT Polymeric carbon nitride was synthesized from urea and doped with Cu and Fe to act as co-catalysts. The material doped with Fe was a new composite material composed of Fe(III) oxides (acting as a co-catalyst) wrapped by the polymer layers and amorphous carbon. Furthermore, the copper doped material was described in a previous report. The photocatalytic degradation of the azo dye direct blue 1 (DB) was studied using as photocatalysts: pure carbon nitride (CN), carbon nitride doped with Cu (CN-Cu) and carbon nitride doped with Fe (CN-Fe). The catalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), by X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller method (BET), etc. The adsorption phenomenon was studied using the Langmuir and Freundlich models. For the kinetic study, a solution of 500 mg L−1 of DB1 was treated with each catalyst, visible light and H2O2. The dye concentration was measured by spectrophotometry at the wavelength of 565 nm, and the removal of the total organic content (TOC) was quantified. BET analysis yielded surface areas of 60.029, 20.116 and 70.662 m2g−1 for CN, CN-Cu and CN-Fe, respectively. The kinetics of degradation were pseudo-first order, whose constants were 0.093, 0.039 and 0.110 min−1 for CN, CN-Cu and CN-Fe, respectively. The total organic carbon (TOC) removal reached the highest value of 14.46% with CN-Fe.

Copper complexes within the supramolecular solid structure of cyanuric acid and melamine

ABSTRACT A complex of copper sulfate was formed by impregnation of the cyanuric acid melamine adduct (CAM) with a solution of copper (II) sulfate. A thermal treatment at 250°C of the dried compound delivered a greenish powder. The UV-Vis spectroscopy showed that an absorption around 700 nm is compatible with a copper (II) sulfate complex coordinated inside the supramolecular structure of CAM. No copper or copper oxide particles were found by means of either transmission or scanning electron microscopy. X-ray photoelectron spectroscopy showed that on the surface there was a considerable amount of Cu(I) (66%) probably coordinated also inside the CAM channels. A brief catalytic test showed the ability of the copper complexes to oxidize sucrose to gluconic acid.