Thermal stability of polymeric carbon nitride (PCN)-Al2O3–ZrO2 nanocomposites used in photocatalysis

Abstract

Polymeric carbon nitride (PCN) was recently found to have extensive applications in the field of photocatalysis. Knowledge about thermal stability of PCN nanocomposites is crucial for this application and designing the final product. In this work, the thermal stability of PCN-Al2O3–ZrO2 nanocomposites was investigated. PCN nanocomposites were obtained in two steps: (1) microwave hydrothermal synthesis of co-precipitated AlOOH and ZrO2 precursors, followed by drying; (2) mixing the nanopowders with melamine powder and annealing in air in a tube furnace at 400, and 450 °C. The PCN nanocomposites were examined by attenuated total reflection technique of Fourier transformed infrared spectroscopy. Also, the evolved gas analysis was performed combining differential scanning calorimetry and thermogravimetry coupled with mass spectroscopy and FTIR. The results show that only PCN-Al2O3–ZrO2 nanocomposite obtained at 400 °C is stable from room temperature up to 490 °C and during thermal decomposition, in one step releases ammonia (NH3), cyanic acid (HNCO), water (H2O), and carbon dioxide (CO2). The limitation of the PCN-Al2O3–ZrO2 thermal stability and performance is AlOOH–ZrO2 used as a nanocomposite component.

Thermal properties and decomposition mechanism of disubstituted fused 1,2,4-triazoles considered as potential anticancer and antibacterial agents

“…The characteristic absorption bands for ammonia are appeared as two signals at 931 cm −1 and 966 cm −1 connecting with the N-H deformation vibrations and as the signals at ca. 3350 cm −1 derived from the N-H stretching vibrations [25][26][27][28]. Apart from the emission of NH 3 during the first decomposition stage, the evolution of HCN molecule is also observed.…”

Application of Simultaneous and Coupled Thermal Analysis Techniques in Studies on the Melting Process, Course of Pyrolysis and Oxidative Decomposition of Fused Triazinylacetohydrazides

“…Figure 7 shows the gaseous FTIR spectra obtained during heating of the tested annelated triazinylacetohydrazides and collected at Tmax1, Tmax1a, Tmax2 and Tmax3 in oxidative conditions. As is well visible, from T 5% to T max1a , the emission of NH 3 due to the presence of two characteristic absorption bands at 931 cm −1 and at 966 cm −1 , describing the deformation vibrations of N-H groups [22][23][24][25] at the gaseous FTIR spectra, and m/z ions 15 (NH + ) and 17 (NH 3 + ) at the QMS spectra is clearly confirmed. Together with the ammonia, the creation of some of the nitrogen oxides is documented.…”

“…The gaseous FTIR spectra obtained during heating of the analysed compounds and collected at T max1 , T max1a , T max1b and T max2 in inert conditions are presented in Figure 4. At T max1 , there is the attendance of two absorption peaks at 931 cm −1 and at 966 cm −1 that are characteristic bands for the emission of NH 3 (deformation vibrations of N-H groups [22][23][24][25]). The formation of HNCO by the presence of the absorption peaks at 2270-2290 cm −1 [22,26,27] is confirmed.…”

Thermal Decomposition Path—Studied by the Simultaneous Thermogravimetry Coupled with Fourier Transform Infrared Spectroscopy and Quadrupole Mass Spectrometry—Of Imidazoline/Dimethyl Succinate Hybrids and Their Biological Characterization

“…(2) At Tmax2a, the emission of HCN (713 cm −1 ), NH3 (the presence of the deformation vibrations of the N-H groups at 931 cm −1 and 966 cm −1 [27][28][29][30][31][32]), CO2 (bands at 2300-2365 cm −1 (valence vibration) and 669 cm −1 (deformation vibration)), HNCO (bands at 2270-2290 cm −1 ), H2O (several, jagged, weak bands in the range of 3450-4000 cm −1 ), aromatic amines, and carbonyl compounds is well visible from the gaseous FTIR spectra. If we look at the initial structure of the tested compounds, the presence of HNCO as the de- The obtained FTIR results are also confirmed based on the QMS analyses.…”

“…However, the structure of the formed intermediates in polymerization processes or other chemical reactions during the heating of the tested compounds and the presence of m/z ions 28 (N2 + ) and 14 (N + ) in the QMS spectrum suggest the emission of nitrogen. At T max2a , the emission of HCN (713 cm −1 ), NH 3 (the presence of the deformation vibrations of the N-H groups at 931 cm −1 and 966 cm −1 [27][28][29][30][31][32]), CO 2 (bands at 2300-2365 cm −1 (valence vibration) and 669 cm −1 (deformation vibration)), HNCO (bands at 2270-2290 cm −1 ), H 2 O (several, jagged, weak bands in the range of 3450-4000 cm −1 ), aromatic amines, and carbonyl compounds is well visible from the gaseous FTIR spectra. If we look at the initial structure of the tested compounds, the presence of HNCO as the decomposition product is unexpected.…”