Raman spectroscopy is a nondestructive and in situ analytical technique that could provide information on the chemical structure and structural ordering of carbonaceous materials. Based on theE(2g)symmetric stretching vibration mode in the aromatic layers (G band, ~1,580 cm(-1)) and the defect structure in graphite (D band, ~1,350 cm(-1)), Raman spectroscopy has been used extensively to characterize the structural features of carbonaceous matters since 1970. Coal is a complex organic compound made up mainly by carbon showing characteristic Raman bands. This article reviews the application of Raman spectroscopy for coal structure characterization under room temperature, to determine its chemical structure, crystallite size, coal rank, and combustion reactivity. Future research for collecting Raman spectra during coal pyrolysis at high temperatures is also discussed. The combination of high-temperature hot stage with Raman spectroscopy technology allows direct collection of Raman spectra at high temperature.

The comfortable, beautiful and healthy residential environment has been a target pursued by human beings. However, the inevitable presences of indoor air pollutants such as nicotine which release from tobacco smoking imperceptibly invade people's health. Here, we developed new pigments consisted by colorful graphitic carbon nitride (g-C3N4)-based catalysts, which were fabricated by facile calcining and water bath refluxing procedures. The catalytic pigments exhibited a high catalytic activity for the removal of nicotine under sunlight or even light emitting diode (LED). The designed experiments revealed that superoxide radicals (O-center dot(2)-) were main active species in g-C3N4-based catalysts system and played a significant role in removing contaminants. Noteworthy, the catalysts as pigments were successfully used for coloring textiles and painting. Both the catalytic textiles and paintings were provided with preferably photocatalytic performance and reusability. The catalytic pigments were simple to prepare, brightly colored and could effectively degrade nicotine, thus not only have decorative effect, enriching the spiritual world, but also contribute to the protection of the environment of human life.

As highly active species, in theory, hydroxyl radicals ((OH)-O-center dot) can move freely and destroy almost all organic compounds, including catalysts with a conjugate structure. Therefore, a system that can generate oxidative species with a high activity, but where the active species is anchored to avoid autooxidation, is urgently required. In this work, we fabricated a novel visible-light-assisted advanced oxidation process based on high-valent iron species (Fe(IV)=O) over graphitic carbon nitride (g-C3N4) that was coordinated to iron hexadecachlorophthalocyanine (FePcCl16) through imidazole ligands (IMD). Under visible-light excitation, the phthalocyanine ring of the g-C3N4-IMD-FePcCl16/hydrogen peroxide (H2O2) can be motivated to an excited state FePcCl/(16)*, in which active H2O2 and the generation of anchored Fe(IV)=O species are used for the degradation of carbamazepine (CBZ). Because the molecular movement of transient Fe (IV)=O species is restricted, the possibility of oxidative collision is minimized, which provides good stability. An analysis of the electron paramagnetic resonance, gas chromatography/mass spectrometry, photoluminescence spectra, periodic on/off photocurrent density response and the photo-assisted catalytic active experiments, indicates that the rapid generation of Fe(IV)=O species occurs as the catalyst contacts the H2O2, which inhibits the conduction-band electrons of the g-C3N4 from reacting with H2O2 and generating (OH)-O-center dot. This study provides insight into the construction of suitable structures that will enhance visible-light-assisted catalytic oxidation activity and allow for the fabrication of an anchored highly active species. (C) 2017 Elsevier B.V. All rights reserved.

In nature, metalloporphyrins, such as chlorophyll, cytochrome P450 and so forth, are key materials in maintaining the ecological cycles, especially the carbon cycle, and play an important role in both photosynthesis and the catalytic oxidation of organisms. Inspired by these factors, we skillfully combined photocatalysis and biomimetic catalysis using imidazole (IMD)-functionalized modification of g-C3N4 and axial coordination with hemin. Compared with pure hemin, g-C3N4 and a mixture of the two, our novel catalytic system (g-C3N4-IMD-hemin/H2O2) showed high photocatalytic oxidation activity for the degradation of 4-chlorophenol (4-CP), and the stability of hemin was enhanced under solar irradiation. Furthermore, the effect of pH and the sustained photocatalytic oxidation stability of g-C3N4-IMD-hemin for degrading 4-CP were investigated. The results indicated that g-C3N4-IMD-hemin presents a high photocatalytic oxidation activity over a wide pH range and exhibits good recyclability. A series of designed experiments showed that superoxide radicals (O-center dot(2)-), high-valent iron (Fe(IV)= O) species, peroxy radicals ((OOH)-O-center dot) and few hydroxyl radicals ((OH)-O-center dot) were generated in the g-C3N4-IMD-hemin/H2O2 system. This synergistic photocatalytic and biomimetic process offers new insight for the utilization of solar energy and offers a new perspective for the exploration of catalysts for environmental remediation. (C) 2016 Elsevier B.V. All rights reserved.

The effective elimination of micropollutants by an environmentally friendly method has received extensive attention recently. In this study, a photocatalyst based on polyacrylonitrile (PAN)-supported graphitic carbon nitride coupled with zinc phthalocyanine nanofibers (g-C3N4/ZnTcPc/PAN nanofibers) was successfully prepared, where g-C3N4/ZnTcPc was introduced as the catalytic entity and the PAN nanofibers were employed as support to overcome the defects of easy aggregation and difficult recycling. Herein, rhodamine B (RhB), 4-chlorophenol and carbamazepine (CBZ) were selected as the model pollutants. Compared with the typical hydroxyl radical-dominated catalytic system, g-C3N4/ZnTcPc/PAN nanofibers displayed the targeted adsorption and degradation of contaminants under visible light or solar irradiation in the presence of high additive concentrations. According to the results of the radical scavenging techniques and the electron paramagnetic resonance technology, the degradation of target substrates was achieved by the attack of active species, including photogenerated hole, singlet oxygen, superoxide radicals and hydroxyl radicals. Based on the results of ultra-performance liquid chromatography and mass spectrometry, the role of free radicals on the photocatalytic degradation intermediates was identified and the final photocatalytic degradation products of both RhB and CBZ were some biodegradable small molecules.

For powder catalysts to be recycled easily and to be applied in practical wastewater treatment, it is imperative to search suitable carriers that can be applied to support catalytic particles. Herein, we highlight a facile route to synthesize an easily recycled photocatalyst using polyethylene terephthalate (PET) to disperse graphitic carbon nitride (g-C3N4) via electrospinning and subsequent hydrothermal treatment. The resultant nanofiber is labeled T-g-C3N4/PET. The design concept is to expose the g-C3N4 on the PET surface and convert it from inactivation to re-emergence. g-C3N4 is embedded into the PET, which avoids the reunion and unrecyclable deficiencies of powder catalysts. T-g-C3N4/PET was characterized by field-emission scanning electronic microscopy, transmission electron microscopy, UV vis diffuse reflectance spectra, two-dimensional X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis technologies. T-g-C3N4/PET showed a high photocatalytic activity for the degradation of antibiotics such as sulfaquinoxaline and sulfadiazine under solar irradiation, and the activity was almost unaffected in a high background. The as-obtained catalysts could be reused several times with no loss in performance in cycling photodegradation tests. Finally, a possible pathway and mechanism for degrading sulfaquinoxaline with T-g-C3N4/PET was proposed, respectively, in which holes and the superoxide radical were the predominant active species, and resulted in the oxidative degradation of antibiotics. These results demonstrate that the preparation method may provide a novel idea for supporting nanoscale catalysts for reuse.