Research development on graphitic carbon nitride and enhanced catalytic activity on ammonium perchlorate

Understanding Structure-Activity Relationship in Pt-loaded g-C3 N4 for Efficient Solar- Photoreforming of Polyethylene Terephthalate Plastic and Hydrogen Production

Coupling the hydrogen evolution reaction with plastic waste photoreforming provides a synergistic path for simultaneous production of green hydrogen and recycling of post-consumer products, two major enablers for establishment of a circular economy. Graphitic carbon nitride (g-C3 N4 ) is a promising photocatalyst due to its suitable optoelectronic and physicochemical properties, and inexpensive fabrication. Herein, a mechanistic investigation of the structure-activity relationship of g-C3 N4 for poly(ethylene terephthalate) (PET) photoreforming is reported by carefully controlling its fabrication from a subset of earth-abundant precursors, such as dicyandiamide, melamine, urea, and thiourea. These findings reveal that melamine-derived g-C3 N4 with 3 wt.% Pt has significantly higher performance than alternative derivations, achieving a maximum hydrogen evolution rate of 7.33 mmolH2  gcat -1  h-1 , and simultaneously photoconverting PET into valuable organic products including formate, glyoxal, and acetate, with excellent stability for over 30 h of continuous production. This is attributed to the higher crystallinity and associated chemical resistance of melamine-derived g-C3 N4 , playing a major role in stabilization of its morphology and surface properties. These new insights on the role of precursors and structural properties in dictating the photoactivity of g-C3 N4 set the foundation for the further development of photocatalytic processes for combined green hydrogen production and plastic waste reforming.

Facile synthesis of MgCo2O4 nanosheets and its catalysis effect on the decomposition of ammonium perchlorate

The catalysis effects of MgCo2O4 nanosheets on the thermal decomposition of ammonium perchlorate (AP) were investigated. The MgCo2O4 nanosheets were synthesized with a facile free-template hydrothermal method. The chemical structure and micro morphology of MgCo2O4 nanosheets were characterized. Moreover, the catalysis thermal decomposition properties of AP using composite metal oxides MgCo2O4 nanosheets with different contents (1wt%, 3wt%, and 5wt%) as catalysts were investigated. The results showed that the reducing decomposition temperature of AP was 155.9 °C from 431 °C to 275.1 °C with 5wt% MgCo2O4 added. The heat release of AP was increased of 907 J/g at least. In addition, the catalysis thermal decomposition mechanism of AP with the existence of MgCo2O4 nanosheets was explained. With the increasing temperature, the accumulated electrons (e-) and holes (h+) excited was activated at the surface of MgCo2O4 nanosheets, which accelerated H transfer from H atom of NH4+ to O atom of ClO4- and boosted AP decomposition.

Improved polyhydroxybutyrate production by Cupriavidus necator and the photocatalyst graphitic carbon nitride from fructose under low light intensity

The photocatalyst graphitic carbon nitride (g-C₃N₄) is known to photostimulate the production of the bioplastic polyhydroxybutyrate (PHB) by Cupriavidus necator. In previous studies, the combination of C. necator and g-C₃N₄ increased PHB yield from either an organic or inorganic carbon substrate under a light intensity of 4200 lx. Here, different parameters including light intensity, pH, temperature, nitrogen and carbon concentrations, aeration, and inoculum size were explored to maximize PHB production by hybrid photosynthesis from fructose and visible light. A g-C₃N₄/C. necator culture grown with a lower light intensity of 2100 lx, an inoculum size of 128.30 × 10⁶ CFU ml^-1, and constant aeration produced 7.16 g l^-1 d^-1 PHB with a product yield from fructose of 60.94%. Furthermore, the ratio of incident photons harvested by g-C₃N₄ converted into NADPH+H⁺ by C. necator for PHB production was improved to 19.74% after the process optimization. In comparison, the PHB production rate of a non-optimized g-C₃N₄/C. necator system exposed to 4200 lx was only 2.94 g l^-1 d^-1 with a product yield from fructose of 33.29%. These results demonstrate that hybrid photosynthesis productivity can be significantly augmented by decreasing light intensity and adjusting other parameters, which is promising for future bioproduction applications.

Facile Preparation of Carbon Nitride-ZnO Hybrid Adsorbent for CO2 Capture: The Significant Role of Amine Source to Metal Oxide Ratio

The presence of CO2 in gaseous fuel and feedstock stream of chemical reaction was always considered undesirable. High CO2 content will decrease quality and heating value of gaseous fuel, such as biohydrogen, which needs a practical approach to remove it. Thus, this work aims to introduce the first C3N4-metal oxide hybrid for the CO2 cleaning application from a mixture of CO2-H2 gas. The samples were tested for their chemical and physical properties, using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), physical adsorption analysis (BET), fourier-transform infrared (FTIR), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The CO2 capacity test was carried out by means of a breakthrough test at 1 atm and 25° C using air as a desorption system. Among the samples, amine/metal oxide mass ratio of 2:1 (CNHP500-2(2-1)) showed the best performance of 26.9 wt. % (6.11 mmol/g), with a stable capacity over 6 consecutive cycles. The hybrid sample also showed 3 times better performance than the raw C3N4. In addition, it was observed that the hydrothermal C3N4 synthesis method demonstrated improved chemical properties and adsorption performance than the conventional dry pyrolysis method. In summary, the performance of hybrid samples depends on the different interactive factors of surface area, pore size and distribution, basicity, concentration of amine precursors, ratio of amines precursors to metal oxide, and framework stability.