Co2+ immobilized on highly ordered mesoporous graphitic carbon nitride (ompg-C3N4/Co2+) as an efficient and recyclable heterogeneous catalyst for one-pot tandem selective photo-oxidation/Knoevenagel condensation

Investigation of NaCl-Modified Graphitic Carbon Nitride for Efficient Biodiesel Production from Waste Oil via Transesterification: A Box-Behnken Design Approach

NaCl-modified graphitic carbon nitrides (GCN) were applied in the base-catalyzed transesterification of recovered oil. GCN has been seen as a prospective heterogeneous catalyst for transesterification, but pristine-GCN has a narrow range of applications because of its weak basic sites and small surface area. To overcome these defects, NaCl-modified GCN was prepared through the co-thermal polymerization of NaCl with urea. The doping of NaCl generated C≡N and Na-N species, which enhanced the basicity of the catalyst. Meanwhile, with the assistance of NaCl, GCN was decomposed and produced a large number of small pores of hundreds of nanometers, which contributed to the increase in specific surface area. In addition, the effects of transesterification parameters and their interactions on biodiesel yields were investigated by using Box-Behnken design, and the reaction conditions were optimized. A high biodiesel yield of 93.05% was achieved under the optimal conditions.

Organocatalysis with carbon nitrides

Carbon nitrides, a distinguished class of metal-free catalytic materials, have presented a good potential for chemical transformations and are expected to become prominent materials for organocatalysis. This is largely possible due to their low cost, exceptional thermal and chemical stability, non-toxicity, ease of functionalization, porosity development, etc. Especially, the carbon nitrides with increased porosity and nitrogen contents are more versatile than their bulk counterparts for catalysis. These N-rich carbon nitrides are discussed in the earlier parts of the review. Later, the review highlights the role of such carbon nitride materials for the various organic catalytic reactions including Knoevenagel condensation, oxidation, hydrogenation, esterification, transesterification, cycloaddition, and hydrolysis. The recently emerging concepts in carbon nitride-based organocatalysis have been given special attention. In each of the sections, the structure-property relationship of the materials was discussed and related to their catalysis action. Relevant comparisons with other catalytic materials are also discussed to realize their real potential value. The perspective, challenges, and future directions are also discussed. The overall objective of this review is to provide up-to-date information on new developments in carbon nitride-based organic catalysis reactions that could see them rising as prominent catalytic materials in the future.

Polymer Brushes on Graphitic Carbon Nitride for Patterning and as a SERS Active Sensing Layer via Incorporated Nanoparticles

Graphitic carbon nitride (gCN) has a broad range of promising applications, from energy harvesting and storage to sensing. However, most of the applications are still restricted due to gCN poor dispersibility and limited functional groups. Herein, a direct photografting of gCN using various polymer brushes with tailorable functionalities via UV photopolymerization at ambient conditions is demonstrated. The systematic study of polymer brush-functionalized gCN reveals that the polymerization did not alter the inherent structure of gCN. Compared to the pristine gCN, the gCN-polymer composites show good dispersibility in various solvents such as water, ethanol, and tetrahydrofuran (THF). Patterned polymer brushes on gCN can be realized by employing photomask and microcontact printing technology. The polymer brushes with incorporated silver nanoparticles (AgNPs) on gCN can act as a multifunctional recyclable active sensing layer for surface-enhanced Raman spectroscopy (SERS) detection and photocatalysis. This multifunctionality is shown in consecutive cycles of SERS and photocatalytic degradation processes that can be applied to in situ monitor pollutants, such as dyes or pharmaceutical waste, with high chemical sensitivity as well as to water remediation. This dual functionality provides a significant advantage to our AgNPs/polymer-gCN with regard to state-of-the-art systems reported so far that only allow SERS pollutant detection but not their decomposition. These results may provide a new methodology for the covalent functionalization of gCN and may enable new applications in the field of catalysis, biosensors, and, most interestingly, environmental remediation.

Major advances in the development of ordered mesoporous materials

This feature article presents the main developments in the area of ordered mesoporous materials (OMMs) since their discovery in 1992, which is considered one of the milestones in the history of porous materials.