Cyano-Rich g-C3 N4 in Photochemistry: Design, Applications, and Prospects

Cyano-rich g-C3 N4 materials are widely used in various fields of photochemistry due to the very powerful electron-absorbing ability and electron storage function of cyano, as well as its advantages in improving light absorption, adjusting the energy band structure, increasing the polarization rate and electron density in the structure, active site concentration, and promoting oxygen activation ability. Notwithstanding, there is yet a huge knowledge break in the design, preparation, detection, application, and prospect of cyano-rich g-C3 N4 . Accordingly, an overall review is arranged to substantially comprehend the research progress and position of cyano-rich g-C3 N4 materials. An overall overview of the current research position in the synthesis, characterization (determination of their location and quantity), application, and reaction mechanism analysis of cyano-rich g-C3 N4 materials to provide a quantity of novel suggestions for cyano-modified carbon nitride materials' construction is provided. In view of the prevailing challenges and outlooks of cyano-rich g-C3 N4 materials, this paper will purify the growth direction of cyano-rich g-C3 N4 , to achieve a more in-depth exploration and broaden the applications of cyano-rich g-C3 N4 .

Tube wall delamination engineering induces photogenerated carrier separation to achieve photocatalytic performance improvement of tubular g-C3N4

Morphology adjustment is a feasible method to change the physicochemical properties of photocatalysts. The issue that excessively thick tube wall of tubular g-C₃N₄ is not conducive to the electron migration from inside to the surface thus inhibiting the separation of photogenerated carriers has always been ignored. Potassium ions were used to regulate the structure of the tubular supramolecular precursor by breaking hydrogen bonds, thereby promoting the synthesis of delaminated laminar tubular g-C₃N₄ (K-CN), which not only shortened the transfer distance of photogenerated electrons but also provided abundant reaction active sites. Experiments and DFT calculations were combined to reveal the details of the physicochemical properties of K-CN. The photocatalytic capacity of K-CN for tetracycline hydrochloride (TCH) degradation and H₂O₂ generation were 83% and 133 μM, respectively. This work not only synthesized a novel delaminated tubular g-C₃N₄ but also provided a strategy and inspiration for structure and performance optimization for tubular g-C₃N₄.

Construction of C@WS2/g-C3N4 Z-scheme photocatalyst with C film as an effective electron mediator and its enhanced degradation of 2,4-dichlorophenol under visible light

A novel Z-scheme heterojunction C@WS₂/g-C₃N₄ composite was prepared with carbon as a bridge for improving the photocatalytic property. The results of composition and structure studies demonstrate that the introduced carbon was deposited on the surface of WS₂ with a film form in the ternary composites. The analysis of optical and photo-electrochemical properties reveals that the carbon film played as an electron-mediator in the ternary composites and could improve the separation and transportation of photogenerated charge. Meanwhile, it could change the pathway of photogenerated electrons between WS₂ and g-C₃N₄, thereby constructing a Z-scheme heterojunction for maintaining the redox ability of photogenerated charge. The ternary 2%-C@WS₂/g-C₃N₄ composite exhibited an excellent photodegradation rate towards 2,4-dichlorophenol (2,4-DCP) under visible light irradiation, which was 3.15 and 3.06 times of the pure g-C₃N₄ and binary WS₂/g-C₃N₄ composite, respectively. Besides, the degradation pathway of 2,4-DCP and photocatalytic degradation mechanisms were investigated and discussed in detail. The generated ·O₂^--, ·OH and h⁺ by ternary composites could promote the dechlorination reaction of 2,4-DCP effectively and decompose it into smaller organic molecules. This work extends the design of g-C₃N₄-based 2D/2D heterojunction or Z-scheme photocatalysts to remediate the environment.

Graphitic carbon nitride nanotubes: a new material for emerging applications

We provide a critical review of the current state of the synthesis and applications of nano- and micro-tubes of layered graphitic carbon nitride. This emerging material has a huge potential for light-harvesting applications, including light sensing, artificial photosynthesis, selective photocatalysis, hydrogen storage, light-induced motion, membrane technologies, and can become a major competitor for such established materials as carbon and titania dioxide nanotubes. Graphitic carbon nitride tubes (GCNTs) combine visible-light sensitivity, high charge carrier mobility, and exceptional chemical/photochemical stability, imparting this material with unrivaled photocatalytic activities in photosynthetic processes, such as water splitting and carbon dioxide reduction. The unique geometric GCNT structure and versatility of possible chemical modifications allow new photocatalytic applications of GCNTs to be envisaged including selective photocatalysts of multi-electron processes as well as light-induced and light-directed motion of GCNT-based microswimmers. Closely-packed arrays of aligned GCNTs show great promise as multifunctional membrane materials for the light energy conversion and storage, light-driven pumping of liquids, selective adsorption, and electrochemical applications. These emerging applications require synthetic routes to GCNTs with highly controlled morphological parameters and composition to be available. We recognize three major strategies for the GCNT synthesis including templating, supramolecular assembling of precursors, and scrolling of nano-/microsheets, and outline promising routes for further progress of these approaches in the light of the most important emerging applications of GCNTs.

Supramolecular Copolymerization Strategy for Realizing the Broadband White Light Luminescence Based on N-Deficient Porous Graphitic Carbon Nitride (g-C3N4)

The N-deficient porous g-C₃N₄ with broadband white light emission was constructed by supramolecular copolymerization design, which combined organic copolymers cyanuric acid and 2,4,6-triaminopyrimidine with melamine upon the mixture gas environment of (95%)N₂/(5%)H₂. Herein, we achieved great breakthrough in narrowing the band gap of g-C₃N₄ from 2.64 to 1.39 eV. Furthermore, in contrast to pristine g-C₃N₄, we demonstrated that the emission wavelengths of N-deficient porous g-C₃N₄ can be tuned from narrow blue to broadband white range, where the optimal white light coordinate position is (0.297, 0.345). The prepared N-deficient porous g-C₃N₄ overcomes the limitation of the narrow adjusting range of optical properties while using conventional g-C₃N₄ and makes it more promising for applications in solid-state displays.