Tailoring the Morphology of g‐C₃N₄ by Self‐Assembly towards High Photocatalytic Performance

Abstract

We report a novel method for the preparation of graphitic carbon nitride (g‐C3N4) with various morphologies through self‐assembly and calcination, which starts from the raw materials melamine, urea, and cyanuric acid. The hollow to wormlike morphologies of g‐C3N4 could be readily tailored by adjusting the molar ratio of melamine to urea; with increase in the molar ratio from 3:1 to 1:3, a morphology transformation was observed. The morphologies were tailored by self‐assembly of the aggregates by hydrogen bonding and ionic interactions. Correspondingly, an increased BET surface area from 49.6 to 97.4 m2 g−1 was observed. If used as a photocatalyst in degrading rhodamine B (RhB) under visible‐light irradiation, these g‐C3N4 samples demonstrated 7 to 13 times higher performance than conventional bulk g‐C3N4. The high performance was attributed to the unique morphology that provided not only high specific surface area but low recombination losses of photogenerated charges.

Facile Synthesis of Crystalline Polymeric Carbon Nitrides with an Enhanced Photocatalytic Performance under Visible Light

“…Various strategies that include doping with heteroatoms (F, I, B, P, S, O, etc. ),5 increasing the specific surface area,5f, 6 combining with other semiconductors,7 and constructing different nanostructures3b, 4a, 8 have been proposed to address this problem. In addition, poly(triazine imides) intercalated with Li + and Cl − (PTI/Cl), which is described as a crystalline polymeric carbon nitride, may also overcome the drawbacks of g‐C 3 N 4 9.…”

Phenyl‐Modified Carbon Nitride Quantum Dots with Distinct Photoluminescence Behavior

“…Thus far, the maximum reported Stokes shift for CN is 130 nm, whereas values of 100 nm are commonly observed, and there is significant overlap between the absorption and emission spectra. [4a] Recently,w eh ave developed as upramolecular preorganization approach to template the structure and improve the photocatalytic activities of CN.[6] Thee lectronic and optical properties of the final CN materials can be optimized by the careful design and selection of the supramolecular starting complex;f or example,t he use of ac yanuric acid/melamine assembly also enables the integration of other molecules,such as barbituric acid, [7] urea, [8] and even caffeine. [9] We also showed the power of this method by using ac omplex with phenyl-substituted triazines to grow modified CN thin films as the active layers in solar cells and light-emitting diodes, [10] applications that rely on the control of the band structure and the emission properties.…”

“Caffeine Doping” of Carbon/Nitrogen‐Based Organic Catalysts: Caffeine as a Supramolecular Edge Modifier for the Synthesis of Photoactive Carbon Nitride Tubes

“…Up to now, the supramolecular complexes were built by interaction of two or more monomers, connected by hydrogen bonds, in different solvents, whereas all the reported monomers allowed full integration into the structure (with infinite repeating units), however, without considering termination and edges 16. 17 The introduction of new monomers as “growth stoppers” or “edge‐termination agents” in the supramolecular complex structure is expected to be an effective method to control the C 3 N 4 morphologies and electronic properties further. As the catalytic activities of sheetlike molecules as all‐carbon graphenes or carbon nitride are expected to be related to the designed exposure of edges,18 C 3 N 4 structures built with this new edge‐lining molecule should exhibit altered charge localization sites and/or promote more efficient charge transfer.…”