Tremendous boost in the photocatalytic properties of g-C₃N₄: regulation from polymerization kinetics to crystal structure engineering

Abstract

Graphite carbon nitride (g-C3N4) has become research hotspot owing to its special electronic structure and excellent chemical stability. Although g-C3N4 has made great progress in the field of photocatalysis, its...

Small variation induces a big difference: the effect of polymerization kinetics of graphitic carbon nitride on its photocatalytic activity

“…[3][4][5] During thermal condensation, the self-generated NH 3 atmosphere will serve as a key kinetic factor to affect the subsequent deamination polymerization. 32,33 We have demonstrated that the prepared g-CN samples exhibit remarkably different photocatalytic activities even under nearly identical synthesis conditions. Although the bulk crystallinity and chemical structures of the samples revealed by XRD and FTIR are very similar (Fig.…”

“…The thermal condensation from melamine to g-CN is deamination polymerization, and the released NH 3 will generate a partial pressure in the reactor, kinetically suppressing the subsequent polymerization process. [32][33][34] The generated NH 3 partial pressure could establish a dynamic equilibrium due to its relatively slow diffusion in static air, retarding the polymerization and concurrently facilitating the decomposition of the primary C-N-H condensates, whereas in flowing air the released NH 3 will be continuously taken away, and thus the following deamination polymerization could occur more sufficiently; meanwhile, the decomposition process would be correspondingly suppressed. As a result, the synthesized CNair possesses a lower production yield as well as a larger SSA than that of CN-air-flow.…”

“…32 This reaction process is kinetically complicated and accompanied by rearrangement of the hydrogen-bonding networks, sublimation of the precursor molecules, deamination polycondensation and simultaneous decomposition of the primary condensates. 32,33 The released NH 3 will produce a supplementary self-generated atmosphere, affecting the subsequent polymerization process. 34 Song et al reported a self-modified g-CN by stopping the entrance of N 2 gas during the synthesis, achieving a degradation efficiency of rhodamine B (RhB) 7.3 times higher than the conventional sample.…”

Enhanced photocatalytic activity of single-atom Au1/TiO2 catalysts prepared using cold plasma

“…[8][9][10][11] However, conventional photocatalysts suffer from a narrow photoresponse range, extremely easy complexation of photogenerated electron-hole pairs, and limited active sites for photocatalytic reactions. [12][13][14] Therefore, the development of efficient and stable photocatalysts to eliminate organic pollution has become an important issue in environmental remediation.…”

Elucidating the Effect of Crystallinity on the Photoactivity in Poly(heptazine imides)

“…Crystalline carbon nitride materials (CNs), such as poly­(heptazine imides) (PHI) and poly­(triazine imide) (PTI), have emerged as highly active photocatalysts for various reactions, including water splitting, − CO 2 reduction, − hydrogen peroxide synthesis, − and organic transformation reactions. − Their high activity compared to that of traditional CNs ,− is due to better light-harvesting properties, high specific surface area, suppressed recombination under illumination, and better charge mobility. , The synthesis of CNs with high crystallinity is typically achieved using molten salts as the reaction medium . The final composition and structure are usually determined by how the salt ions are stabilized at the high temperatures where the CN formation reaction takes place.…”