Removing unreacted amino groups in graphitic carbon nitride through residual heating to improve the photocatalytic performance

Abstract

Calcination through residual heating could rapidly prepare g-C3N4 with fewer unreacted amino groups and higher crystallinity, which had a better photocatalytic performance than pristine g-C3N4.

Two Ways to more NH2-Groups: Formation of Polymeric Carbon Nitride via Melem Tetramer Nano Sheets or Supramolecular Assembly of Melamine and Cyanuric Acid for Applications as Photocatalyst

“…This is in good agreement with the surface areas of 4−24 m 2 g −1 observed by Nimbalkar et al for PCN that was prepared from melamine at 500−600 °C. 40 It is also known, that an increased synthesis temperature of PCN leads to less amino groups 41 as well as exfoliated sheets or particles, 42 which results in an increased surface area. The loss of NH 2 -groups at the boundaries of the particles could also lead to slit-shaped pores, which trigger the exfoliation.…”

A facile tert-butyl nitrite-assisted preparation of deamino graphitic carbon nitride (DA-gCN) as a photocatalyst for the C-H arylation of heteroarenes using anilines as radical source

“… a) An overview of methods used to synthesize deamino graphitic carbon nitride (DA-gCN) from pristine g-CN in the literature [ 9 – 11 ] and this study, and b) the radical C-H arylation of heteroarenes with anilines catalysed by DA-gCN-5 prepared by our method on TBN-assisted deamination. …”

“…Unlike metal-containing photocatalysts, which require high-cost precursors to be synthesized, g-CN may be made quickly by condensing inexpensive reactants like melamine, dicyandiamide, guanidine, and urea [ 4 – 7 ]. Despite these benefits, the presence of a substantial number of noncondensed amino groups in pristine g-CN severely restricts its usefulness as an efficient photocatalyst [ 8 – 9 ]. These amino groups operate as structural defects that trap photogenerated charges, which results in low photocatalytic activity [ 8 – 9 ].…”

“…Despite these benefits, the presence of a substantial number of noncondensed amino groups in pristine g-CN severely restricts its usefulness as an efficient photocatalyst [ 8 – 9 ]. These amino groups operate as structural defects that trap photogenerated charges, which results in low photocatalytic activity [ 8 – 9 ]. The postsynthetic calcination process around 650 °C is normally used to remove noncondensed amino groups in pristine g-CN ( Scheme 1a ).…”

“…For example, Dai and coworkers synthesized the deamino graphitic carbon nitride via postheating of the g-CN at 630 °C and described its application for the selective photosynthesis of azo- and azoxy-aromatics [ 10 ]. Very recently, Zhang and coworkers used the residual heating method to remove the amino-groups in the pristine g-CN and described the photocatalytic performance of calcinated (650 °C) g-CN for rhodamine B degradation, which was up to 7.8 times higher than that of pristine g-CN [ 9 ]. Using the catalytic application of deamino graphitic carbon nitride, which is created by postheating the g-CN at 630 °C, our lab has recently demonstrated the successful synthesis of a few organic molecules that will not form in the presence of pristine g-CN as a catalyst [ 11 ].…”