Regulating Polymerization in Graphitic Carbon Nitride To Improve Photocatalytic Activity

Abstract

Polymeric graphitic carbon nitride (g-CN) has emerged as a promising metal-free photocatalyst; however, the polymerization process is still poorly understood, and the synthesized g-CN shows a structural complexity, with photocatalytic activities far from being optimized. Herein we present new insight into its polymerization reaction kinetics and develop a quasi-sealed condensation route to properly regulate the distribution of the degree of polymerization (DP) in the synthesized g-CN. The correlation throughout the condensation process, the structure−property relationship, and the photocatalytic performance of g-CN have been discussed in detail. The synthesized g-CN shows a narrower and uniform DP distribution, possesses improved crystallinity, and features a nanoporous texture with fruitful amine groups and better water dispersibility, which promotes the fast chargecarrier transport under aqueous conditions and give rise to substantially enhanced photocatalytic activity. Compared with the conventional counterpart, its visible-light activity is 4.88 times higher for hydrogen production, 7.81 times higher for the degradation of rhodamine B, and 2.47 times higher for the degradation of 4-chlorophenol. We further report that its solar-driven photocatalytic activity is superior to that of the representative Degussa TiO 2 P25 catalyst for scale-up RhB degradation, thus highlighting the great prospects of g-CN-based photocatalysts toward practical applications.

Hydroxyl-group-modified polymeric carbon nitride with the highly selective hydrogenation of nitrobenzene to N-phenylhydroxylamine under visible light

“…2b) were in agreement with the decrease of the polymerization degree due to the etching of water molecules. 54 The electrochemical Mott-Schottky curves (Fig. S5) indicated n-type semiconductor structure for all samples, and provided Please do not adjust margins Please do not adjust margins S1), which was more negative than the reversible potential of PhNO 2 /[PhNO 2 ] • − (−0.8V vs. NHE).…”

Coupling TiO2 nanorods with g‐CN using modified physical vapor deposition for efficient photoelectrochemical water oxidation

“…For the pristine TiO 2 , the spectrum has a strong emission peak around 480 nm. The intensity of this peak quench remarkably after deposition g‐CN, indicating accelerate the separation of photogenerated carriers 18,36,37 …”

“…The intensity of this peak quench remarkably after deposition g-CN, indicating accelerate the separation of photogenerated carriers. 18,36,37 An amperometric I-T(relationship between current and time) of TiO 2 @g-CN5 NRs was performed under 100 mW/ cm 2 illumination at 1.23 V vs RHE to study the stability of the photoanode. As can be seen from Figure 10, the photocurrent density of TiO 2 @g-CN5 NRs anode remained stable in 10 hours.…”

Tailoring the stoichiometry of C3N4 nanosheets under electron beam irradiation

“…38 This is also observed with hexagonal boron nitride (h-BN), where B is preferentially removed over N from the graphene-like lattice. [39][40][41] Moreover, since the C : N ratio (stoichiometry) may play an important role in the nature of the g-C 3 N 4 lattice, and given that N appears to be ejected preferentially, we decided to investigate the loss of N in further detail. EELS data were collected for acceleration voltages of 300, 80, and 60 kV, as shown in Fig.…”

“…As mentioned in the introduction, g-C 3 N 4 can be obtained with various degrees of polymerization [41][42][43] depending on the precursor materials and synthetic conditions, which play a crucial role in the polymerization of the final product and its subsequent properties. 44 Our data show that under electron irradiation, there is a clear increase in the C : N ratio. The difference between the measured C : N 34 changes significantly with the selected electron acceleration voltage, as shown in Fig.…”