Nitrogen-Doped Reduced Graphene Oxide Covalently Coupled with Graphitic Carbon Nitride/Sulfur-Doped Graphitic Carbon Nitride Heterojunction Nanocatalysts for Photoreduction and Degradation of 4-Nitrophenol

Abstract

4-Nitrophenol (4-NP) is a high-priority industrial pollutant and is known to cause adverse effects to the human body. Owing to this, detoxification of water contaminated with 4-NP is highly essential. The photocatalytic degradation of 4-NP is considered an efficient method. However, for this purpose, mostly expensive reagents that can cause adverse effects on the environment are used. Therefore, for the treatment of 4-NP contaminated water, an eco-friendly method is considerably required. To meet this requirement, here, we have synthesized nitrogen-doped reduced graphene oxide (NrGO) covalently coupled with carbon modified porous graphitic carbon nitride/ sulfur-doped graphitic carbon nitride (g-C 3 N 4 /Sg-C 3 N 4 ) isotype heterojunction (g−g PSCN) nanocatalysts. The photocatalytic performance of the prepared NrGO/g−g PSCN nanocatalysts has been examined by the reductant-free reduction and H 2 O 2 -assisted degradation of 4-NP. The results of the photocatalytic performance suggest that the catalytic activity is strongly influenced by the presence of the NrGO content. For the 4NrGO/g−g PSCN nanocatalyst, the highest catalytic activity is observed, which is 12.25 and 2.92 times higher than that of g−g PSCN toward the reduction and degradation of 4-NP, respectively. The influence of various environmental factors such as solution pH, temperature, and the presence of competitive ions on the degradation rate of 4-NP have also been investigated. The reactive species involved during the reactions have also been explored, and a plausible mechanism has been proposed for both reactions. The durability and stability of the nanocatalysts have been examined, and the obtained results reveal that the nanocatalysts can endure the experimental conditions even after eight successive cycles. This approach opens up an avenue for the fabrication of graphitic carbon nitrite-based metal-free heterogeneous nanocatalysts with high catalytic performance.

Boosting Photocatalytic Activity Using Carbon Nitride Based 2D/2D van der Waals Heterojunctions

“…Additionally, the quantum confinement effect, up-conversion, and bright photoluminescence of quantum dots are appealing to harvest a major fraction of light. Indeed, extremely high numbers of reports are available on the use of carbon-based materials coupling with inorganic semiconductors to make 0D/2D, 0D/3D, 2D/2D, 2D/3D, and 3D/3D hybrids to improve photocatalytic properties. − Among them, 2D sheets of graphene and graphene oxide have proven to be the most promising due to their 2D nature and excellent optoelectronic properties. − Sticking to the scope of this review, we will revisit the scope of 2D carbon-based materials to integrate with g-C 3 N 4 based semiconductors.…”

A well-defined S-g-C3N4/Cu–NiS heterojunction interface towards enhanced spatial charge separation with excellent photocatalytic ability: synergetic effect, kinetics, antibacterial activity, and mechanism insights

“…25 Non-metallic element decoration (O, halogen elements, S, B, and P) is one of the viable solutions, as it may change the electrical properties and enhance the visible light-harvesting potential while still maintaining charge transference. [26][27][28] For example, Liu fabricated Sengineered g-C 3 N 4 by reacting g-C 3 N 4 with H 2 S as a S source at 449 C, which demonstrated signicantly higher photocatalytic H 2 evaluation ability than undoped g-C 3 N 4 . 29 Hong et al described that mesoporous SCN showed thirty times greater H 2 generation activity than pure g-C 3 N 4 .…”

Hematite nanoparticles decorated nitrogen-doped reduced graphene oxide/graphitic carbon nitride multifunctional heterostructure photocatalyst towards environmental applications

“…According to the previous reports, in this method, a nonfluorescent TA solution interacts with the photogenerated OH˙ radical to form fluorescent 2-hydroxyterephthalic acid (TAOH), which was detected by the PL technique. 48 Here, the fluorescence intensity of TAOH can be related to the OH˙ radical generation in the photoreaction. As shown in Fig.…”

“…For reference, rGO, g-C 3 N 4 , and α-Fe 2 O 3 were also prepared by following the aforementioned process without adding “urea and amorphous iron oxide,” “GO and amorphous iron oxide,” and “GO and urea.” NrGO was prepared by taking GO and urea as a nitrogen source using the thermal annealing process. 48 Scheme 1 depicts a schematic representation of the synthesis procedure for NGCF hybrid nanocomposites.…”

“…A modified Hummers' method was used to make graphene oxide (GO) from graphite powder, as reported by our research group. 47,48 In detail, in a round bottom flask, 2 g of graphite powder and NaNO 3 were dispersed in 50 mL of H 2 SO 4 under continual stirring for 2 h at 0 1C in an ice bath. Then, at room temperature, 6 g of KMnO 4 was gently introduced to the aforementioned suspension and agitated for 2 h, leading to the appearance of a brown colored slurry.…”