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One of the most frequent ways to widen the adsorption range of carbon nitride (CN) is to add a well-known photosensitizer into its basic structure. So far, such attachments have been accomplished by using weak van der Waals forces. However, using strong covalent bonding to attach such photosensitizer with CN is yet to be determined. Here, for the first time, we covalently bonded porphyrin (5,10,15,20-tetrakis(4-(2,4-diamino-1,3,5-triazinyl) phenyl)-Porphyrin (TDP)), a renowned photosensitizer, effectively with CN by thermally balanced molecular strategy. A photoreaction system was set up for the deoxygenated conversion of CO2 to CO under visible light, where cobalt acted as a redox controller to speed up the charge transportation, while CN-TDP worked as a CO2 activating photocatalyst. The subsequent photocatalyst has a broader absorbance range, a greater specific surface area, and intramolecular organic connections that help to decrease the electron-hole pairs' recombination rate. Furthermore, the average weight ratio between urea and TDP was well-tuned, resulting in a fantastic CO2 photoconversion for CN-TDP7.0 compared to the blank sample. This substantial increase in photocatalytic activity predicts a significant shift in CN's specific surface area, band gap, chemical composition, and structure, as well as the efficient separation of photogenerated charge carriers from the ground state (HOMO) to the excited state (LUMO), making it a top candidate for CO2 photoreduction. At the same time, this approach paves the path for the bottom-up fabrication of carbon nitride nanosheets. [ABSTRACT FROM AUTHOR]

Recently, the graphite based heterogeneous photocatalysts has attained tremendous research attention in various environmental applications. Among them, the graphitic carbon nitride (g-C 3 N 4) is categorized as a unique solar active particle with its outstanding intrinsic properties i.e., adequate band configuration, excellent light absorptivity and thermo-physical durability, which make it highly useful and reliable for revenue transformation and ecological concerns. Considering the intrinsic potential of g-C 3 N 4 in photocatalysis, so far, no report has been done in literature for its extraordinary configuration, morphological characteristics and perspective tuning for said applications. To overcome this research gap, our primary emphasis of this review regarding photocatalysis is to provide layout as well as the advancement of visible-light-fueled materials as highly stabilized and extremely effective ones for pragmatic implementation. Thus, this existing comprehensive assessment conducts a systematic survey over visible light driven non-metal novel g-C 3 N 4. The major advancement of this evaluation is the fabrication of well-designed nanosized g-C 3 N 4 photocatalysts with unique configurable frameworks and compositions. Furthermore, alternative techniques in order to customize the analogue band configuration and noticeable cultivation such as metal (cation), nonmetal (anion) doping, worthy metal activating, and alloy initiation with certain semiconductors are discussed in detail. In addition to this, g-C 3 N 4 photocatalytic functionalities towards photocatalytic hydrogen evolution, CO 2 photoreduction, biological metal ions deterioration as well as bacterial sanitization are also presented and discussed in detail. Therefore, we believe that such a pivotal compact assessment can provide a roadmap in several perspectives on the currently underway obstacles in the innovation of effective g-C 3 N 4 catalytic design processes. Moreover, this critical assessment will ultimately serve as a useful supplement in the research area of g-C 3 N 4 nanosized photocatalysts and for the researchers working on its key aspects in diverse range of natural, chemistry, engineering and environmental applications. • Graphitic carbon nitride (g-C 3 N 4) is a metal-free sustainable photocatalyst with a band gap of 2.7 eV. • G-C 3 N 4 has improved light absorption performance as well as electronic features. • Multiple synthetic approaches are being used with g-C 3 N 4 to improve its photocatalytic capabilities. • Metals/nonmetals doping, activation, and alloy formation are employed for g-C 3 N 4 nanocomposites. • Our review includes the latest current g-C 3 N 4 nanocomposites and their photocatalytic implications. [ABSTRACT FROM AUTHOR]

• A carbon abundant 2‐D structure material 5,8-dibromoisoquinoline (BQ) has been integrated as an aromatic organic monomer within carbon nitride (CN) via molecular aggregation process. • The BQ copolymerized CN with distinguish characteristics leads to a significant increment in the applied application. • The copolymerized samples demonstrating narrowed band gap, high surface area, splendid morphology, and wide optical absorbance which enhanced electron transport ability. • The spinal material, i.e., 10BQ/CN exhibited a superior H 2 evolution of ten‐fold higher activity and also photodegradation of RhB under visible light driven. Graphitic carbon nitride, g-C 3 N 4 (CN) is regarded as an excellent metal-free semiconductor known for its potential solar fuel generation and pollutant degradation. In this study, a carbon richer substance, (5,8-dibromoisoquinoline (BQ)) was used to feed its catalytic function through conventional copolymerization (molecular doping) process at 550°C under a nitrogen atmosphere. The incorporation of BQ monomer in the triazine oligomers of CN in turn enhanced the specific surface area, thereby, improving the lifespan of photoexcited charge carriers, decreasing the charge recombination rate, energy bandgap, and altering the optoelectronic characteristics of CN. On average, the rate of hydrogen (H 2) production over-optimized 10BQ/CN was 710.1 µmol/h much superior and 10 times higher than that of pure CN (71.9 µmol/h). Particularly, the kinetics of the photocatalytic degradation of RhB over 10BQ/CN followed pseudo-order kinetics and the rate constant was three times larger than pure CN. Our results illustrate the crucial importance of conjugated monomers in improving photocatalysis process for future energy demand by providing key steps towards sustainable energy production. [Display omitted]. [ABSTRACT FROM AUTHOR]

• Molecular engineering (copolymerization) strategies has been utilized by modulating aromatic heterocyclic monomer Uric Acid (UA) within carbon nitride (CN) copolymer (CN/UA). • Incorporation of Uric acid (UA) alter a significant fluctuation in the surface area, electronic structure, band gap, chemical composition of CN and boosting the process of photogenerated electrons/holes. • The modified samples demonstrating a momentous enhancement in the photocatalytic performance of water reduction (H 2 evolution) and pollutants degradation (RhB). • This novel integrity of UA co-monomer with in CN matrix remarkably improve the photocatalytic activity toward prosperity and as such the best photocatalyst CN/UA 10.0 accelerate an outstanding photocatalytic activity of water reduction as 8 times higher compared of pure CN respectively. An ideal solution to water or pollutant contamination and energy problem is to advance photocatalysts that are highly effective for both reducing contaminants and cleaning water. In this regard, carbon nitride (CN) has strong stability with prominent band structure and can be used to produce hydrogen through water splitting due to an easier fabrication process. Uric acid (UA) was integrated as a conjugated monomer in the urea based CN system using the molecular doping (copolymerization) process. The photocatalysis of water reduction (HER) by using a new growth technique of minimally priced effective monomer UA inside CN, which also optimized the photodegradation of Rhodamine B dye (RhB) under light illumination (λ = 420 nm). By increasing light transmittance, speeding up photogenerated electrons and holes, and changing the physicochemical properties of CN, modified samples dramatically improve photocatalytic efficiency. The ideal samples CNU-UA 10.0 showed a substantial increase in photocatalytic activity, with an HER 690.01 μmol/h higher than CNU (82.89 μmol/h), based on the implications of different configurations on the reaction mechanism. Moreover, an extraordinary apparent quantum yield (AQY) of about 57.43% at 420 nm has been observed for CNU-UA 10.0. Under the same conditions and illuminations, H 2 performance versus RhB dye degradation was compared. CNU-UA, on the other hand, had a three-fold higher pseudo-order kinetic constant for photodegradation of RhB than CN. The results demonstrate a major step toward in the direction of custom-designed photocatalysts with efficient water reduction and pollutants degradation capability for future demand. [ABSTRACT FROM AUTHOR]