Search

The increasing demand for searching highly efficient and robust technologies in the context of sustainable energy production totally rely onto the cost‐effective energy efficient production technologies. Solar power technology in this regard will perceived to be extensively employed in a variety of ways in the future ahead, in terms of the combustion of petroleum‐based pollutants, CO2 reduction, heterogeneous photocatalysis, as well as the formation of unlimited and sustainable hydrogen gas production. Semiconductor‐based photocatalysis is regarded as potentially sustainable solution in this context. g‐C3N4 is classified as non‐metallic semiconductor to overcome this energy demand and enviromental challenges, because of its superior electronic configuration, which has a median band energy of around 2.7 eV, strong photocatalytic stability, and higher light performance. The photocatalytic performance of g‐C3N4 is perceived to be inadequate, owing to its small surface area along with high rate of charge recombination. However, various synthetic strategies were applied in order to incorporate g‐C3N4 with different guest materials to increase photocatalytic performance. After these fabrication approaches, the photocatalytic activity was enhanced owing to generation of photoinduced electrons and holes, by improving light absorption ability, and boosting surface area, which provides more space for photocatalytic reaction. In this review, various metals, non‐metals, metals oxide, sulfides, and ferrites have been integrated with g‐C3N4 to form mono, bimetallic, heterojunction, Z‐scheme, and S‐scheme‐based materials for boosting performance. Also, different varieties of g‐C3N4 were utilized for different aspects of photocatalytic application i. e., water reduction, water oxidation, CO2 reduction, and photodegradation of dye pollutants, etc. As a consequence, we have assembled a summary of the latest g‐C3N4 based materials, their uses in solar energy adaption, and proper management of the environment. This research will further well explain the detail of the mechanism of all these photocatalytic processes for the next steps, as well as the age number of new insights in order to overcome the current challenges. [ABSTRACT FROM AUTHOR]

Summary: Conjugated monomer 2,6‐dimethylindole (DMI) was integrated into the triazine framework of polymeric carbon nitride (PCN) via molecular engineering. As‐prepared samples were utilized for photocatalytic evolution of hydrogen (H2) through water splitting and photodegradation of RhB dye under visible light. The integration of this monomer DMI has been dominated within the internal framework of PCN and operated as a substitution reaction membrane, retarding an appropriate control and promote the charge density in π‐electron conjugated system. It also promotes the charge transferring and separation to elevate the photocatalytic activity of PCN under visible light. The HER for pure PCN was found as 77.9 μmol/h, while for PCN‐DMI18.0 was predicted at 701.2 μmol/h, which is exclusively output approximately nine times higher than that of pure PCN respectively. Besides, the pseudo‐order kinetic constant of PCN‐DMI18.0 degradation of RhB was multiple times higher when contrasted to pristine PCN. [ABSTRACT FROM AUTHOR]

Light-driven heterogeneous photocatalysis has gained great significance for generating solar fuel; the challenging charge separation process and sluggish surface catalytic reactions significantly restrict the progress of solar energy conversion using a semiconductor photocatalyst. Herein, we propose a novel and feasible strategy to incorporate dihydroxy benzene (DHB) as a conjugated monomer within the framework of urea containing CN (CNU-DHBx) to tune the electronic conductivity and charge separation due to the aromaticity of the benzene ring, which acts as an electron-donating species. Systematic characterizations such as SPV, PL, XPS, DRS, and TRPL demonstrated that the incorporation of the DHB monomer greatly enhanced the photocatalytic CO2 reduction of CN due to the enhanced charge separation and modulation of the ionic mobility. The significantly enhanced photocatalytic activity of CNU–DHB15.0 in comparison with parental CN was 85 µmol/h for CO and 19.92 µmol/h of the H2 source. It can be attributed to the electron–hole pair separation and enhance the optical adsorption due to the presence of DHB. Furthermore, this remarkable modification affected the chemical composition, bandgap, and surface area, encouraging the controlled detachment of light-produced photons and making it the ideal choice for CO2 photoreduction. Our research findings potentially offer a solution for tuning complex charge separation and catalytic reactions in photocatalysis that could practically lead to the generation of artificial photocatalysts for efficient solar energy into chemical energy conversion. [ABSTRACT FROM AUTHOR]

Proposed mechanism of BiVO 4 /CN-QA. [Display omitted] • Quinolinic acid (QA) doped g-CN (CN-QA) was developed via facile thermal approach. • Different samples of BiVO 4 /CN-QA with high stability were prepared via hydrothermal method. • Remarkable enhanced photocatalytic H 2 and O 2 evolution was achieved using these catalysts via overall water splitting. • A dual synergetic mechanism on BiVO 4 /CN-QA has been proposed. The development of copolymerized carbon nitride (CN)-based photocatalysts may support advances in photocatalytic overall water splitting. However, the recombination of charge carriers is the main bottleneck that reduces its overall photocatalytic activity. To overcome this problem, the construction of heterojunction technology has emerged as an effective approach to reduce the charge carrier recombination, thereby improving charge separation and transport efficiency. In this work, an innovative heterojunction was prepared between Quinolinic acid (QA) modified CN (CN-QA x) and novel nanorod-shaped bismuth vanadate (BiVO 4) (BiVO 4 /CN-QA x) for overall water splitting through a simple in-situ solvent evaporation technique. The obtained results show that the synthesized samples have efficient and improved activities for releasing H 2 (862.1 μmol/h) and O 2 (31.58 μmol/h) under visible light irradiation. Furthermore, an exceptional apparent quantum yield (AQY) of 64.52 % has been recorded for BiVO 4 /CN-QA 7.0 at 420 nm, which might be due to the substantial isolation of photoinduced charge carriers. Therefore, this work opens up a new channel toward efficient CN-based photocatalysts in the sustainable energy production processes. [ABSTRACT FROM AUTHOR]

Photocatalytic mechanism proposed for PCN-BTD 008 copolymer sample for overall water splitting under the illumination. [Display omitted] • BTD integrated copolymer (PCN-BTD) via thermal process. • An incorporation of BTD is reinforced by DFT data. • Eight-time enhanced HER of PCN-BTD 008 (744.2 μmol/h) than pure PCN (88.2 μmol/h). • The OER, generates 0.2 μmol/h−1 and 1.6 μmol/h−1 for PCN, while PCN-BTD 008 yield 2.2 μmol/h−1 (visible) and 14.8 μmol/h−1 (non-visible) respectively. Well-organized water splitting semiconducting photocatalyst is an important concept, but stimulating aimed at decisive energy and environmental emergencies. In this context, visible light-based photocatalytic water splitting with low-dimensional semiconducting materials is proposed to produce sustainable energy. Here we optimized the sequential of organic electron-rich heterocyclic monomer namely benzothiadiazole (BTD) quenched within polymeric carbon nitride (PCN) semiconductor via copolymerization, thereby assembling a sanctum of donor-π-acceptor (D-π-A) photocatalysts. The selection of BTD is based on the benzene ring, which consequently anticipating a π cross-linker unit for hydrogen and oxygen evolution. A hydrogen evolution rates (HER) of 88.2 μmol/h for pristine PCN and 744.2 μmol/h for PCN-BTD 008 (eight times higher than pure PCN) are observed. Additionally, a remarkable apparent quantum yield (AQY) of about 58.6% at 420 nm has been observed for PCN-BTD 008. Likewise, the oxygen evolution rate (OER) data reflect the generation of 0.2 μmol/h1 (visible) and 1.6 μmol/h1 (non-visible) for pure PCN. Though, OER of PCN-BTD 008 is found to be 2.2 μmol/h1 (visible) and 14.8 μmol/h1 (non-visible), which are economically better than pure PCN. As such, the results show an important step toward modifying the design and explain a vital part of the D-π-A scheme at a balanced theme for fruitful photocatalysts intended for future demand. [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]

Due to the future uses of solar energy in different areas, such as the oxidation of fossil fuel-based contaminants, the reduction of carbon dioxide, heterogeneous photocatalysis, and the generation of inexhaustible and renewable hydrogen gas exploits semiconductors. As a metal free photocatalyst, graphitic carbon nitride (g-C 3 N 4) is classified to solve these energy hazards and ecological difficulties owing to its excellent electronic structure with band energy of about 2.7 eV, robust photochemical stability, and better light-harvesting efficiency. However, its photocatalytic performance is still insufficient due to a minor surface area and poor conductivity. Therefore, heterojunction formation by combining it with a giant band gap material is a potential approach to reestablish polarization in its distinctive band structure, increase its light absorption capacity and enhance its surface area. In this regard, various synthesis techniques have been applied so far to integrate g-C 3 N 4 and other materials for boosting its photocatalytic activity. So far, metal oxide, sulfides, and ferrites are three crucial groups of materials that have been identified and defined to be used to synthesize g-C 3 N 4 dependent nanocomposites. As a result, in this review, we have compiled a list of the most recent g-C 3 N 4 nanocomposites with their applications in solar energy adaptation and pollution control. This study concludes an overview about the next steps to study the nanomaterials based g-C 3 N 4 composites and a range of additional insights to solve the present problems. • This review addresses the properties and structures of g-C 3 N 4 photocatalyst structure. • Pros and cons of their synthesis techniques. • The types of the g-C 3 N 4 -based nanocomposite are emphasized. • Approaches to improve the photocatalytic activity of g-C 3 N 4. • The most up-to-date photocatalytic applications were thoroughly discussed. [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]