Construction Of g-C3N4 Research Articles

Construction of g-C3N4/BiOCl hybrids via hydrothermal synthesis for efficient photocatalytic degradation of Tetracycline, Rhodamine B, and Nitenpyram

A photocatalysis system is widely regarded as the most renewable approach to environmental treatment since sunlight is a long-term source of energy for the planet. This study assessed the efficacy of a photocatalyst graphitic carbon nitride/bismuth oxychloride (g-C3N4/BiOCl) by using scanning electron microscopy (SEM), ultraviolet-visible diffuse reflectance spectroscopy (DRS), photo-luminance, photocurrent density, and X-ray diffraction to characterize the photocatalyst. The results showed an improvement in morphology and enhanced photodegradation of pharmaceutical residues such as Nitenpyram, Tetracycline, and Rhodamine B. For a wavelength range of 655 to 420 nm, the synthesized photocatalysts were good at the absorption of visible light. A photodegradation proficiency of 64.72% was observed with tetracycline, 48.91% nitenpyram, and 98.70% with Rhodamine B in 30 min. The g-C3N4/BiOCl displayed a significant photocatalytic activity due to high load separation and transition. This study shows that g-C3N4/BiOCl photocatalyst has been confirmed as one of the most intriguing contenders for innovative photocatalyst designs and can potentially be used in treating wastewater and the environment at large.

Fabrication and improved photocatalytic performance of 2D/0D structured g-C3N4/WO3 composite materials

In this work, WO3 quantum dots grow in situ on the synthesized ultra-thin g-C3N4 nanosheets, ultimately forming a type of tightly bound 2D/0D Z-type heterojunctions. It was found that WO3 quantum dots were closely combined with g-C3N4 nanosheets through SEM and TEM measurements. XRD, IR, and XPS characterization proved a g-C3N4/WO3 heterojunction material was formed. The construction of g-C3N4/WO3 heterojunctions enhanced visible light absorption, improved carrier separation efficiency, and reduced charge transfer resistance. Photocatalytic hydrogen production tests showed that the hydrogen production rate of 20% g-C3N4/WO3 composite materials was 2.8 times that of the original g-C3N4, and the hydrogen production amount within 3 h was 3.7 times that of the original g-C3N4. Photocatalytic degradation of Rhodamine B and 4-chlorophenol under visible light irradiation showed that compared with g-C3N4, the photocatalytic degradation efficiency of 20% g-C3N4/WO3 composite materials was enhanced. The results reveal that the special structured g-C3N4/WO3 composite materials have excellent photocatalytic activity, which can not only efficiently produce hydrogen but also efficiently degrade organic pollutants, providing an important reference for solving energy crises and environmental problems.

Efficient removal of TC and CIP antibiotics by surface modified g-C3N4/CdS nanocomposite under sunlight irradiation

Aquatic environment organic pollutant removal is very essential for human health. Tetracycline (TC) and Ciprofloxacin (CIP) are most use antibiotics to treat the bacterial infections. These antibiotics are entering into the aquatic system through feces and urine of both humans and animals, thereby increasing the environmental toxicity. Consequently, it is crucial to treat the antibiotics residues from the aquatic environment. Photocatalysis method is considered as a promising way to effectively treat the contaminated aquatic environment. The g-C3N4/CdS was successfully synthesized through a simple hydrothermal method. Various characterization techniques were used to examine the physical and chemical characteristics of the synthesized materials. The g-C3N4/CdS nanocomposite has high surface area 76.12 m2/g, narrow band gap energy 2.26 eV, and less electron-hole recombination. The g-C3N4/CdS photocatalyst shows higher degradation efficiency of TC and CIP as 96.2 and 80% in 40 min under sunlight irradiation. In addition, the radical trapping experiment reveals that h+, •O2− and 1O2 are the key role for the degradation of TC and CIP over g-C3N4/CdS nanocomposite. Moreover, the intermediate by products of TC and CIP were also examined by using GC-MS. This work, facilitates that the construction of g-C3N4/CdS nanocomposite have high capable to remove the toxic substances from the contaminated water under direct sunlight irradiation.

Construction of g-C3N4/Fe-MOFs Type-Ⅱ heterojunction promotes photo-Fenton degradation of doxycycline

A type-II heterojunction photo-Fenton catalyst g-C3N4/Fe-MOFs was synthesized with the utilization of waste PET by dielectric barrier discharge (DBD) plasma. The coupling of Fe-MOFs enhanced the visible-light absorption regions of g-C3N4, and induced the formation of type-II heterojunction, which inhibited the recombination of photo-generated electrons and holes. g-C3N4/Fe-MOFs exhibited a much higher photo-Fenton catalytic performance, which was 4.42 and 3.30 times higher than that of g-C3N4 and Fe-MOFs for the degradation of doxycycline (DOX), respectively. The enhanced photo-Fenton catalytic performance could be attributed to the synergistic electron transfer interface between g-C3N4 and Fe-MOFs, thus inhibiting the recombination of photo-generated electrons and holes. The possible mechanism of photo-Fenton degradation of DOX with g-C3N4/Fe-MOFs was proposed based on the radical trapping experiments, as well as the characterization of EPR and Mott-Schottky. This research could provide an efficient and green method for the utilization of waste PET and the treatment of antibiotic wastewater.

Construction of g-C3N4 with N2C-type defects/MoO3 Z-scheme photocatalyst: Effective mineralization and toxicity reduction of microcystin-LR by multiple free radical degradation pathways

Algal blooms have resulted in the buildup of microcystin (MC-LR) in water bodies, posing a severe hazard to the safety of the aquatic ecosystem and human health. This study produced a g-C3N4 with N2C-type defects/MoO3 Z-scheme photocatalyst (D-CN/MoO3) for MC-LR degradation in visible light. D-CN/MoO3 could photodegrade 100 % MC-LR within 25 min, which was substantially more significant than pure g-C3N4 (12.5%). Meanwhile, the kinetic constant was 32.5 times higher than pure g-C3N4, attributed to the defect engineering and Z-scheme heterojunction cooperative interaction. Based on the LC-MS results, the vital degradation mechanism is the selective assault of 1O2 on the Adda side chain of MC-LR and the following decarboxylation reaction of h+, which leads to effective mineralization and reduced toxicity of MC-LR. Moreover, the excellent stability and adaptability of D-CN/MoO3 are verified and have a significant potential for application in the decontamination of MC-LR in eutrophic water.

The construction of a heterostructured RGO/g-C3N4/LaCO3OH composite with enhanced visible light photocatalytic activity for MO degradation.

The construction of a heterojunction and the introduction of a cocatalyst can both promote the transfer of photogenerated electrons, which are effective strategies to enhance photocatalytic efficiency. In this paper, a ternary RGO/g-C3N4/LaCO3OH composite was synthesized by constructing a g-C3N4/LaCO3OH heterojunction and introducing a non-noble metal cocatalyst RGO through hydrothermal reactions. TEM, XRD, XPS, UV-vis diffuse reflectance spectroscopy, photo-electrochemistry and PL tests were carried out to characterize the structures, morphologies and carrier separation efficiencies of products. Benefiting from the boosted visible light absorption capability, reduced charge transfer resistance and facilitated photogenerated carrier separation, the visible light photocatalytic activity of the ternary RGO/g-C3N4/LaCO3OH composite was effectively improved, resulting in a much increased MO (methyl orange) degradation rate of 0.0326 min-1 compared with LaCO3OH (0.0003 min-1) and g-C3N4 (0.0083 min-1). Moreover, by combining the results of the active species trapping experiment with the bandgap structure of each component, the mechanism of the MO photodegradation process was proposed.

Construction of g-C3N4/CdS/BiVO4 ternary nanocomposite with enhanced visible-light-driven photocatalytic activity toward methylene blue dye degradation in the aqueous phase

Herein, the ternary CdS/BiVO4/g-C3N4 (CBG) hybrid semiconductor photocatalyst was prepared via a hydrothermal technique. The synthesized photocatalysts were thoroughly characterized using powder XRD, XPS, FTIR, SEM, TEM, and UV-DRS to investigate the microstructural, morphological attributes, and optical properties. The photocatalytic activity of the ternary CBG hybrid semiconductor was assessed through the photodegradation of Methylene Blue (MB) aqueous dye under visible light. The outcomes exhibited that the CBG hybrid semiconductor showed excellent photocatalytic activity (about 94.5% after 120 min) compared to the results obtained with the pristine materials or the other composite (CdS/BiVO4). The enhancement of photocatalytic activity can be due to the construction of heterojunctions among g-C3N4, CdS, and BiVO4, which improves charge transfer efficiency and hence favors the degradation of organic dyes. Moreover, the as-prepared photocatalyst showed excellent stability after five cycles, indicating good stability and reusability. Subsequently, a possible photocatalytic mechanism was proposed based on the experimental results. The current investigation provides a promising strategy to promote photocatalytic activity to eliminate waterborne contaminants.

Construction of g-C3N4 with three coordinated nitrogen (N3C) vacancies for excellent photocatalytic activities of N2 fixation and H2O2 production

Nitrogen defect engineering has been confirmed to be an effective strategy to improve photocatalytic performance, and nitrogen vacancies at different positions show different effects on photocatalytic performance. Here, we prepare g-C3N4 with three-coordinate nitrogen (N3C) vacancies (g-C3N4-N3C) by a simple in situ copyrolysis method. The introduction of N3C vacancies helps to narrow the band gap, enhance the light-harvesting efficiency, accelerate the separation and transfer of photogenerated carriers, and provide more active centers. Interestingly, g-C3N4-N3C exhibits photocatalytic performance for the production of NH3 and H2O2. The optimized g-C3N4-N3C-0.3 exhibits the best photocatalytic N2 fixation rate (1915 μmol h−1 g−1) and photocatalytic H2O2 production rate (1098 μmol h−1 g−1), with corresponding apparent quantum efficiency (AQE) of 7.79 % and 12.43 % at λ = 370 nm, respectively, which are superior to most known photocatalysts. Meanwhile, density functional theory (DFT) calculations indicate that g-C3N4-N3C makes the activation and further reduction of *N2 and *O2 more thermodynamically favorable than pure g-C3N4. This work deepens the understanding of the role of nitrogen defect engineering in enhancing the photocatalytic performance of g-C3N4, and provides a new way for the design and preparation of efficient and stable photocatalysts.

Construction of g-C3N4/BiOCl/CdS heterostructure photocatalyst for complete removal of oxytetracycline antibiotic in wastewater

One of the vital topics in photocatalysis research is the development of novel photocatalytic nanomaterials for degradation of toxic pollutants in the natural water under visible light irradiation. Herein we report, for the first time, a facile hydrothermal synthesis of g-C3N4/BiOCl/CdS heterojunction for complete removal of oxytetracycline (OTC) antibiotic in wastewater. The suppression of electron-hole recombination rate was obtained after creation of the ternary heterostructure. Accordingly, the enhanced photoactivity was found in the prepared heterojunction photocatalyst as expected. Complete removal of OTC was obtained under natural sunlight irradiation. The removal of OTC follows the first-order reaction with the maximum rate constant of 0.023 min−1. The prepared photocatalyst still maintains its structural stability with high photocatalytic performance even after seven times of use. Photogenerated holes are the crucial species involved in the OTC removal while electrons and hydroxyl radicals play a subordinate role. Charge transfer at the interface of the ternary heterojunction is proposed to be the Z-scheme type. The present work shows a promising strategy to create a novel ternary heterojunction with an enhanced photoactivity for complete detoxification of harmful OTC antibiotic in the environment.

Construction of g-C3N4/Au/NH2-UiO-66 Z-scheme heterojunction for label-free photoelectrochemical recognition of D-penicillamine

The wide clinical application of d-penicillamine (D-PA) makes it inevitably accumulates in the environment, seriously threatening human health and the ecological environment. To better supervisory control D-PA, a highly sensitive and reliable photoelectrochemical (PEC) sensor based on gold nanoparticles (Au NPs) loaded on graphitic carbon nitride sheet and hexagonal NH2-UiO-66 composite (g-C3N4/Au/NH2-UiO-66) was synthesized. Tactfully using the strong bonding between D-PA and Au NPs and the effective carrier separation of Z-scheme heterojunction, the designed g-C3N4/Au/NH2-UiO-66 PEC sensor without an extra recognition unit exhibited a selective and sensitive photocurrent to D-PA. With the aid of UV diffuse reflectance spectra (UV-DRs), electron paramagnetic resonance (EPR) characterization, and free radical capture experiments, the electron transfer path of the PEC sensing system was deduced. The proposed g-C3N4/Au/NH2-UiO-66 PEC-based sensor achieved a low detection limit of 0.0046 μM (S/N = 3) with a wide linear response ranging from 10 nM to 400 μM. In addition, its good stability and selectivity also laid a good foundation for practical applications.

Construction of g-C3N4/Ag/TiO2 Z-scheme photocatalyst and Its improved photocatalytic U(VI) reduction application in water.

The reduction of soluble U(VI) to insoluble U(IV) by photocatalytic technology is considered to be a valid method to remove U(VI) from water. Herein, g-C3N4/Ag/TiO2 Z-scheme heterojunction was synthesized for photocatalytic U(VI) reduction application. The SEM, XRD and XPS characterization results showed that a ternary g-C3N4/Ag/TiO2 composite photocatalyst was synthesized successfully. g-C3N4/Ag/TiO2 exhibited excellent photocatalytic reduction performance for U(VI) under visible light irradiation. After 30 min irradiation, the removal rate of U(VI) was above 99%. XPS indicated that the majority of U(VI) on the surface of g-C3N4/Ag/TiO2 was reduced to U(IV). In addition, the photocatalytic activity of g-C3N4/Ag/TiO2 has been kept significantly after five rounds of experiments, indicating good stability. g-C3N4/Ag/TiO2 exhibited better photocatalytic reduction of U(VI) under visible light irradiation, which is mainly ascribed to Z-scheme photocatalytic mechanism assisted by the LSPR effect (Local Surface Plasmon Resonance). Ag with plasmon resonance effect on the loading has a strong absorption of photon energy. In addition, an intermediate charge transfer channel is formed between Ag and the semiconductor to inhibit the combination of photogenerated electrons and holes, resulting in a significant increase in the photocatalytic activity of the photocatalyst. This idea has some significance in design of other composite photocatalytic systems.

In situ forming heterointerface in g-C3N4/BiOBr photocatalyst for enhancing the photocatalytic activity

Removing wastewater with organic pollutants or medicine using semiconductor photocatalysts has attracted increasing attention in recent decades. However, low visible light utilization, high charge carrier recombination and insufficient surface active sites are still the limitation of photocatalysts. Herein, an in situ-forming BiOBr nanosheets on the surface of g-C3N4 were successfully synthesized via water bath in ambient temperature. The carboxyl group of acetic acid plays a vital role in growing for BiOBr nanosheets. The particular construction of g-C3N4/BiOBr composites increases the active sites and improve separation efficiency of photogenerated carriers, which strengthen photocatalytic degradation for pollutants. Meanwhile, electrons were transmitted quickly in the layered graphite carbon of g-C3N4 which owns excellent electrical conductivity. As a result, this work provides a novel approach to in-situ construction of semiconductor heterojunctions and demonstrates the prepared g-C3N4/BiOBr photocatalysts behave great potential in the removal of pollutants.

Visible-Light-Driven g-C3N4/TiO2 Based Heterojunction Nanocomposites for Photocatalytic Degradation of Organic Dyes in Wastewater: A Review

Water pollution by organic contaminants is one of the most severe issues confronting the world today as a result of the rapid increase of industrialization, urbanization, human population growth, and advances in agricultural technologies. Several attempts have been made to address global water pollution issues by utilizing conventional wastewater treatment technologies. However, conventional wastewater treatment methods have several limitations such as low efficiency, high operation costs, generation of secondary waste, require additional chemicals as oxidants and extra energy. Therefore, Heterogeneous photocatalysis has gained a lot of attention in the degradation of persistent organic pollutants because it combines high efficiency, environmental friendliness, cheap cost, and safety. Subsequently, the designing of novel nanocomposite photocatalysts with strong visible light-harvesting ability, efficient charge separation and transportation, and superb stability is imminently desired for wastewater treatment. Recently, the notion of combining g-C3N4 with TiO2 to design high photocatalytic performance heterojunction photoactive nanocomposites for organic pollutant degradation has received a lot of attention. Meanwhile, the construction of g-C3N4/TiO2-based heterojunction nanocomposites may enhance the ability of harvesting visible light, boost charge separation and transfer efficiency, and robust photocatalytic activity. Firstly, this review concisely explained the main sources of water pollution, as well as potential treatment approaches and the fundamental mechanism of heterogeneous photocatalysis. Subsequently, the details of properties, synthesis techniques, photoactivity modification strategies, and photocatalytic applications of g-C3N4, TiO2, and g-C3N4/TiO2 heterojunction photocatalysts are presented. Following that, the recent advances aimed at improving the photocatalytic performance of various types of visible-light-driven g-C3N4/TiO2 heterojunction photocatalysts for organic pollutant degradation in wastewater are presented in detail. Finally, some concluding remarks and perspectives on the challenges and opportunities for constructing different types of g-C3N4/TiO2-based heterostructured photocatalysts are presented.

Construction of g-C3N4 nanotube/Ag3PO4 S-scheme heterojunction for enhanced photocatalytic oxygen generation

Heterojunction engineering is considered as a hopeful approach to ameliorate the separation of photogenerated carriers of photocatalysts, realizing efficient water-splitting performance. In this study, an organic-inorganic S-scheme of a one-dimensional g-C3N4 nanotube (TCN)/Ag3PO4 photocatalytic system with high photocatalytic water oxidation activity was designed by coupling g-C3N4 nanotubes over Ag3PO4 particles through a chemical coprecipitation method. The TCN/Ag3PO4 heterojunction demonstrated excellent photocatalytic O2 production with an O2 evolution rate of up to 370.2 μmol·L−1·h−1. X-ray photoelectron spectroscopy analysis showed that electron migration between TCN and Ag3PO4 led to the formation of an internal electric field pointing from TCN to Ag3PO4, which drove the S-scheme charge transfer mode between TCN and Ag3PO4. Accordingly, the TCN/Ag3PO4 heterojunction possessed fast charge separation and high redox ability, leading to high photoactivity and photostability. This research provides a new strategy for fabricating highly efficient inorganic-organic S-scheme photocatalysts for O2 production.

In Situ Construction of G-C3n4/G-C3n4 Homotype Heterojunction for Enhanced Cyclic Stability of Li-S Batteries

In Situ Construction of G-C3n4/G-C3n4 Homotype Heterojunction for Enhanced Cyclic Stability of Li-S Batteries

Construction of g-C3N4/Bi4Ti3O12 hollow nanofibers with highly efficient visible-light-driven photocatalytic performance

The exploration and development of effective and persistent visible-light-responsive photocatalysts for environmental remediation is regarded as one of the most challenging current research areas. Herein, a novel g-C3N4/Bi4Ti3O12 (CN/BTO-X; X = 6, 9 and 10.8) hollow nanofiber composite was fabricated through a convenient electrospinning/calcination technique, followed by thermal polymerisation. The SEM and TEM images showed that CN/BTO composite mainly comprised a hollow nanofiber morphology with a diameter of 110 ± 20 nm. The XPS result confirmed the interfacial interaction between BTO and CN, implying the formation of a heterojunction between these components. Photocatalytic measurements revealed that the as-synthesized CN/BTO composite exhibited excellent and stable photocatalytic behaviour of dislodging multiple pollutants (including RhB, MO, TC and Cr (VI) etc.) with visible light (λ > 420 nm). Among these prepared composites, the CN/BTO-9 sample exhibited the highest photocatalytic performance with the rate constants of 0.03064 min−1 (TC), 0.11274 min–1 (RhB), 0.04474 min–1 (MO) and 0.01938 min–1 (Cr(VI)), respectively. The outstanding catalytic performance was ascribed to the high specific surface area, improved visible-light adsorption, heterostructure of CN/BTO with strong oxidative ability and efficient separation of photoinduced charge carriers, and its unique hollow nanofiber structure. The active species-capturing experiments and ESR tests verified that h+ and O2− were responsible for RhB/TC degradation. The mechanism accounting for the observed catalytic activities was discussed according to the band gap structure, DFT calculations and free radicals capture tests.

Construction of g-C3N4/Bi4O5I2 heterojunction via the solvothermal method for the purification of eutrophic water

Heterojunction photocatalysts of g-C3N4/Bi4O5I2 were designed through the solvothermal method. A series of characterizations were used to analyze the structure, morphology, and optical and electronic characteristics of g-C3N4/Bi4O5I2 composite. Bi4O5I2 was successfully dispersed on the surface of g-C3N4. The 3 wt%-g-C3N4/Bi4O5I2 catalyst had the highest photocatalytic activity in eutrophic water. The degradation efficiency of chemical oxygen demand (CODMn), total nitrogen (TN), and chlorophyll a (Chl-a) was as high as 90.1%, 60.2%, and 66.1%, respectively. Based on the band structure analysis, the purification can be attributed to the transfer and separation of holes (h+) and electrons (e−) between g-C3N4 and Bi4O5I2.

Construction of g-C3N4/TiO2 nanotube arrays Z-scheme heterojunction to improve visible light catalytic activity

A simple anodic oxidation method was used to prepare TiO2 nanotubes (TNTs), and calcined at 500 °C with urea to prepare g-C3N4/TNTs (CN/TNTs) composites. The photocatalytic activity of TNTs was improved by constructing a Z-scheme transfer mechanism. The results show that 2 g CN/TNTs greatly improves the separation efficiency of electron-hole pairs and reduces its recombination efficiency, and the visible light absorption also undergoes a significant redshift. The degradation of rhodamine B can reach 96.3 %, and the degradation rate is 0.0195min−1. The sample has good stability and can be used repeatedly without losing activity. In the CN/TNTs system, h+, O2- and OH are active species.

Construction of g-C3N4/WO3/MoS2 ternary nanocomposite with enhanced charge separation and collection for efficient wastewater treatment under visible light

Graphitic carbon nitride (g-C3N4) has enormous potentials for photocatalysis, yet it only possesses moderate activity because of excitonic effects and sluggish charge transfer. Here, we develop a novel two-dimensional g-C3N4/WO3/MoS2 (CWM) ternary nanocomposite through a facile co-calcination and a hydrothermal process to reach a highly-efficient photocatalyst for organic pollutant elimination under visible light. The WO3 and MoS2 nanoparticles were dispersed on the ultra-thin g-C3N4 nanosheets, in which the electronegative g-C3N4 facilitates formation of oxygen vacancies in WO3. Compared to pure g-C3N4, WO3, and binary composites, CWM exhibited higher photocatalytic activities for various organic pollutants removal under visible light irradiation. For instance, the CWM showed a removal ratio of ∼99% for RhB after only 10 min irradiation of visible light (λ > 420 nm) and nearly 100% for ciprofloxacin after 2 h of operation. The results showed that OH radicals are the main active species for organic degradation, which suggests a direct Z-scheme heterojunction in CWM that improved spatial separation of charge carries. Furthermore, the collection of electrons is significantly enhanced by MoS2 for oxygen reduction reaction, and the increased oxygen vacancies of WO3 further enhanced the separation of electron-hole pairs; therefore, it led to an effective suppression of charge carriers recombination. The above synergistic effects of ternary photocatalyst result in higher photocatalytic oxidation performance for wastewater treatment compared with pure WO3, g-C3N4 and their binary composites.

Construction of g-C3N4/TiO2/Ag composites with enhanced visible-light photocatalytic activity and antibacterial properties

In this study, the multifunctional carbon nitride based composite graphitic-C3N4 (g-C3N4)/TiO2/Ag was prepared through a simple and efficient vacuum freeze-drying route. TiO2 and Ag nanoparticles were demonstrated to decorate onto the surface of g-C3N4 sheet. In the ultraviolet–visible absorption test, a narrower band gap and red-shift of light absorption edge were observed for g-C3N4/TiO2/Ag compared to pristine g-C3N4 and single-component modified g-C3N4/TiO2. The photodegradation property of g-C3N4/TiO2/Ag was investigated toward the degradation of methylene blue (abbreviated as MB) under the irradiation of visible light. These results indicated that the degradation performance of organic dyes for g-C3N4/TiO2/Ag was obviously improved compared with g-C3N4/TiO2 and g-C3N4. The reaction rate constant of MB degradation for g-C3N4/TiO2/Ag was 4.24 times higher than that of pristine g-C3N4. In addition, such rationally constructed nanocomposite presented evidently enhanced antibacterial performance against the Gram-negative Escherichia coli. Concentration dependent antibacterial performance was systematically investigated. And 84% bacterial cell viability loss had been observed at 500 μg/mL g-C3N4/TiO2/Ag within 2 h visible light irradiation.