3N4 Composites Research Articles

Direct Z-scheme In2O3/g-C3N4 nanocomposites: Breaking through the performance limitations of conventional type II heterojunctions for photocathodic protection of Q235 CS in 3.5 wt% NaCl solution

Direct Z-scheme flaky In2O3/ rod-shaped g-C3N4 nanocomposites were successfully prepared by hydrothermal and spin coating methods, and the photocathodic protection performance for 304 SS and Q235 CS was studied in 3.5 wt% NaCl solution. It revealed that the In2O3/g-C3N4 heterojunctions significantly improves the photocathodic protection ability, compared with In2O3 and g-C3N4. The self-corrosion potentials of 304 SS and Q235 CS coupled with In2O3/g-C3N4 nanocomposites decreased by 450 mV and 350 mV after lighting, and the photoinduced current densities were 55 μA·cm−2 and 31 μA·cm−2, which are 11 and 17.2 times that of g-C3N4. In addition, the cathodic coupling current density of 304 SS coupled with In2O3/g-C3N4 increased from 2.62 μA·cm−2 to 17.79 μA·cm−2, and that of Q235 CS increased from 1.78 μA·cm−2 to 12.36 μA·cm−2. Moreover, the enhanced mechanism of In2O3/g-C3N4 heterojunctions was systematically discussed. The construction of flaky g-C3N4/ loaded on the rod-shaped nano-In2O3 resulted in faster electron migration and enhanced light absorption capability. Furthermore, XPS, ESR analysis and the deposition of PbO2 indicated that In2O3/g-C3N4 composites follow the Z-scheme electron migration path and retain the stronger redox ability of In2O3/g-C3N4. Therefore, the Z-scheme heterostructures are responsible for the realization of cathodic protection for carbon steel in 3.5 wt% NaCl solution.

Construction of rare-metal neodymium-doped ZnO and g-C3N4 Z-type heterostructures enhance the photocatalytic efficiency of methylene blue removal

Herein, Nd-ZnO/g-C3N4 (NZCN) composites were obtained by doping rare-earth element Nd with ZnO using a hydrothermal method, coupled with g-C3N4 (CN) electrostatic ultrasonic self-assembly. The NZCN composite exhibited an impressive methylene blue (MB) removal rate of 94.88 %, with a degradation rate of 0.02637 min−1 after 105 min exposure to 500 W xenon lamp irradiations. Comparatively, the degradation rate of MB by the NZCN composite was five and twice times higher than ZnO and CN samples, respectively. This significant improvement can be attributed to the synergistic effect of Nd, ZnO, and CN, which not only widened the light absorption range but also enhanced the density, separation, and transport of photogenerated electrons (e−) and holes (h+), thus improving the photocatalytic performance of the NZCN composites. An in-depth investigation into the photocatalytic reaction process was carried out using free-radical active-species capture experiments, confirming the critical role of h+. Furthermore, the reproducibility and stability of the NZCN composites were assessed over five experimental cycles, demonstrating consistent and stable MB degradation rates of 90.1 % while retaining the crystal structure unchanged. Overall, the construction of rare-earth-metal-doped ZnO and Z-type heterojunctions synergistically improves photocatalytic activity and provides a green and environmentally friendly approach for the removal of organics from wastewater.

Hydrophilic calix[4]arene dye-sensitized Co/g-C3N4 composites with Co single atoms for enhanced visible-light-driven photocatalysis

Single-atom hybrid photocatalysts (Co/g-C3N4/C4EOP) composed of hydrophilic calixarene dyes (C4EOP) and graphite-phase carbon nitrite with monodispersed Co atoms (Co/g-C3N4) are prepared by a facile solution impregnation method, and their photocatalytic performances are evaluated in visible light-driven H2 evolution from water and CO2 conversion. The optimized Co/g-C3N4/C4EOP (1.0 wt%) catalyst exhibits moderate H2 production activity (511 μmol g−1 h−1) and good durability within 60 h (TONC4EOP value of 2255) under visible light. In contrast, the Co/g-C3N4/C4BTP (1.0 wt%) and Co/g-C3N4/M-EOP (1.0 wt%) show much lower activities than Co/g-C3N4/C4EOP (1.0 wt%) under the same conditions. This could be attributed to the higher molar extinction coefficient and better hydrophilicity of C4EOP compared to C4BTP with hydrophobic alkane groups and M-EOP with single D-π-A chain. In addition, Co/g-C3N4/C4EOP (1.0 wt%) catalyst displays highly selective photocatalytic activity for CO2 reduction to CO. This work provides a promising example for the development of efficient dye-sensitized photocatalytic system based on g-C3N4 with non-noble metal for the chemical utilization of solar energy.

Oxygen vacancies mediated enhanced visible-light-driven photocatalytic oxidation of biomass derived 5-hydroxymethylfurfural over V2O5·nH2O/g-C3N4 composite

A series of V2O5·nH2O/g-C3N4 (HVO/CN) heterogeneous composites were synthesized using an ultrasonic method and employed in the photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) towards 2,5-diformylfuran (DFF). The HVO/CN-5 catalyst exhibited the highest photocatalytic performance with a 35.7 % yield and a 84 % of selectivity of DFF under visible light irradiation. A thorough investigation on the synthesized HVO/CN composite was executed to reveal the origin of the high photoactivity. The research results showed that the incorporation of HVO into CN widened the range of the visible-light response and improved the ability to separate the photo-induced charge carriers via a Z-scheme mechanism. Meanwhile, an increased concentration of oxygen vacancies was also observed in the composite, which enhanced the surface OH− content and facilitated the generation of hydroxyl radicals. This change is beneficial to the photocatalytic reaction since that hydroxyl and superoxide radicals are the main reactive species. A possible reaction pathway for the photocatalytic oxidation of 5-HMF to DFF was also suggested. This work may provide insights on the green and sustainable conversion of HMF to DMF via photocatalysis.

Supercritical carbon dioxide-assisted TiO2/g-C3N4 heterostructures tuning for efficient interfacial charge transfer and formaldehyde photo-degradation

Long exposure to formaldehyde has been a concern for causing respiratory problems and TiO2/g-C3N4 composite is a potential choice to address this issue. This study developed a supercritical carbon dioxide (ScCO2)-assisted method to fabricate TiO2/g-C3N4 composites with two distinct heterostructures. The g-C3N4 nanosheet/TiO2 nanoparticle (denoted as type 1 heterostructure) heterojunction could accelerate electron migration because of its large interfacial surface contact. The ternary TiO2{101}/g-C3N4/TiO2{001} heterojunction (denoted as type 2 heterostructure) was synthesized for the first time, further promoting the separation of photogenerated electron/hole pairs under full-spectrum irradiation because it provided an additional migration channel for photocarriers. By loading different amounts of TiO2, the heterostructures were modulated, thereby influencing the photoactivity of the composites. The TiO2/g-C3N4 composite with 58% TiO2 loading possessed the best photocatalytic performance, achieving the highest rate constant for formaldehyde degradation, approximately 7 times higher than pure bulk g-C3N4 under either visible or full-spectrum light. Under full-spectrum irradiation, the maximum decomposition rate approached nearly 100% within 90 min. The tuned heterostructures facilitated the generation of O2·− and·OH, which were dominant active oxygen radicals responsible for formaldehyde removal under light irradiation. Thus, this study developed a green route to synthesize composites with tunable heterojunctions and enhanced photocatalytic activity that can be used for indoor air pollutant degradation.

Fabrication of Ag/WO3/g-C3N4 composites for the photocatalytic degradation of harmful dyes

In the present work, it is noticed that the synthesis of photocatalytic bare and composite materials: i) bare graphitic carbonitride g-C3N4 (GCN), ii) modified with tungsten oxide WO3/g-C3N4 (WGCN), and iii) with both tungsten oxide and silver nanoparticles WO3/Ag/g-C3N4 (WAgGCN), by three different methods: calcination, precipitation, and ultrasonication. Also, their photocatalytic efficiencies were evaluated towards the photodegradation of different dyes under visible, UV, and sunlight irradiations with promising results. Here, the WAgGCN composite showed significant photocatalytic performance to decolorized Methylene Blue (98%) and Crystal Violet (95%), together with high chemical stability and excellent recyclability. The presence of Ag shows the influences of surface plasmon resonance and acts as an electron mediator in the formed heterostructures. The photogenerated holes performed vital roles in the catalytic degradation of dye solutions over the WAgGCN composite catalyst, confirmed by radical trapping experiments. Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) measurements confirmed the mineralization of the dyes.

Fabrication of Z-scheme ZnO/g-C3N4 heterojunction modified by silver nanoparticles for photocatalytic removal of Norfloxacin and Rhodamine B

A novel ternary photocatalyst with a Z-scheme heterojunction was successfully synthesized through the deposition of Ag nanoparticles onto the surface of a ZnO/g-C3N4 composite. The prepared photocatalysts were characterized by XRD, FT-IR, XPS, HRSEM, TEM, DRS, PL, EIS, TPC, and M-S. The photocatalytic performance of the as-synthesized photocatalysts was systematically investigated through the photodegradation of norfloxacin (NOR) and rhodamine B (RhB) under visible light irradiation. The photodegradation efficiency of 5% Ag/ZnO/g-C3N4 (5AZCN) composite photocatalyst reached 86.7% (480 min) and 98.0% (60 min) for NOR and RhB, respectively. Moreover, the apparent rate constants of the 5AZCN composite photocatalysts for NOR and RhB were found to be 3.4 and 22.2 times higher than that of the ZCN composite photocatalysts, respectively. The significantly enhanced photocatalytic performance was ascribed to the widened range of visible light response and the efficient separation and migration of carriers facilitated by the introduction of Ag nanoparticles that functioned as electron transfer mediators. Based on the free radicals quenching experiment and electron spin resonance (ESR) spectroscopy characterization, superoxide radicals (·O2−) were the main reactive species in the photodegradation process. Furthermore, the charge transfer process was proved to be a Z-scheme transfer mechanism. This work provides a promising approach to simply constructing novel efficient Z-scheme photocatalysts for the elimination of environmental pollutants.

Efficient Photocatalytic Degradation of Aqueous Atrazine over Graphene-Promoted g-C3N4 Nanosheets

Atrazine is a systemic herbicide widely used in weed control. In recent years, it has been largely detected in surface and groundwater in several locations all over the world. Photocatalysis is a green and sustainable technology with huge application prospects in pollution control and the degradation of organic water pollutants. In this work, photodegradation of aqueous atrazine was investigated over pristine graphitic carbon nitride (g-C3N4) synthesized via urea pyrolysis and graphene/g-C3N4 composite synthesized via the in situ growth method involving direct deposition of g-C3N4 nanosheets on the graphene surface. The obtained photocatalysts were characterized using transmission and scanning electron microscopy, Fourier-transformed infrared spectroscopy, UV-visible spectroscopy, photoluminescence spectroscopy, X-ray diffraction, and surface area measurements. It was demonstrated that the composite material exhibited remarkable photocatalytic properties for the efficient degradation of aqueous atrazine under visible light at ambient temperature. After 5 h of reaction, atrazine conversion reached 100% in the presence of graphene/g-C3N4 composite, while the pristine g-C3N4 allowed 40% conversion under the same conditions, thus demonstrating the positive effect of graphene on the photocatalytic activity of g-C3N4. Moreover, graphene/g-C3N4 was shown to keep its activity even when it was recycled five times, thus proving its stability and its potential to be used at the industrial scale.

Insights into the organic degradation by sulfite activation with a Fe3O4/g-C3N4 photocatalyst under visible LED: Transformation of SO4•− to 1O2

Sulfite (S(IV))-based advanced oxidation process has attracted widespread attention due to the generation of strongly oxidizing sulfate radicals (SO4•−) and hydroxyl radicals (HO•) for contaminants remediation. However, the contaminant degradation by singlet oxygen (1O2) through a nonradical pathway was still unclear in the S(IV) activation system. Herein, a magnetic Fe3O4/g-C3N4 (MCN) composite was synthesized for the utilization as a visible-light catalyst to activate S(IV) under visible-LED (Vis-LED) for the organic degradation. The incorporation of Fe3O4 in g-C3N4 up-regulated the photocatalytic performance in the S(IV) activation for X-3B degradation, and > 98% of X-3B (20 mg L−1) was degraded with the degradation rate constant (kobs) of 0.110 min−1 within 30 min. The SO4•− and 1O2 produced in the MCN/S(IV)/Vis-LED system were identified as the primary reactive species through the quenching experiments and electron spin resonance. Interestingly, the light-induced generation of superoxide radical (O2•−) played a negligible role in the formation of 1O2, and most of 1O2 was corroborated to be originated from SO4•− besides SO5•−, which was rarely reported in other S(IV) activation processes. The catalysts before and after utilization were characterized to further elucidate the mechanisms for the S(IV) activation. There were two possible pathways for the S(IV) activation: the electron transfer from S(IV) to the photo-generated holes and the ligand-to-metal charge-transfer (LMCT) within the surface Fe(III)−S(IV) complexes. Furthermore, the MCN/S(IV)/Vis-LED system was of high resistance to complex water matrixes (pH, inorganic anions, etc.), demonstrating its application perspective in the purification of wastewater containing organic pollutants.

Bayberry-like Cu3BiS3 with 2D layered nanosheets of rGO and g-C3N4 for effective electrochemical HER activity

Hydrogen production via electrochemical water splitting is still considered as solution for global energy demand. The ternary composite material of copper bismuth sulfide/reduced graphene oxide/graphitic carbon nitride (Cu3BiS3/rGO/g-C3N4) electrocatalyst was produced via hydrothermal for HER activity. The X-ray diffraction study revealed that Cu3BiS3 with carbon composite have orthorhombic phase with an average crystallite size as 43.1 nm. The Raman spectra of Cu3BiS3 with carbon (rGO/g-C3N4) composite revealed the existence of structural defects with ID/IG ratio of 1.01. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies was explored bayberry-like Cu3BiS3 nanosphere formation with finely unified rGO and g-C3N4 sheets. In an alkaline medium, the electrocatalytic performance demonstrates the enhancement of the Cu3BiS3 catalyst due to the addition of rGO/g-C3N4 with the low 111 mV overpotential and small 113 mV/dec Tafel slope value. The electrochemical active surface area (ECSA) of Cu3BiS3 with carbon (rGO/g-C3N4) composite was 127.25 cm2, whereas the ECSA values of Cu3BiS3 and Cu3BiS3/rGO were 34.25 and 86.5 cm2, respectively. The results conclude that π-π interaction among rGO and g-C3N4 can effectively improve the conductivity, active sites, surface area and porous nature of the obtained product, which leads to enhance HER performance. Therefore, morphology tuned carbon composite material would be a promising candidate in forthcoming cost-effective and large-scale water splitting applications.

Layered by layered construction of three novel ZnCo-LDHs/g-C3N4 for the removal of sunset yellow by adsorption-photocatalytic process.

The removal of organic dyes has attracted attention by adsorption-photocatalytic synergetic process in water treatment technology. Three novel ZnCo-LDHs/g-C3N4 were successfully prepared for the first time by layered construction technique through the hydrolysis of triethanolamine in this paper. They exhibited high specific surface area which facilitates the adsorption of sunset yellow (SY) from solution to catalyst surface. All the target pollutant dyes are very effectively removed by the three ZnCo-LDHs/g-C3N4 composites through synergetic effect of adsorption and photocatalysis process under UV irradiation (λ = 365nm). The order of synergistic degradation effect for SY is as follows: ZnCo-LDHs/g-C3N4-3 (99.6%) > ZnCo-LDHs/g-C3N4-2 (99.5%) > ZnCo-LDHs/g-C3N4-1 (99.3%) > pure g-C3N4 (77.4%) > pure ZnCo-LDHs (44.2.6%) at the initial concentration of 75mg L-1. ZnCo-LDHs/g-C3N4-3 has the largest k value (0.0284min-1) in SY degradation, which is 2.8 times that of g-C3N4. ZnCo-LDHs/g-C3N4-3 is a very promising adsorption-photocatalyst for the removal of SY from wastewater. The electron spin resonance experiments demonstrate that OH·, 1O2, and O2- are the dominant active species and oxides SY together. This result demonstrates that the three ZnCo-LDHs/g-C3N4 have practical applications as efficient adsorption-photocatalytic materials and also provides a synergetic strategy for the removal of SY wastewater.

Synthesis of Ag3PO4/Ag/g-C3N4 Composite for Enhanced Photocatalytic Degradation of Methyl Orange.

In this study, we have successfully constructed Ag3PO4/Ag/g-C3N4 heterojunctions via the hydrothermal method, which displays a wide photo-absorption range. The higher photocurrent intensity of Ag3PO4/Ag/g-C3N4 indicates that the separation efficiency of the photogenerated electron-hole pairs is higher than that of both Ag3PO4 and Ag/g-C3N4 pure substances. It is confirmed that the efficient separation of photogenerated electron-hole pairs is attributed to the heterojunction of the material. Under visible light irradiation, Ag3PO4/Ag/g-C3N4-1.6 can remove MO (~90%) at a higher rate than Ag3PO4 or Ag/g-C3N4. Its degradation rate is 0.04126 min-1, which is 4.23 and 6.53 times that of Ag/g-C3N4 and Ag3PO4, respectively. After five cycles of testing, the Ag3PO4/Ag/g-C3N4 photocatalyst still maintained high photocatalytic activity. The excellent photocatalysis of Ag3PO4/Ag/g-C3N4-1.6 under ultraviolet-visible light is due to the efficient separation of photogenerated carriers brought about by the construction of the Ag3PO4/Ag/g-C3N4 heterostructure. Additionally, Ag3PO4/Ag/g-C3N4 specimens can be easily recycled with high stability. The effects of hydroxyl and superoxide radicals on the degradation process of organic compounds were studied using electron paramagnetic resonance spectroscopy and radical quenching experiments. Therefore, the Ag3PO4/Ag/g-C3N4 composite can be used as an efficient and recyclable UV-vis spectrum-driven photocatalyst for the purification of organic pollutants.

Using a Novel Heterojunction CoWO4/g-C3N4 as Visible Light Photocatalyst for Photodegradation of Organic Pollutant

Methylene Blue (MB) is a common dye that has various applications in different fields, including medicine, biology, and environmental science. While it can be beneficial in certain contexts, it can also have negative effects on the environment under certain circumstances. In this study, the photodegradation of MB under visible light irradiation using a novel heterojunction CoWO4/g-C3N4 catalyst was investigated. A series of CoWO4/g-C3N4 composites were synthesized and characterized using various techniques, including XRD, SEM, SEM-EDS, FT-IR, and UV–DRS. The results revealed that the 0.3CoWO4/g-C3N4 composite showed the highest efficiency (93%) in degrading MB during the 80-minute photodegradation process, aligning with the pseudo-first-order kinetics. The results provide clear evidence that the formation of CoWO4/g-C3N4 heterojunction greatly enhances the efficiency of photocatalysis by facilitating the swift separation of electron-hole pairs and boosting the redox capability. Additionally, the photodegradation efficiency remained above 90% even after four cycles, suggesting the stability of the catalyst.

First-rate photocatalytic degradation of wastewater pollutants and antibacterial activities and H2 evolution of hierarchical WO3 embedded BiOCl/g-C3N4 nanocomposites

Highly efficient and stable WO3-embedded hierarchical BiOCl/g-C3N4 (WBG) composites have been synthesized by a two-step solvothermal route. Phase identification and other structural and microstructural parameters are evaluated by analyzing the XRD pattern of respective composites employing the Rietveld refinement technique. HRTEM images reveal that BiOCl and WO3 nanoparticles of size 20–25 and 4–6 nm are embedded uniformly on the surface of g-C3N4 nanosheets respectively. The nanocomposites offered outstanding photocatalytic performance by showing degradation of colored dyes, colorless pollutants, tetracycline antibiotics and reduction of Cr (VI). About 95% of RhB dyes within 8 min, ∼91% phenol within 150 min, ∼85% tetracycline (TC) within a record 20 min have been degraded, and 98% Cr (VI) reduced within 10 min from wastewater under sunlight irradiation in the presence of the WBG3 nanocomposite. In addition, the WBG3 nanocomposite shows a significant photocatalytic H2 production rate of 2 mmol.h−1 g−1. Apart from that, the growth of gram-positive and gram-negative pathogenic bacteria is notably inhibited by WBG nanocomposite, comparable to the same concentration of the pure drug. This work provides a strong framework to fabricate future-generation photocatalysts for the remediation of organic pollutants and heavy metals and for producing solar light-driven hydrogen evolution.

Facile synthesis of ZnO/Ag/g-C3N4 nanocomposites for multiple applications in photocatalytic degradation and photoactivated NO2 sensing

It is important to seek effective strategies to fabricate nanomaterials with multi-functionalities in noxious gas detection and poisonous waste treatment. Herein, Ag nanoparticles and g-C3N4 nanosheets co-modified ZnO heterostructure was synthesized via a one-step polymer-network gel method, which is used as both photocatalyst and sensing material. Being a visible-light-driven photocatalyst, the ternary ZnO/Ag/g-C3N4 composite produced 100 % Rhodamine B degradation within 30 min with good cycling stability. Besides, the gas sensor based on ZnO/Ag/g-C3N4 exhibited superb room-temperature sensing performance under neutral light excitation, with a response value of 15.3–5 ppm NO2 and a lower detection limitation. The excellent performance was mainly attributed to the significantly enhanced visible-light absorption as well as effectively suppressed charge recombination because of the synergism between the individual components. Moreover, the formation of g-C3N4 nanosheets during thermal oxidation etching plays a critical role in improving the surface area and enriching the surface oxygen vacancies. Thus, this work provides novel insights for the synthesis and multi-applications of ZnO/Ag/g-C3N4 heterostructure with high performance.

Facile fabrication of ultra-light N-doped-rGO/g-C3N4 for broadband microwave absorption

“Thin thickness”, “lightweight”, “wide absorption bandwidth” and “strong absorption” are the new standards of contemporary science and technology for microwave absorption(MA) material. In this study, N-doped-rGO/g-C3N4 MA material was prepared for the first time by simple heat treatment, which the N atoms were doped into rGO and g-C3N4 was dispersed on the surface of N-doped-rGO, and its density is only 0.035 g/cm3. The impedance matching of the N-doped-rGO/g-C3N4 composite was well adjusted by decreasing the dielectric constant and attenuation constant due to the g-C3N4 semiconductor property and the graphite-like structure. Moreover, the distribution of g-C3N4 among N-doped-rGO sheets can produce more polarization effect and relaxation effect by increasing the lamellar spacing. Furthermore, the polarization loss of N-doped-rGO/g-C3N4 could be increased successfully by doping N atoms and g-C3N4. Ultimately, the MA property of N-doped-rGO/g-C3N4 composite was optimized significantly, with a loading of 5 wt%, the N-doped-rGO/g-C3N4 composite exhibited the RLmin of −49.59 dB and the effective absorption bandwidth could reach 4.56 GHz when the thickness was only 1.6 mm. The “thin thickness”, “lightweight”, “wide absorption bandwidth” and “strong absorption” of MA material are actually achieved by the N-doped-rGO/g-C3N4.

A Novel Heterojunction CuWO4/g-C3N4 Photocatalyst for Removal of Organic Pollutant under Visible Light Irradiation

In this study, a series of CuWO4/g-C3N4 composites were synthesized using a facile construction method. The structural characteristics of the composites were examined using various techniques, including XRD, SEM, SEM-EDS, FT-IR, and UV–DRS. The photocatalytic performance of the CuWO4/g-C3N4 nanocomposites was evaluated in the degradation of methylene blue (MB) under visible light irradiation. The findings revealed that the CuWO4/g-C3N4 composite with a mass ratio of 10% CuWO4 displayed the highest efficiency (89%) in degrading MB during an 80-minute photodegradation process, which was consistent with the pseudo-first-order kinetics. These results clearly demonstrate that the formation of a Z-scheme CuWO4/g-C3N4 heterojunction significantly improves the photocatalytic efficiency by promoting rapid separation of electron-hole pairs and enhancing the redox capability. Additionally, the photodegradation efficiency remained above 85% even after four cycles, suggesting the stability of the catalyst.

Facile design of surface electric field driven tourmaline/g-C3N4 layered stacked photocatalysts with enhanced photocatalytic activity for antibiotic removal

In the field of photocatalysis, Graphitic carbon nitride (g-C3N4) has received a lot of attention for its superior functionality and benefits. However, it suffers from the fatal defect of low charge separation efficiency, which is well addressed by tourmaline's self-contained surface electric field. In this work, tourmaline/g-C3N4 (T/CN) composites were successfully synthesized. Due to its surface electric field effect, tourmaline and g-C3N4 are stacked on top of each other. It makes its specific surface area increase greatly and more active sites are exposed. Additionally, the rapid separation of photogenerated electron holes under the action of electric field promotes the photocatalytic reaction. T/CN exhibited excellent photocatalytic performance under visible light, with 99.9% Tetracycline (TC 50 mg L−1) removal after 30 min. Compared to tourmaline (0.0160 min−1) and g-C3N4 (0.0230 min−1), the T/CN composite's reaction rate constant (0.1754 min−1) was 11.0 and 7.6 times higher. A series of characterizations also determined the structural properties and catalytic performance of the T/CN composites, which were found to have a larger specific surface area, narrower band gap, and higher charge separation efficiency compared to the monomer. In addition, the toxicity of tetracycline intermediates and their degradative pathways were investigated, and the toxicity of the intermediates was found to be reduced. Given the quenching experiments and active substance determination, it was also found that h+ and ·O2− play a major role. This work provides more inspiration for photocatalytic material performance research as well as green innovation for environmental management.

H2O2-assisted hydrothermal formation of porous N-graphyne/g-C3N4 with high-efficiency photocatalytic performance

Surface modification is critical approach for improving the pollutant removal rate of the promising g-C3N4-based photocatalysts. Here, a series of porous N-graphyne/g-C3N4 composites are fabricated via a facile hydrothermal process in the assistance of H2O2. A maximum of 7.67 folds enhancements is verified for photocatalytic degradation of rhodamine B by as-prepared composites in comparison with g-C3N4 under visible light. The optimum removal ratios of RhB can reach 86.8 % within only 9 min. And, the superior photocatalytic stability is confirmed by five cycling photocatalytic tests. In short, improved photocatalytic activity is ascribed to enhanced visible light response, faster separation rate, and more active sites in the composites. This work first initiates a novel route via design/construction of porous N-graphyne/g-C3N4 photocatalysts for highly efficient pollutant degradation in waste water.

Doping vs. heterojunction: A comparative study of the approaches for improving the photocatalytic activity of flower-like Bi2WO6 for water treatment with domestic LED light

In this work, Bi2WxMo1–xO6 solid solutions and Bi2WO6/g-C3N4 composites were synthesized by a simple hydrothermal method, characterized by a complex of physicochemical methods and used in the decomposition of organic pollutants under visible light to comprehensively compare different modulating techniques. The highest efficiency was detected for Bi2W0.5Mo0.5O6 in the degradation of methylene blue (conversion of 52.9%, TON = 0.022), indicating the attractiveness of the doping strategy. Excellent results were achieved with small amounts of H2O2 in the photodegradation of methylene blue (conversion of 97.9%, TON = 0.040) and phenol (conversion of 81.2%, TON = 0.056).