3N4 Heterojunction Research Articles

A novel carbon doped CeO2/g-C3N4 heterostructure for disinfection of microorganisms and degradation of Malachite green and Amoxicillin under sunlight

The fabrication of semiconductor heterojunction with defect engineering is an efficient technique to boost photocatalytic activity. In this study, a novel step-scheme heterojunction C-CeO2/g-C3N4 nanocomposite was developed via the hydrothermal method for the degradation of aqueous dye and antibiotics in sunlight. The photocatalytic experiment of the CeO2/g-C3N4 heterojunction nanocomposite reveals superior photocatalytic activity and significant reusability. Further, 91.9 % of Malachite green (MG) and 87.5 % of Amoxicillin(AMX) were degraded by C-CeO2/g-C3N4 nanocomposite under 150 mins of sunlight irradiation, which is ∼ 1.78 folds of the photodegradation performance of C-CeO2. The decomposition of MG and AMX into non-toxic secondary compounds was verified by total organic carbon and high-performance liquid chromatography analysis. Further, the migration and separation of charge carriers due to photons were confirmed through electrochemical analysis and, photoluminescence spectroscopy. The potential S-Scheme charge transfer pathway for improved photocatalytic activity was postulated via the quenching experiment, Mott Schottky (M-S) plot, and XPS Valance band spectroscopy (VB-XPS). In addition, the C-CeO2/g-C3N4 nanocomposite displays excellent bactericidal and fungicidal activity against pathogenic microorganisms S. aureus, E. coli, and C. albican. Hence, the synthesized S-Scheme heterojunction C-CeO2/g-C3N4 nanocomposite is an ideal catalyst for the detoxification of industrial wastewater.

2D Z-scheme ZnIn2S4/g-C3N4 heterojunction based on photoelectrochemical immunosensor with enhanced carrier separation for sensitive detection of CEA

Semiconducting materials based on photoelectrochemical (PEC) sensors have been widely utilized for detection. Meanwhile, the sensitivity of the PEC sensor was limited by low-efficiency carrier separation. Thus, a novel sandwich-type PEC bioimmunosensing based on 2D Z-scheme ZnIn2S4/g-C3N4 heterojunction as a photosensitive material and BiVO4 as a photoquencher was designed for the sensitive detection of carcinoembryonic antigen (CEA). Firstly, the 2D ZnIn2S4/g-C3N4 structure provided a multitude of activated sites which facilitated the loading of the capture antibody (Ab1). Secondly, the Z-scheme heterojunction had a high redox capacity while promoting the rapid separation and migration of photogenerated electron-hole pairs (e−/h+). Thus it was able to consume more electron donors to a certain extent, resulting in a higher initial photocurrent. In addition, BiVO4 with large spatial potential resistance was introduced for the first time to realize signal amplification. BiVO4 could not only compete with substrate materials for electron donors, but also effectively prevent electron donors from contacting the substrate, further reducing the photocurrent signal. Under optimized conditions, the sensor had a favorable detection range (0.0001–100 ng/mL) to CEA and a low detection limit of 0.03 pg/mL. With high specificity, excellent stability, and remarkable reproducibility, this sensor provided a new perspective for constructing accurate and convenient PEC immunosensor for bioanalysis and early disease diagnosisdisease diagnosis.

Recent Advances in LDH/g-C3N4 Heterojunction Photocatalysts for Organic Pollutant Removal.

Environmental pollution has been decreased by using photocatalytic technology in conjunction with solar energy. An efficient method to obtain highly efficient photocatalysts is to build heterojunction photocatalysts by combining graphitic carbon nitride (g-C3N4) with layered double hydroxides (LDHs). In this review, recent developments in LDH/g-C3N4 heterojunctions and their applications for organic pollutant removal are systematically exhibited. The advantages of LDH/g-C3N4 heterojunction are first summarized to provide some overall understanding of them. Then, a variety of approaches to successfully assembling LDH and g-C3N4 are simply illustrated. Last but not least, certain unmet research needs for the LDH/g-C3N4 heterojunction are suggested. This review can provide some new insights for the development of high-performance LDH/g-C3N4 heterojunction photocatalysts. It is indisputable that the LDH/g-C3N4 heterojunctions can serve as high-performance photocatalysts to make new progress in organic pollutant removal.

Photocatalytic degradation of sulfamethoxazole over S-scheme Fe2O3/g-C3N4 photocatalyst under visible light

The application of promising g-C3N4 has been limited by poor photogenerated electron-hole separation and limited absorption for visible light. Sulfamethoxazole (SMX) is a typical antibiotic drug that is used worldwide and hard to be disposed through conventional wastewater treatment methods. Herein, S-scheme Fe2O3/g-C3N4 heterojunction was successfully prepared via a facile one-step sintering method and applied to photodegrade SMX under visible light irradiation. The integration of Fe2O3 and g-C3N4 shows superior charge separation and light absorption ability. As a result, the removal efficiency of 11 wt% Fe2O3/g-C3N4 reaches to 99.2% within 30 min, which is visibly higher than 59.5% of pure g-C3N4. ·O2− and ·OH are demonstrated to be the predominant active species for SMX photodegradation, and the possible degradation pathway is also proposed based on electronic band structure of Fe2O3/g-C3N4 heterojunction. This study presents a facile construction of g-C3N4 based S-scheme photocatalyst and offers an environmentally friendly approach to effectively remove organic pollutants using renewable solar energy.

In situ solid-state fabrication of Z-Scheme BiVO4/g-C3N4 heterojunction photocatalyst with highly efficient-light visible activity and their antibacterial properties against bacterial pathogens

Here, BiVO4/g-C3N4 composite photocatalyst with various weight percent of BiVO4 were synthesized by in-situ solid-state fabrication via calcination process. Photocatalyst was characterized by various analytical techniques (XRD, SEM, TEM, UV–vis-DRS, and TGA). The SEM and TEM results showed that composites materials BiVO4 dispersed uniformly on the surface of g-C3N4 sheets, revealing that g-C3N4 sheets was probably a promising support for in-situ growth of nano-size materials. The achieved intimate interfacial contact between BiVO4 and g-C3N4 promoted the charge transfer and inhibited recombination rate of photogenerated electron-hole pairs, which significantly improved the photocatalytic activity. Remarkably, catalytic efficiency of BiVO4/g-C3N4 composites has been demonstrated, via photodegradation of organic pollutants such as rhodamine-B (RhB) and ciprofloxacin (CIP). The 5 wt.% BiVO4/g-C3N4 showed excellent photocatalyst activity and potentially degraded RbB (98 %) and CIP (95 %) in 75 min of irradiation time in the presence of visible light. Moreover, radical trap experiment indicated that the –•O2 and •OH acted as main reactive species for photocatalytic degradation. In addition, BiVO4/g-C3N4 nanocomposite showed strong antibacterial potential against bacterial pathogens; E. coli ATCC-15224, Staphylococcus aureus MTCC-3160 and Pseudomonas aeruginosa PAO1. Studies revealed that depended on time and BiVO4/g-C3N4 concentration, bacterial growth, and viability (CFU count) was consistently declined. The increasing doses of BiVO4/g-C3N4 significantly (p ≤ 0.05) inhibited the virulence factors like pyoverdin, pyocyanin, elastase, exoprotease, rhamnolipid, and swimming motility of P. aeruginosa PAO1 by 76.9, 49.0, 71.1, 53.3, 89.5, and 60 %, respectively. Furthermore, biofilms formed by E. coli, S. aureus and P. aeruginosa PAO1 were maximally inhibited at 10 µgmL−1 BiVO4/g-C3N4 to a maximum of 67, 56 and 56 %, respectively. Also, exopolysaccharide (EPS) releasing ability of isolates were suppressed by BiVO4/g-C3N4. The fluorescently labelled probe DCFH-DA staining of bacterial isolates showed nanocomposite-dependent increase in ROS production and superoxide radicals. The photodegradation of RhB and (CIP) recommends that synthesized BiVO4/g-C3N4 nanocomposite have strong photocatalytic properties. Summarily, newly synthesized BiVO4/g-C3N4 photocatalyst can be employed as an alternative to remediate the environmental pollution as well as a therapeutic agent for topical administration in controlling the pathogenic infections.

Constructing 3D flower-like S-scheme N–Bi2O2CO3/g-C3N4 heterojunction with enhanced photocatalytic performance

Mineral processing wastewater contains a lot of organic matter and heavy metal ions, and poor self-degradation ability makes it a key treatment object in environmental treatment. Photocatalysis is a promising technology to efficiently mineralize refractory contaminants from wastewater. In this work, 3D flower-like S-scheme N–Bi2O2CO3/g-C3N4 heterostructures were successfully constructed by hydrothermal method with the auxiliary of ionic liquids. The photocatalytic experiments show that the catalytic activity of heterojunction photocatalysts was significantly higher than that of bare g-C3N4 and N–Bi2O2CO3 for the degradation of two pollutants. NBOC/CN-2 shows the highest photocatalytic performance, and the degradation efficiency of sodium isobutyl xanthate (SIBX) on NBOC/CN-2 is 1.85 and 3 times that of bare g-C3N4 and Bi2O2CO3, respectively. The degradation efficiency of m-Cresol on NBOC/CN-2 is 8.34 and 6.93 times that of bare g-C3N4 and N–Bi2O2CO3, respectively. This significantly enhanced photocatalytic activity is attributed to the formation of flower-like heterojunctions, which can greatly increase the specific surface area and facilitate the separation and migration of photogenerated carriers. Total organic carbon (TOC) experiment proves that the two pollutants are effectively mineralized under the action of the prepared photocatalyst. The degradation path of m-Cresol degradation products was inferred based on the ion fragments. The capture experiment and Nitro-blue tetrazolium (NBT)-•O2− measurement show that superoxide radical plays a major role in photocatalytic degradation. The outstanding stability of the prepared flower-like heterojunction samples was examined by cyclic experiments. The S-scheme charge transfer mechanism has been proposed to explain the boosted activity of the flower-like heterojunction photocatalyst. This work provides a new idea for the design of efficient and stable g–C3N4–based photocatalyst for the photocatalytic degradation of refractory wastewater.

Zn2SnO4/SnO2/g-C3N4 heterojunction: High efficiency photocatalytic degradation of Rhodamine B in simulated visible light

Photocatalysis is an effective solution to wastewater treatment problems, and semiconductor heterojunctions for photocatalysis can effectively separate photogenerated carriers to improve the performance of photocatalytic degradation of pollutants. In this paper, a ternary composite photocatalyst with a heterojunction structure (Zn2SnO4/SnO2/g-C3N4) was prepared to photodegradeRhodamine B in simulated visible light. The experimental findings demonstrate that the Zn2SnO4/SnO2/g-C3N4 photodegradation rates and efficiencies for RhB are much higher than those for SnO2, g-C3N4, SnO2/g-C3N4, and Zn2SnO4/SnO2. We obtained a 3:1 mass ratio of Zn2SnO4/SnO2 to g-C3N4 by optimization, with a maximum degradation rate of 99.5 % and a maximum kinetic constant k of 0.692 min-1·g−1 for the photocatalytic removal of RhB by Zn2SnO4/SnO2/g-C3N4. The radical trapping experiments suggest the primary role of ·O2– for the photocatalytic removal of RhB. The ternary composite photocatalyst Zn2SnO4/SnO2/g-C3N4 shows promise for potential applications in RhB degradation owing to its exceptionally.

Construction of coordination bond electron bridge boosting interfacial electron transfer to enhance bifunctional photocatalytic activity of TiO2/g-C3N4 heterojunction

The weak interfacial coupling of heterojunction catalysts leads to a large barrier, which inhibits interfacial electron transfer and limits the catalytic efficiency. Herein, a unique Ti-N coordination electron bridge has been designed and constructed in TiO2/g-C3N4 heterojunction with a tightly-coupled interface by using a newly designed topotactic transition and in-situ pyrolysis method. Experimental data and characterization analyses indicate that abundant stacking faults and surface oxygen vacancies change the surface atomic coordination environment and induce the formation of Ti-N coordination bond electron bridges. XPS, TA-PL probing experiment, and EPR analysis indicate a S-scheme electron transport mechanism. The synergistic effect of internal electric field and Ti-N electron bridge promote the efficient S-scheme electron transport, which facilitates the spatial separation of strong oxidizing holes and strong reducing electrons. The hierarchical nanoflower structure benefits electrolyte diffusion and reaction species adsorption. The above virtues endowed the catalyst with enhanced bifunctional photocatalytic activity for hydrogen evolution (1.89 mmol·g−1·h−1) and methyl blue degradation (0.114 min−1), which are 3.2 and 1.9 times that of the bare TiO2. This work opens a new avenue for the construction of heterojunctions and the optimization of interface carrier transfer, providing important insights for synthesizing photocatalysts with excellent activity and stability.

Construction of a stable S-scheme NiSnO3/g-C3N4 heterojunction on activated carbon fibre for the degradation of glyphosate in water under flow condition

Creating light-harvesting heterojunctions as a photocatalyst is critical for efficiently treating organics-laden wastewater. Yet the materials stabilization and limited reusability hinder their practical applications. In this study, an S-scheme heterojunction in the Sn-based perovskite and g-C3N4 (gCN) composite, supported on an activated carbon fiber (ACF) substrate, is developed for glyphosate (GLP) degradation under water under flow conditions. The reusable NiSnO3-gCN/ACF photocatalyst was synthesized using a simple wet impregnation and calcination method. The supported photocatalyst achieved 99% GLP-removal at 4 mL/min water flowrate and 1.25 g/m2 of photocatalyst loading in ACF. The photocatalyst showed a stable structure and repeat photocatalytic performance across 5 cycles despite prolonged visible light exposure under flow conditions. The materials stability is attributed to the effective dispersion of NiSnO3-gC3N4 in ACF, preventing the photocatalyst from elution in water flow. Radical trapping experiment revealed the superoxide and hydroxyl radicals as the primary reactive species in the GLP-degradation pathway. A plausible S-scheme mechanism was proposed for heterojunction formation, based on the high resolution deconvoluted spectra of X-ray photoelectron spectroscopy and the radical trapping experimental results. The inexpensive Sn-based perovskite synthesized in this study is indicated as an alternative to Ti-based perovskites for wastewater remediation application.

Dual S-Scheme Heterojunction CdS/TiO2/g-C3N4 Photocatalyst for Hydrogen Production and Dye Degradation Applications.

This study investigated a ternary CdS/TiO2/g-C3N4 heterojunction for degrading synthetic dyes and hydrogen production from aqueous media through visible light-initiated photocatalytic reactions. CdS, TiO2, and g-C3N4 were combined in different mass ratios through a simple hydrothermal method to create CdS/TiO2/g-C3N4 composite photocatalysts. The prepared heterojunction catalysts were investigated by using FTIR, XRD, EDX, SEM, and UV-visible spectroscopy analysis for their crystal structures, functional groups, elemental composition, microtopography, and optical properties. The rhodamine B dye was then degraded by using fully characterized photocatalysts. The maximum dye degradation efficiency of 99.4% was noted in these experiments. The evolution rate of hydrogen from the aqueous solution with the CdS/TiO2/g-C3N4 photocatalyst remained 2910 μmol·h-1·g-1, which is considerably higher than those of g-C3N4, CdS, CdS/g-C3N4, and g-C3N4/TiO2-catalyzed reactions. This study also proposes a photocatalytic activity mechanism for the tested ternary CdS/TiO2/g-C3N4 heterojunctions.

Synthesis of a double type-II CdS/Zn2In2S5/g-C3N4 heterojunction photocatalyst for the photodegradation of tetracycline under visible light

Herein, the ternary CdS/Zn2In2S5/g-C3N4 (CdS/ZIS/CN) heterojunction photocatalyst was successfully prepared via a one-pot method for photodegradation of tetracycline (TC) under visible light irradiation. The surface morphology, structure and optical properties of the prepared photocatalytic material were analyzed by XRD, SEM, TEM, UV–vis DRS, FT-IR and PL. Moreover, the experimental results exhibited that the ternary CdS/ZIS/CN photocatalyst revealed excellent photocatalytic activity compared with g-C3N4. In this work, 94.73% of TC (20 mg/L, pH=11) was degraded by 0.5 g/L 30CdS/ZIS/CN within 60 min of visible light irradiation. Additionally, the degradation rate of the photocatalyst decreased by about 9.41% after the fourth cycle, indicating its high stability and reusability. Subsequently, a possible double type-II mechanism of photodegradation was eventually provided based on active radical capture experiments. The current investigation provided a promising strategy to construct the high-efficiency heterojunction photocatalyst to degrade antibiotic contaminants.

Recyclable and flexible Bi(Ho3+-Yb3+)OBr/g-C3N4 composite porous fiber for efficient water purification and real-time temperature sensing.

Herein, an electrospinning porous nanofiber with large specific surface area, excellent flexibility, remarkable tensile strength, and high stability of thermal degradation has been developed by loading Ho3+/Yb3+ co-doped BiOBr/g-C3N4 (BHY/CN) heterojunction photocatalysts on polyacrylonitrile (PAN) nanofibers. The optimized BHY/CN-2 nanofiber demonstrates outstanding photocatalytic activity for the degradation of 98.83% tetracycline (TC, 60min) and 99.06% rhodamine B (RhB, 90min) under simulated sunlight irradiation, and maintains a high level of reusability and recycling stability in three cycles. In addition, temperature monitoring of the catalytic degradation process can be feedback by (5F4, 5S2) → 5I8 and 5F5 → 5I8 radiation transitions of Ho3+ with excellent sensitivity. More importantly, the nanofiber luminescence performance is enhanced by the doping of g-C3N4, which maintain the effective upconversion luminescence properties even in water, providing a reliable reference for real-time monitoring and feedback of the operating temperature, and further expanding the application fields of photocatalysts.

Defect engineering in 0D/2D TiO2/g-C3N4 heterojunction for boosting photocatalytic degradation of tetracycline in a tetracycline/Cu2+ combined system

It has been increasingly significant to take advantage of defect engineering in hybrid photocatalysts, aiming to showing novel properties in the remediation of combined pollution such as antibiotic-heavy metal pollution. Herein, a hierarchical 0D/2D TiO2/g-C3N4 heterojunction was fabricated and defects were introduced into the binary-hybrid structure with separate plasma treatment for the each single component. Results show that defect construction on TiO2/CN can exhibit “anisotropic-trapping” effect, where TiO2/D-CN shows stimulation effect while D-TiO2/CN and D-TiO2/D-CN show inhibition on the degradation of tetracycline in the presence of Cu2+. TiO2/D-CN can inhibit the accumulation of Cu2+ and avoid the coverage of active site during the photocatalytic process in contrast to the non-defective or other defective materials. Simultaneously, the formed Cu sites exhibited surface plasmon resonance effect that can enhance the absorption of light, further promoting the photocatalytic degradation of tetracycline. These findings provide new insights into defect construction on binary-heterojunction for the treatment of combined pollution in water.

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 interfacial synergistic effect AlN/g-C3N4 2D/2D Z-type heterojunction for high-performance and stable visible-light photocatalytic removal of Rhodamine B and tetracycline

This study featured the synthesis and characterization of a highly effective AlN/g-C3N4 composite photocatalyst using a combination of physical grinding and calcination methods. The composite material exhibited a unique two-dimensional/two-dimensional (2D/2D) structure, with flocculent g-C3N4 uniformly coated on the surface of AlN. A series of characterization techniques including FE-SEM, TEM, XRD, FT-IR and XPS committed the successful formation of the AlN/g-C3N4 heterostructure. The AlN/g-C3N4 composite demonstrates the improved catalytic efficiency compared to pure AlN, which can be evidenced by its exceptional photocatalytic degradation performance under visible-light irradiation. The AlN/g-C3N4 composite materials exhibited significant degradation of (RhB) and tetracycline (TC). Especially, the 20 % AlN/g-C3N4 component showed particularly remarkable adsorption and catalytic activity, with 98.4 % degradation of RhB solution in 25 min and 83.0 % degradation of TC solution in 60 min, with efficiencies about 3.9 and 6.8 times higher than that of pure g-C₃N4, attributed to its larger specific surface area and a smaller pore structure compared to pure g-C3N4. Moreover, the AlN/g-C3N4 heterojunction exhibited outstanding stability and reusability throughout four consecutive experimental cycles, highlighting its long-lasting and reliable performance. FT-IR analysis confirmed the structural stability of the composite material, and the free radical experiments revealed the dominant role of the holes (h+) free radical in the photocatalytic reaction. Additionally, UV–vis diffuse reflectance and Mott-Schottky tests supported the Z-type charge carrier transport route as the photocatalytic mechanism. Overall, the AlN/g-C3N4 heterostructure have shown great potential as a highly efficient photocatalyst for pollutant degradation, due to its unique structure, high specific surface area, and effective charge carrier separation, making it a promising material for diverse environmental applications.

Weak force-polarization driven exceptional piezo-photocatalysis by coupling dual-active piezoelectric semiconductors in NaNbO3/g-C3N4 heterojunction

Photocatalysis is a green and sustainable technology for pollution control, but has the disadvantage of fast recombination of photogenerated charges. Piezocatalysis has recently been widely studied for environmental purification, while it always involves the high-frequency ultrasonic vibration that inevitably causes high energy consumption. In this work, a water flow weak force-driven piezo-photocatalytic system that integrates light and stress dual-responsive components is developed in NaNbO3/g-C3N4 heterojunction. As piezoelectric semiconductors with both piezoelectric and semiconducting properties, the piezoelectric polarization field of NaNbO3 and g-C3N4 induced by high-speed stirring not only produces strong polarization, but also directly triggers efficient piezocatalysis, and the spatial separation of interfacial carriers is accompanied by the formation of type-II heterojunction. The above merits endow NaNbO3/g-C3N4 with outstanding water flow-triggered piezo-photocatalytic degradation for various antibiotics and drugs, including tetracycline hydrochloride (TC), oxytetracycline (OXY), ciprofloxacin (CIP), chloramphenicol (CHL), and paracetamol (PAR). Specifically, the TC degradation efficiency reaches up to 87.3 % within only 10 min, which makes it one of the best piezo-photocatalysts, even exceeding those irradiated by ultrasound. This work may open up a reference perspective for the engineering design of dual-active piezo-photocatalyst systems, and for the in-situ purification of diversified wastewaters on the basis of hydrodynamic properties.

Constructed a novel of Znln2S4/S-C3N4 heterogeneous catalyst for efficient photodegradation of tetracycline.

Despite S-doped C3N4 can exhibit more efficient photo-reactivity than pure C3N4, there is still some space to further improve the detaching efficiency of electron-hole and enhance the photocatalytic efficiency of S-C3N4. The construction of heterojunction is an effective method to promote the photocatalytic efficiency. ZnIn2S4, as a novel photocatalyst, its VB (1.37 V) and CB (- 1.09 V) can match with S-C3N4. Therefore, we hope to construct the ZnIn2S4/S-C3N4 heterojunction for boosting the photocatalytic activity of S-C3N4. In this paper, ZnIn2S4/S-C3N4 heterojunction was prepared through hydrothermal method using S-C3N4, ZnCl2, InCl3·4H2O, and thioacetamide as raw materials and heated at 160 °C for 16 h. The optimum 18% ZnIn2S4/S-C3N4 nanocomposites exhibit dramatically enhanced photocatalytic performance for degradation of tetracycline with 86.3% removal rate within 120 min, higher than 50% degradation efficiency of pure S-C3N4. And in the process of photodegradation for tetracycline, the largest contribution rate is the photo-excited cavity (h+), followed by ·O2- and ·OH. Herein, we have provided a good example for removing antibiotic residues by using S-C3N4-based heterojunction towards environmental remediation.

Dual-Functional S-Scheme Fe3O4/TiO2/g-C3N4 double-heterostructure bridged by TiO2 for collaborative removal of U(VI) and Sb(III)

Exploiting dual-functional photocatalysts to reduce U(VI) and oxidize Sb(III) is a challenging but efficient way of achieving simultaneous purification. Herein, Fe3O4/TiO2/g-C3N4 (FTC) double-heterostructures with customized stacking order were designed as a dual-functional photocatalyst to collaborative remove U(VI) and Sb(III). When introducing TiO2/g-C3N4 heterojunction and bridging it with Fe3O4/TiO2 using TiO2 as the intermediate layer, FTC showed outstanding photocatalytic activity and can simultaneously achieve 96.5% U(VI) reduction and 88.5% Sb(III) oxidation under sunlight, achieving 90.9% and 85.8% in natural wastewater. The constructed FTC architecture of an S-scheme framework can achieve efficient co-removals of U(VI) and Sb(III) by enhancing the separation and transferal of photoexcited charge carriers with outstanding redox ability employing different reaction sites. TiO2 and g-C3N4 accumulated electrons and holes, respectively, and completed concurrent redox reactions, following the path determined by N(g−C3N4) and O(TiO2), which enhanced the separation of photoexcited carriers. The two-way effect of O2• ⁻ activated by FTC supported positive feedback coupling relationships between the reduction of U(VI) and Sb(III) oxidation. This study not only fulfills the co-removal of U(VI) and Sb (III) for the first time with a capacity of 170.6 and 15.9 mg/g in engineering applications, but also proposes the reaction mechanism of a two-step continuous concerted redox reaction causing high removal determined by the electronic structure, so it lays a foundation for further development of highly efficient and stable heterojunction photocatalysts with concerted effects applied in complex wastewater treatment.

A bifunctional heterostructured membrane for efficient emulsion separation and photocatalytic degradation of waterborne organic pollutants

Oily wastewater discharge from industrial activities and oil spills constitutes a crucial environmental issue exacerbated by the presence of water-soluble organic pollutants. Developing efficient superwetting membrane materials capable of separating oil and water while degrading water-soluble organic pollutants is therefore highly desirable. In this study, we prepared I-doped Bi2O2CO3/g-C3N4 heterojunction structures using a hydrothermal method utilizing graphitic carbon nitride (g-C3N4) as the carbon source, which were uniformly distributed on the mesh of Co3O4 nanowire clusters to obtain the heterojunction membrane. The heterojunction membrane demonstrates superhydrophilicity and underwater superoleophobicity, with excellent separation efficiency and outstanding permeability for oil-in-water emulsions. Additionally, the membrane exhibits good stability, superior anti-corrosive property, remarkable reusability, and near-complete degradation of several water-soluble organic dyes under visible-light irradiation. Therefore, this study provides a novel design strategy for multifunctional membranes that achieve effective treatment of complex oil-containing wastewater.

Hydrothermal synthesis of (m-t)BiVO4/g-C3N4 heterojunction for enhancement in photocatalytic degradation of imidacloprid

Bismuth vanadate (BiVO4) has gained significant attention as a photocatalyst due to lower band gap energy and its effectiveness in the degradation of both organic and inorganic pollutants. In this study, BiVO4 and nanocomposites of BiVO4 with g-C3N4 were synthesized by varying g-C3N4 compositions using hydrothermal technique. Thereafter the catalysts were assessed for the degradation and mineralization of imidacloprid (IMD). The catalysts were characterized using SEM, BET, XRD, UV-Vis DRS, photoluminescence spectroscopy, and XPS techniques to analyze the various properties for its effectiveness. XRD studies reveals the monoclinic as well as tetragonal phase in synthesized BiVO4 and its composite. In a UV-C light with an intensity of 15 W/m2 and at neutral pH, the degradation rate was significantly higher (94.2%) for BiVO4/g-C3N4 (90:10), denoted as BVCN10, compared to the bare BiVO4 nano-catalyst (83.2%) within a short period of 30 min. BVCN10 catalyst reported higher surface area, improved visible light absorption capacity, and lower electron-hole recombination, presence of monoclinic and tetragonal phases which might have enhanced its photocatalytic activity thereby accelerating degradation efficiency. Kinetic studies show that the degradation of IMD follows the first-order rate law with a rate constant (k) 0.11 min−1. Furthermore, BVCN10 can be used five times without losing catalytic activity, making it a reliable nanocatalyst with economic and environmental benefits.