Degradation Of RhB Research Articles

Ag/α-Fe2O3/g-C3N4 nanocomposites as Z-scheme heterojunction photocatalysts for degradation of RhB

In this study, Ag/α-Fe2O3/g-C3N4 composites with varying α-Fe2O3 and Ag contents were synthesized by loading α-Fe2O3 and Ag nanoparticles onto the g-C3N4 with a high specific surface area via acid annealing. These composites were then utilized for the photocatalytic degradation of RhB under the irradiation of visible light. For α-Fe2O3/g-C3N4 composites with 5 wt% content of α-Fe2O3, the degradation efficiency reached a peak of 97.57% within 55 min, which was much higher than that of α-Fe2O3 and acid-annealed g-C3N4 with 45.92% and 83.61%, respectively. Furthermore, the photocatalytic degradation efficiency of Ag/α-Fe2O3/g-C3N4 composites reached its maximum of 99.61% with 1% content of Ag. It was demonstrated that the ternary Z-scheme heterojunction construction leaded to a significant enhancement of carrier separation and transfer effects, while the incorporation of Ag serves as electron reservoirs and photoinduced electrons capturers, thereby significantly enhancing the Fenton reaction and photocatalytic performance. This work is significant to drive the widespread application of g-C3N4 based heterojunctions in photocatalytic water purification.

Enhanced photocatalytic degradation of organic dyes by carbon quantum dots-ZnFe2O4 composites

To safely cope with the hazardous methylene blue (MB) and rhodamine (RhB) dyes in wastewater, ZnFe2O4 has shown promise as attractive photocatalytic degradation material. Therefore, we synthesized CQDs-decorated ZnFe2O4 microspheres and successfully degraded MB and RhB dyes under UV light. The CQDs/ZnFe2O4 composites exhibited superior performance as compared to pure ZnFe2O4, achieving nearly 100% degradation of MB in 60 min and 95% degradation of RhB in 80 min. Additionally, the CQDs/ZnFe2O4 material was found stable after four consecutive cycles during the photocatalytic activity. Density functional theory calculations revealed that CQDs generated new gap states near the Fermi level, enhancing the charge separation and conductivity of the composites. The photocatalytic mechanism involved the generation of holes, .OH and .O2 radicals as the active species. These results demonstrate that CQDs/ZnFe2O4 composites can be promising candidates in wastewater treatment along with other wide range of applications.

Redeeming the photocatalytic potential of CuWO4 incorporating Ag6Si2O7 via S-scheme PN heterostructure

Water pollution and energy crisis are deemed the most prevalent issues of contemporary decades, and enhanced efforts to counteract these issues via semiconductor photocatalyst engineering are among the best-proposed solutions. Semiconductor photocatalysts could effectively transform clean sunlight into chemical energy, thereby facilitating the breakdown of organic dyes. Herein, we demonstrate the PN heterojunction S scheme photocatalyst Ag6Si2O7/CuWO4 via the facile hydrothermal method. The Ag6Si2O7/CuWO4 heterostructure discerns the broadening of the absorption spectrum and enhanced carrier separation owing to the interfacial process at the interface. Both these aspects work as a stimulus regarding the photocatalytic properties and add versatilities to the effective utilization of carriers. The performance of different ratios of Ag6Si2O7 and CuWO4 in Ag6Si2O7/CuWO4 composite was monitored via photocatalytic degradation of Rhodamine B and Methylene Blue under visible irradiation. About 97.50% degradation efficiency for RhB was reached in 50 minutes at a 1:5 molar ratio (AgCW-E). The degradation constant rate of AgCW-E for RhB and MB was 21.12 and 26.13 times higher than pristine, respectively. Based on trapping experiments and electron spin resonance spectra, it was determined that the photogenerated holes (h+) and •O2- played a crucial role as active species in the photocatalytic degradation of RhB. The synthetic substances additionally demonstrated great promise for recycling. The present study delivers an innovative perspective on developing a more potent Ag6Si2O7/ CuWO4 nano heterojunction photocatalyst that can capture visible light.

Synergistic Enhancement of Carrier Migration by SnO2/ZnO@GO Heterojunction for Rapid Degradation of RhB.

Organic dyes in natural waters jeopardize human health. Whether semiconductor materials can effectively degrade dyes has become a challenge for scientific research. Based on this, this study rationally prepared different nanocomposites to remove organic dyes effectively. Pure SnO2 quantum dots, ZnO nanosheets, and SnO2/ZnO (ZS) binary nanocomposites are prepared using the hydrothermal method. Subsequently, SnO2/ZnO@GO (ZSG) ternary composites containing different amounts of GO, i.e., ZSG-5, ZSG-15, and ZSG-25, are synthesized by an ultrasonic water bath method, in which ZS was coupled with GO to form Z-type heterojunctions. The ZSG-15 ternary composites exhibited excellent photocatalytic activity for the degradation of rhodamine B by simulating sunlight. The test results show that the degradation rate of ZSG-15 is about 7.6 times higher than ZnO. The increase in photocatalytic activity is attributed to the synergistic effect of SnO2 and GO to improve the separation efficiency of photogenerated carriers in ZnO. Notably, the large specific surface area of GO increases the reactive sites. Compared with binary nanocomposites, ZSG-15 broadens the response range to light while further accelerating the electron transport rate and improving the photoelectric stability.

Mechanism analysis of photocatalytic activity on Semiconductor-Type-Modulated heterojunctions

The construction of heterojunction is one of the most popular strategies to improve the performance of photocatalysts, but the influence of heterojunction types on their photocatalytic behaviors is rarely investigated. Here, the p-n and n-n type heterojunctions were constructed through combining p-type BiOBr (p-BOB) or n-type BiOBr (n-BOB) with n-type g-C3N4 (CN), and their photocatalytic performances were evaluated through RhB degradation and production of H2 in comparison with that of pure n-/p- BiOBr semiconductor. The n-n type heterojunction n-BOB/CN exhibits more excellent photocatalytic performance than that of p-n type heterojunction p-BOB/CN though the latter presents more efficient separation of photogenerated carriers with the strongest photocurrent response and the smallest impedance under the driven of strong built-in electric field. The step-scheme (S-scheme) charge transfer mechanism in n-BOB/CN heterojunction was proposed based on the calculation of work functions and the corresponding valance or conduction band potential, which is responsible for the more excellent photocatalytic performance of n-BOB/CN than that of p-BOB/CN.

Facile solvothermal synthesis of CoO/BiOI flower-like nanocomposites for degradation of RhB under visible-light irradiation

Facile solvothermal synthesis of CoO/BiOI flower-like nanocomposites for degradation of RhB under visible-light irradiation

Synergistic enhancement of visible light Photocatalysis: Tailoring dual Z-scheme Fe2O3/C3N4/NH2-MIL-125 ternary composites for organic pollutant degradation

In this study, Fe2O3/C3N4/NH2-MIL-125 ternary composite photocatalysts were synthesized. Their amino groups provided close bonding between these materials, facilitating the effective separation of electrons and holes. Besides, each component of Fe2O3/C3N4/NH2-MIL-125 plays a crucial role. NH2-MIL-125 provided a high surface area, C3N4 contributed to the primary photocatalytic activity, and Fe2O3 aided in enhancing light absorption, generating additional potential to produce hydroxyl radicals, thereby further enhancing photocatalytic activity. Moreover, the proportion of loaded Fe2O3 and C3N4 in the ternary material was investigated. It was found that Fe2O3/C3N4/NH2-MIL-125 with a 1:1 ratio of Fe2O3 and C3N4 (FeCN1:1/NM125) exhibited excellent photocatalytic performance, in which RhB degradation reached 100% under visible light irradiation, conforming to first-order kinetics analysis with a reaction rate constant k of 0.0164 min−1. Its efficiency was twice that of the binary catalyst C3N4/NH2-MIL-125 or Fe2O3/NH2-MIL-125, seven times that of the pristine catalyst C3N4, and ten times that of the pristine catalyst NH2-MIL-125. Scavenger experiments showed that the degradation efficiencies were 52.57%, 55.51%, and 63.41%, respectively, indicating that three active species, namely superoxide radicals, holes, and hydroxyl radicals, made significant contributions to photocatalysis.

CuCo2O4/CF cathode with bifunctional and dual reaction centers exhibits high RhB degradation in electro-Fenton systems

Cobalt-based oxide CuCo2O4-loaded CuCo2O4/carbon felt (CF) composite cathodes were synthesized by hydrothermal deposition of a precursor of Cu/Fe oxides on CF followed by roasting in air. The material serves both catalytic and cathodic dual functions in the heterogeneous electro-Fenton (EF) process. Through XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscope), and catalytic experiments, it was concluded that CuCo2O4 loading was successful and the highest hydrophilic 180-CuCo2O4/CF was obtained by varying the hydrothermal temperature without destroying the original structure. 180-CuCo2O4/CF accomplished 98.03 % degradation in 60 min, and it was found to maintain high degradation capacity in the pH 3 ∼ 9 range in experiments where the experimental parameters were varied. Compared to monometallic oxides, Cu and Co dual active centers are integrated in CuCo2O4, giving it diverse redox properties and oxidation states. As a result, the CuCo2O4/CF material can realize the dual function of catalytic and cathodic, which provides a new development direction in practical wastewater treatment.

Optimization, Kinetics, and Thermodynamics Study on the Degradation of RhB by ZnO Modified with Nitrogen and Sulfur Co-Doped Carbon Quantum Dots

Optimization, Kinetics, and Thermodynamics Study on the Degradation of RhB by ZnO Modified with Nitrogen and Sulfur Co-Doped Carbon Quantum Dots

Ultrathin Layered Structure and Oxygen Vacancies Mediated Efficient Charge Separation toward High Photocatalytic Activity in BiOIO3 Nanosheets.

Previous bismuth-based photocatalysts usually employ a strong acid solution (e.g., HNO3 solution) to obtain an ultrathin structure toward high photocatalytic activity. In this work, the ultrathin layered BiOIO3 nanosheets are successfully synthesized using just the glucose hydrothermal solution. The high-concentration glucose solution shows the obvious acidity after the hydrothermal process, which leads to the quick decrease in thickness of BiOIO3 nanosheets from ∼45.58 to ∼5.74 nm. The ultrathin structure can greatly improve charge carriers' separation and transfer efficiency. The generation of reductive iodide ions brings about oxygen vacancies in the ultrathin nanosheets, then the defect energy level is formed, causing the decreased band gap and improving the visible light absorption. Compared to thick BiOIO3 nanosheet with little oxygen vacancies, much higher carrier separation efficiency and visible light absorption are achieved in the ultrathin nanosheets with oxygen vacancies, resulting in an excellent photocatalytic performance (0.1980 min-1 for RhB degradation), which is much higher than most other bismuth-based photocatalysts. The superoxide radicals (•O2-) and holes (h+) are the major active species responsible for high photocatalytic activity. This work affords an environmentally friendly strategy to synthesize ultrathin photocatalysts with superior photocatalytic properties.

Electron, hole and radical competition mechanism of layered porous g-C3N4 for hydrogen generation and organic pollutant degradation

Halogen doping is an effective approach to regulate the electronic structure and improve photocatalytic properties of g-C3N4. Here, a salt-assisted approach was employed to prepare layered porous halogen-doped g-C3N4. The effects of halogen electronegativity and pore morphology were discussed. Highly electronegative F-doped g-C3N4 with smaller pore size and higher surface area displayed the enhanced absorption property on reactants. The H2 production rate decreased and the RhB degradation significantly increased with increasing the electronegativity of layered porous g-C3N4, which was significantly different from the conventional halogen-doped g-C3N4 prepared with halogenated acid and monolayer g-C3N4. The decreased H2 evolution can be ascribed to the strong adsorption property, and the strong interactions between halide ions and H+ were difficult to be disassociated. Additionally, the RhB degradation performance of halogen-doped g-C3N4 significantly increased with increasing the electronegativity. The most active species that dominated the RhB degradation of F-doped g-C3N4 are leaved holes (h+), which are totally different from that of the pristine g-C3N4 and Cl/Br-doped g-C3N4 (superoxide radicals,·O2–). This work helps us to well understand the role and importance of electronegativity and pore morphology on the H2 generation and RhB degradation properties of layered porous g-C3N4.

Efficient degradation of rhodamine B by MoS2 modified Co-MOF derived nitrogen-doped carbon activated peroxymonosulfate

How to improve the issues of ion agglomeration and metal ion leaching, and how to prepare cobalt-based catalysts with high reactivity and stability, are highly desired yet challenging. In this paper, MoS2 modified Co-MOF derived nitrogen-doped carbon (Co/PCN/MoS2) microspheres rich in active sites were prepared using a simple carbonation-hydrothermal method, with g-C3N4, MoS2 and Co-MOF to overcome the aforementioned limitations. The flower-like nanostructure of MoS2 contributed to exposing more marginal active sites, allowing the high dispersion of Co-MOF within its structure. Meanwhile, Mo4+/Mo6+ and S species coexisted in MoS2, which promoted the valence cycle and electron transfer process, and improved the catalytic activity of the composite. The successful synthesis of Co/PCN/MoS2 was proved by XRD, SEM and FTIR characterizations. The electrochemical performance analysis showed that Co/PCN/MoS2 exhibited higher redox capacity than MoS2, and Co/PCN/MoS2/PMS system achieved the degradation rate of RhB as high as 97.19% within 30 min, which is higher than that of Co-MOF/g-C3N4/PMS (80.67%), Co-MOF/MoS2/PMS (78.08%), Co-MOF/PMS (77.00%), g-C3N4/PMS (53.68%) and MoS2/PMS (28.10%) systems. It had good anti-interference ability against coexisting substances, achieved good degradation performance in a wide pH range (pH 2.0–10.0), and possessed excellent stability and reusability with RhB degradation rate of 91.10% after 5 cycles. The quenching test confirmed that non free radical 1O2 is the main ROS for RhB degradation. This work is expected to provide a new idea and direction for the design and development of metal-doped heterogeneous catalysts with high activity and stability.

Construction of core-shell magnetic metal-organic framework composites Fe3O4@MIL-101(Fe, Co) for degradation of RhB by efficiently activating PMS.

Low catalytic efficiency and catalyst recovery are the key factors limiting the practical application of advanced oxidation processes. In this work, a core-shell magnetic nanostructure Fe3O4@MIL-101(Fe, Co) was prepared via a simple solvothermal method. The core-shell structure and magnetic recovery performance were characterized by various technologies. The results of dye degradation experiments proved that within 10 minutes, the Fe3O4@MIL-101(Fe, Co)/PMS system can degrade more than 95% of 10 mg per L Rhodamine (RhB) at an initial pH of 7, which possesses higher catalytic activity than the Fe3O4/PMS system and the MIL-101(Fe, Co)/PMS system. The effects of initial solution pH and coexisting anions in water on the degradation of RhB were further discussed. The results showed that Fe3O4@MIL-101(Fe, Co) displayed excellent degradation efficiency in a wide pH range of 3-11 and capability of resisting coexisting anions. It is worth mentioning that after five cycles, the RhB removal rate can still be maintained at over 90% after 10 minutes of reaction. Free radical quenching experiments were further studied, confirming that ˙OH and SO4-˙ were involved in the degradation of RhB, while the dominating active free radical was SO4-˙. The possible reaction mechanism of the RhB degradation process was also inferred.

Intense interaction between biochar/g-C3N4 promotes the photocatalytic performance of heterojunction catalysts.

In recent decades, environmental protection and energy issues have gained significant attention, and the development of efficient, environmentally friendly catalysts has become especially crucial for the advancement of photocatalytic technology. This study employs the sintering method to produce biochar. A hybrid photocatalyst for the degradation of RHB under visible light was prepared by loading varying proportions of biochar onto g-C3N4 using ultrasonic technology. Among them, 2% CGCD (2% biochar/g-C3N4) achieved a degradation rate of 91.3% for RHB after 30 minutes of visible light exposure, which was more than 25% higher than GCD (g-C3N4), and exhibited a higher photocurrent intensity and lower impedance value. The enhancement in photocatalytic activity is primarily attributed to the increased utilization efficiency of visible light and the electron transfer channel effect from a minor amount of biochar, effectively reducing the recombination of photo-generated charge carriers on the g-C3N4 surface, thereby significantly improving photocatalytic activity. The degradation of RHB is synergistically mediated by O2 -, h+ (photo-generated holes), and ˙OH. The free radical capture experiment indicates that O2 - and ˙OH are the primary active components, followed by h+.

Organic pollutant degradation for micro-molecule product emission over SiO2 layers-coated g-C3N4 photocatalysts.

In this study, a SiO2 layer-coated g-C3N4 catalyst was prepared by a sol-gel method to overcome the poor adsorption ability and high recombination rate of charge carriers of pristine g-C3N4. SEM and TEM images indicated that SiO2 nanoparticles were coated on the surface of g-C3N4 nanoparticles with a layered structure and the layers were tightly contacted with g-C3N4. XRD patterns, FTIR spectra, UV-vis spectra and XPS spectra revealed that the structure of g-C3N4 was not destroyed and its photoelectric catalytic properties were not suppressed by the coating of SiO2 layers. Adsorption experiments revealed that the SiO2 layers improved the adsorption performance of g-C3N4 and their ratios were adjusted. The molecular weights of the final products of the degradation of RhB and antibiotics were at the micro-molecule level while the amount of g-C3N4 reached 1.2% of the mass fraction, which were more suitable for pollutant degradation compared with those of g-C3N4 due to its poor adsorption ability. The reason for this was likely that the SiO2 layers were not only beneficial for the adsorption of pollutants and intermediate products but also for prolonging the life time of the separated electrons and holes. Finally, active trapping experiments confirmed that both the holes and superoxide radicals were the main factors in the degradation of RhB and antibiotics, with the superoxides being the most active species.

Simultaneous enhancement of the optical absorption, ferroelectric polarization, and photocatalytic activity by designing the Ti/Fe ratio for Bi5Ti3FeO15

Bismuth-contained Aurivillius compounds are potentially low-cost and eco-friendly photocatalysts for organic pollutant degradation because of their unique layered crystal structure. Bi5Ti3-xFe1+xO15 (BTF-x, x = 0–1) photocatalysts were synthesized through the molten salt method. The crystal structure was determined by XRD Rietveld refinements. The phase constitution was found to change from a single 4-layered Aurivillius phase for x = 0 to mixed Aurivillius phases with different layer numbers as x increases. BTF-0.8 and BTF-1 exhibit better frequency stability of dielectric properties. The decrease in the Ti/Fe ratio leads to a monotonic reduction of the bandgap, ascribed to the increase in the octahedral distortion rather than the oxygen vacancy concentration. Surprisingly, the ferroelectric polarization is also improved by decreasing the Ti/Fe ratio and the best ferroelectricity was obtained in BTF-1. The photocatalytic activity of BTF-x catalysts was examined by RhB degradation under visible-light irradiation. The decrease in the Ti/Fe ratio also enhances the photocatalytic activity of BTF-x catalysts. The fastest photodegradation rate was obtained in BTF-1, about 9 times higher than that of BTF-0. Scavenger test studies confirmed that the level of contribution to RhB photodegradation was h+, O2•−, and •OH radicals in descending order. Furthermore, the excellent stability and reusability of BTF-x catalysts were demonstrated by the photocatalytic cycle tests. All the results suggested without introducing hetero elements, adjusting the Ti/Fe ratio was an effective means to narrow the bandgap, improve the ferroelectricity and enhance the photocatalytic activity simultaneously. We hope the present study can be generalized to other Aurivillius phases to acquire much better performance and broader application.

Photocatalytic degradation of RhB in wastewater by zinc ion-doped Bi5O7I

Bi5O7I doped with Zn2+ (Zn2+/Bi5O7I) was prepared using a precipitation calcination method.

A novel layered double hydroxide-based ternary nanocomposite for the effective photocatalytic degradation of rhodamine B.

Photocatalytic degradation of organic pollutants is a green and effective route of wastewater treatment. Zinc oxide was initially used for this purpose; however, calcined zinc/chromium layered double hydroxide (ZnCr-LDO) and cadmium sulfide quantum dots (CdSQDs)-based nanocomposites proved as superior alternatives. Herein, we report a green sonochemical method for the sol-gel fabrication of novel CdSQDs@ZnCr-LDO/ZnO ternary nanocomposite that exhibited exceptional photocatalytic activity for the degradation of rhodamine B dye (RhB), in wastewaters, under UV-A-irradiation. The features of the ternary nanocomposite were investigated using various physicochemical techniques, including XRD, SEM, TEM, EDX, XPS, BET, zeta potential, DRS, and PL measurements. The RhB dye % removal was 38.02, 40.2, and 98% using pristine ZnO, ZnCr-LDO and the ternary CdSQDs@ZnCr-LDO/ZnO-based nanomaterials, respectively, reflecting the superior ternary nanocomposite's photocatalytic activity that made it an excellent competitor to commonly reported photocatalysts. Additionally, an investigation was carried out to determine the key reactive species in the photocatalytic degradation of RhB, considering both scavenger's type and concentration. The prevailing mechanism was found to be the reductive photodegradation pathway. Furthermore, several models were utilized to describe the kinetics of photocatalytic performance of the ternary nanocomposite and a typical Z-scheme type-II photocatalytic heterojunction mechanism was inferred.

Bi-doped BaBiO3 (x = 0%, 5%, 10%, 15%, and 20%) perovskite oxides by a sol-gel method: comprehensive biological assessment and RhB photodegradation.

The BaBiO3 (BBO) perovskite oxide was prepared via a sol-gel method with different concentrations of Bi nitrate and examined as a photocatalyst for RhB degradation under sunlight, and its antioxidant and antibacterial activities were examined. X-ray diffraction (XRD) indicated the formation of a BaBiO3-BaCO3 (BBO-BCO) binary composite. For the degradation of RhB under solar radiation, high photocatalytic activity (73%) was observed. According to the antibacterial activity study, the addition of Bi enhanced the antibacterial activity of the resulting material against both Gram-positive and Gram-negative microorganisms. The Bi%-BBO (Bi 20%) inhibited 96.23% S. aureus. 10% Bi-BBO as an antioxidant agent had the most efficacious IC50 value of 2.50 mg mL-1. These results seem to suggest that BBO-BCO is a promising catalytic material with potential application in the fields of catalysis and medicine.

Design of interfacial dual Schottky junctions to modulate charge transfer for enhanced piezo-assisted photocatalytic degradation RhB performances

Construction of piezo-assisted interfacial dual Schottky junction to regulate charge transfer and surface reaction rate for the photocatalytic degradation of RhB.