Simulated Visible Light Irradiation Research Articles

Reconstruction of the surface Bi3+ oxide layer on Bi2O2CO3: Facilitating electron transfer for enhanced photocatalytic degradation performance of antibiotics in water

The advancement and meticulous design of functional photocatalysts exhibiting exceptional photocatalytic redox activity represent a pivotal approach to mitigating the dual challenges of environmental pollution and energy scarcity. In this study, we elucidate the construction of a Bi2O2CO3 catalytic system capable of inhibiting oxidative electron transfer through the attenuation of homogeneous Bi0 particle formation, achieved through the judicious modulation of solvent ratios. This innovative architecture possesses a distinctive active site and enhances interfacial Bi-O electron transfer pathways via exposure to oxidized Bi3+. Upon photoexcitation, the Bi2O2CO3 catalytic system undergoes structural distortions in its excited state that facilitate forbidden radiative relaxation, thereby fostering long-lived charge separation states. Remarkable catalytic activity was demonstrated in the remediation of pollutants, encompassing auto-oxidation and the catalytic degradation of superoxide radicals (•O2−) and holes (h+). Notably, the effective degradation of tetracycline hydrochloride (TCH) in aqueous media reached an impressive 86 % under simulated visible light irradiation, accompanied by a reaction rate constant 3.08 times superior to that of the 5-Bi/Bi2O2CO3 counterpart. Theoretical analyses revealed that the oxidized state of Bi2O2CO3 exhibits a crystal structure with significant electron trapping capability, undergoing pronounced apparent relaxation phenomena on its surface while demonstrating an enhanced adsorption affinity for H2O and O2. The potential degradation mechanisms were rigorously investigated through High-performance liquid chromatography (HPLC-MS), elucidating the photodegradation pathways and intermediates of TC. This work may serve as a distinct paradigm for the rational design of novel photocatalysts aimed at fostering sustainable environmental remediation and advancing energy innovation.

Controllable preparation of red phosphorus nanoribbons for enhanced photocatalytic degradation of Methyl Orange and Tetracycline.

Nanoribbons (NRs), leveraging the flexibility of one-dimensional materials and the expansive surface area of two-dimensional materials, offer heightened exposure to edge sites and superior charge transfer rates. Consequently, they present promising prospects within the domain of photocatalysis. Crystalline red phosphorus (cRP), dcharacterized by its layered and fibrous structure, lends itself readily to the production of nanoribbons. Our study demonstrates a robust method for achieving high-yield, high-quality cRP by concurrently introducing mineralizing agent I2 and Si wafers into the Chemical Vapor Transport (CVT) synthesis process. Through ultrasound assistance, we transformed high-quality cRP into crystalline red phosphorus nanoribbons (cRP NRs) with an average thickness ranging from 7.5 to 17.5nm and an average width between 75 and 175nm. cRP NRs (I2 and Si) showcased impressive degradation capabilities towards Methyl Orange (MO) and Tetracycline (TC), achieving a remarkable 99% degradation of MO within 18min under the simulated visible-light irradiation. The reactive species capturing experiments confirmed that ·O2- was the primary active agent responsible for the photocatalytic degradation of MO.

Construction of La1−xSrxNiO3/g-C3N4 type-Z heterojunctions with enhanced visible-light photocatalytic degradation of organic pollutants

Lanthanum nickelate (LaNiO3), known for its high visible-light absorption, is a promising photocatalyst for water purification. However, the low conduction band position and high photogenerated carrier complexation rate of pure LaNiO3 limit its photocatalytic activity. To address this issue, we investigated the synergistic effects of doping and constructing heterojunctions. A La0.9Sr0.1NiO3 (20%)/g-C3N4 (L2CN8) heterojunction was successfully created. In addition, various characterisation techniques were then employed to analyse the structure–performance relationships of these heterojunction photocatalysts in degrading organic dyes. Results revealed that at a 10% Sr doping level, the oxygen vacancy content was 0.68, which is significantly higher than that of LaNiO3 (0.05). The increased number of oxygen vacancies enhanced the electron capture ability and improved the separation efficiency of photogenerated carriers. Furthermore, the optimised L2CN8 (20 mg) achieved 81.2% and 73.8% removal of methylene blue (50.0 mL, 10 mg L−1) and tetracycline (50.0 mL, 10 mg L−1) under simulated visible-light irradiation (λ > 420 nm). Furthermore, an active species capture experiment confirmed the significant role of superoxide radicals (·O2−) in the degradation process. Based on these experimental findings, we proposed a rational Z-type charge transfer mechanism. This study holds great importance for water pollution control and environmental protection.

Hydrogel composites based on chitosan and CuAuTiO2 photocatalysts for hydrogen production under simulated sunlight irradiation

This study explored the photocatalytic hydrogen evolution reaction (HER) using novel biohydrogel composites comprising chitosan, and a photocatalyst consisting in TiO2 P25 decorated with Au and/or Cu mono- and bimetallic nanoparticles (NPs) to boost its optical and catalytic properties. Low loads of Cu and Au (1 mol%) were incorporated onto TiO2 via a green photodeposition methodology. Characterization techniques confirmed the incorporation of decoration metals as well as improvements in the light absorption properties in the visible light interval (λ > 390 nm) and electron transfer capability of the semiconductors. Thereafter, Au and/or Cu NP-supported TiO2 were incorporated into chitosan-based physically crosslinked hydrogels revealing significant interactions between chitosan functional groups (hydroxyls, amines and amides) with the NPs to ensure its encapsulation. These materials were evaluated as photocatalysts for the HER using water and methanol mixtures under simulated sunlight and visible light irradiation. Sample CuAuTiO2/ChTPP exhibited a maximum hydrogen generation of 1790 μmol g−1 h−1 under simulated sunlight irradiation, almost 12-folds higher compared with TiO2/ChTPP. Also, the nanocomposites revealed a similar tendency under visible light with a maximum hydrogen production of 590 μmol g−1 h−1. These results agree with the efficiency of photoinduced charge separation revealed by transient photocurrent and EIS.

Effect of Fe doping on crystalline phase, structure and photocatalytic properties of TiO2 thin films

Undoped and Fe-doped TiO2 thin films were fabricated on Si substrates using sol-gel method. XRD and Rietveld refinement results show the anatase to rutile transition in the system. SEM and AFM spectra demonstrate that the generation of agglomeration phenomena after Fe doping provides the nucleation point for the phase transition, and the difference in the Gibbs free energies of the two phases provides the driving force for the phase transition. XPS measurements verify that the formation of oxides after Fe doping contributes to the surface thermodynamic equilibrium and the possibility of the surface atomic rearrangements during the anatase to rutile phase transition. The energy band diagram illustrates at the level of electronic structure that the phase transition raises the position of the conduction band minimum of the film and the oxide of Fe that is formed becomes the charge complex center. Finally, the results of degradation of methylene blue solution under simulated visible light irradiation show that Fe doping reduces the photocatalytic ability of TiO2 films. The corresponding mechanism is proposed to explain the photocatalytic activity by which Fe3+ of larger radius replaces Ti4+ to promote the transition of the film from anatase to rutile and to act as a charge complex center.

Investigation on visible-light induced photocatalytic activity for pure, Ce:doped TiO2 and B:Ce co-doped TiO2 catalysts

In this study, the photocatalytic activity of pristine and Boron (B) - Cerium (Ce) co-doped titanium dioxide (TiO2) have been investigated towards the degradation of aqueous solution of Methylene Blue (MB) dye under visible light activity. The B:Ce co-doped TiO2 catalyst was successfully prepared by co-precipitation method. The structural, optical, and morphological properties of the synthesized samples were characterized by different techniques. PXRD analysis revealed that the prepared nanoparticles (NPs) have tetragonal crystal structures with an anatase phase. In FESEM analysis, the different morphologies (spherical and nanorod bundles) were observed from the synthesized Pure, Ce:TiO2 and B:Ce co-doped TiO2 NPs. The UV-Vis DRS and PL studies showed that B:Ce doped TiO2 exhibited enhanced visible light absorption activity and less electron-hole pair recombination rate. The findings demonstrated the incorporation of B and Ce ions into the TiO2 lattice, which can increase the absorption region to visible light and prevent the recombination rate of e-/h+ pairs. The results of the photocatalytic experiment show that B-Ce co-doped TiO2 improves photodegradation performance, with 97%, 98.0%, and 99% of the MB dye decomposing within 150 min of illumination under simulated visible light irradiation.

Modulation of Fe–MOF via second-transition metal ion doping (Ti, Mn, Zn, Cu) for efficient visible-light driven CO2 reduction to CH4

This study developed metal–organic frameworks (MOFs) with enhanced properties for CO2 conversion by doping second- transition metal ions (Ti, Mn, Zn, and Cu) into Fe–MOF, which resulted in Fe-M−MOF (M = Ti, Mn, Zn, or Cu). The selection of different metal species in the metal cluster nodes of the MOFs significantly impacted the CO2 conversion efficiency. Among the different combinations, the Fe–Cu bimetallic cluster node was identified as the most optimal node. In addition, we investigated various variables and preparation conditions for determining the optimal synthesis conditions for Fe–Cu-MOFs. We observed that a synthesis temperature, time, and pH of 130 °C, 15 h, and 3.2, respectively, yielded the best results. The 13CO2 isotope labeling method confirmed that the carbon source of CO and CH4 were derived from CO2. Under simulated visible-light irradiation (λ ≥ 420 nm), Fe–Cu-T130 exhibited the highest photocatalytic activity, with a CH4 generation rate of up to 444.2 μmol g−1 h−1. This high activity was attributed to several factors. First, the presence of Fe2+, Fe3+, and Cu2+ on the surface of Fe–Cu-T130 resulted in photogenerated electrons and holes under visible-light excitation. Fe2+ accepted electrons to reduce CO2, whereas Fe3+ and Cu2+ oxidized H2O through holes. Second, the polycrystalline structure of Fe–Cu-T130 with abundant surface oxygen vacancies enhanced the chemical reactivity. Finally, the low conduction band position and narrower bandgap of Fe–Cu-T130 facilitated the excitation of electrons into the conduction band, thereby promoting the CO2 reduction reaction. This study successfully demonstrated the enhanced photocatalytic activity of Fe–Cu-T130 for CO2 conversion under visible light. The findings provide insight into the development of MOFs with improved properties for the sustainable and efficient utilization of CO2.

Enhanced photocatalytic CO2 reduction by integrating an iron based metal-organic framework and a photosensitizer

The conversion of CO2 into fuels via photoreduction is a promising method to reduce environmental pollution and alleviate the energy crisis. Herein, we report iron-based metal-organic frameworks (Fe-MOFs) that can host a photosensitizer Ru(dcbpy)3Cl2 (PS) to form a range of photocatalytic systems, PS-Fe-MOFs, that are capable of increasing the activity of CO2 conversion. Among the four Fe-MOFs and PS composites, PSMIL-101(Fe) showed the highest activity for photocatalytic CO2 reduction under simulated visible light irradiation (yielding CO and CH4 at 116.7 and 79.1 μmol·g−1 within 5 h, respectively), approximately 13 times higher than that of pristine MIL-101(Fe). In situ FTIR spectra and theoretical calculations further elucidated the coexistence of CO and CH4 as the products of CO2 reduction by PSMIL-101(Fe). Additionally, the optical and electrochemical experiments, alongside theoretical calculations, indicated that PS bound on the surface of the Fe-MOFs provided a greater charge transfer efficiency, thus leading to a high photocatalytic CO2 reduction activity.

Interfacial chemical bond and oxygen vacancies modulated Mo2S3/BiOBr high-low junctions for enhanced photocatalysis gatifloxacin degradation

Insufficient light absorption and rapid recombination of photogenerated charges are considered to be the main obstacles limiting the efficiency of photocatalytic degradation of organic pollutants. In this study, a novel Mo2S3/BiOBr high-low junction was constructed by coupling narrow bandgap Mo2S3 to improve the light absorption capacity of BiOBr and enhance the utilization of photogenerated charges. Under simulated visible light irradiation, the optimised Mo2S3/BiOBr-6% high-low junction (90.1%) exhibited higher degradation efficiency of gatifloxacin compared to BiOBr (74.9%) and Mo2S3 (72.4%). The improved photocatalytic activity is mainly attributed to the interfacial chemical bonding and the formation of high-low junctions facilitating the rapid transfer of photogenerated charges between semiconductors, resulting in effective separation of photogenerated charges. In addition, the abundant oxygen vacancies in Mo2S3/BiOBr can act as electron traps to trap electrons and effectively reduce the photogenerated charge complexation. This study provides new perspectives for the construction of high-low junctions with interfacial chemical bonds and abundant oxygen vacancies and their use in the photocatalytic degradation of organic pollutants.

Chitosan and TiO2 functionalized polypropylene nonwoven fabrics with visible light induced photocatalytic antibacterial performances

Chitosan/TiO2 functionalized polypropylene (CS/TiO2/PP) nonwoven fabrics were fabricated through crosslinking of chitosan with glutaraldehyde followed by loading of TiO2 nanoparticles. The functionalized CS/TiO2/PP has super hydrophilicity and excellent visible light induced photocatalytic antibacterial properties owing to the synergistic effects of CS and TiO2. The photocatalytic degradation performance was determined by assessing the degradation of methyl blue under simulated visible light irradiation and its recyclability was also evaluated. In addition, SEM images demonstrated that TiO2 nanoparticles were distributed evenly on the surface of the 2 g/L CS/TiO2/PP. Meanwhile, the polypropylene surface showed a significant increase in hydrophilicity after being treated with chitosan and TiO2. The photocatalytic degradation results revealed that CS/TiO2/PP had higher photocatalytic properties than those of pure PP under visible light, and the degradation rate of methylene blue reached 96.4 % after 90 min of light exposure. Compared to pure PP, the antibacterial properties of CS/TiO2/PP significantly increased, and the bacterial reduction percentages were increased to 98.7 % and 96.3 %, against E. coli and S. aureus, respectively. The functionalized CS/TiO2/PP composites exhibited promising potential in environmentally friendly antibacterial materials.

Ternary rGO decorated W18O49 @g-C3N4 composite as a full-spectrum-responded Z-scheme photocatalyst for efficient photocatalytic H2O2 production and water disinfection

Integrating g-C3N4 with narrow-band semiconductor to construct a Z-scheme structured heterojunction has been regarded as a common strategy to improve the photocatalytic performance of g-C3N4. However, limited catalytic activity increment is achieved due to the contradiction of expanding the light absorption scope of traditional photo-oxidation semiconductors (PS II) and preserving their valance band oxidative abilities. Herein, to extend the light absorption range of g-C3N4 based Z-scheme photocatalyst to the whole solar spectra while without losing the high oxidative ability of this system, we select the heavy doped W18O49 as PS II and provide a facile in situ hydrothermal method to elaborately fabricate an rGO decorated W18O49 @g-C3N4 (r-CNW) Z-scheme photocatalyst. The prepared r-CNW-2 (with optimal W18O49 to g-C3N4 weight ratio of 1:2) exhibits improved photocatalytic performance with H2O2 generation rates of 71, 58.5 and 6.3 μmol g−1 h−1 obtained under the simulated solar light, visible light (>400 nm) and NIR light (>800 nm) irradiation, respectively, which is 1.3 and 2 times higher than those of the g-C3N4 counterparts (54, 29 μmol g−1 h−1 and even not detected).such outstanding performance of r-CNW-2 could be associated with the broader light absorption, fast charge separation, and rapid redox reactions. Moreover, the r-CNW-2 also displays an excellent E-coli inactivation activity, comparable to most g-C3N4-based photocatalysts. Our work gives a new insight through trading off light absorption and redox ability to fabricate efficient Z-scheme photocatalyst for photocatalytic H2O2 generation and environmental remediation.

Manganese-Based Metal-Organic Frameworks Photocatalysts for Visible Light-Driven Oxidative Coupling of Benzylamine under Atmospheric Oxygen: A Comparative Study

Research on the utilization of sustainable and renewable energy sources has increased as a result of the world’s expanding energy demand. In this regard, we report the photocatalytic performance of two synthesized Mn-MOFs: MnII3(tp)6/2(bpy)2.(dmf) (C47H35Mn3N5O13) and Mn2(tpa)2(dmf)2 (C22H22Mn2N2O10). The two MOFs were characterized using different spectroscopic and analytical techniques: powder X-ray diffraction, thermogravimetric analysis, diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. MnII3(tp)6/2(bpy)2.(dmf) possesses a band gap value of 2.5 eV, which exhibits significant photocatalytic activity when exposed to simulated visible light irradiation. Mn2(tpa)2(dmf)2 shows a larger band gap of 3.16 eV, which renders the photocatalytic performance under visible light. The oxidation of benzylamine to N,N-benzylidenebenzylamine by a photocatalytic reaction was selected to evaluate the photocatalytic activities of MnII3(tp)6/2(bpy)2.(dmf) and Mn2(tpa)2(dmf)2 in the visible region. In addition to its high photocatalytic performance, MnII3(tp)6/2(bpy)2.(dmf) also showed high thermal stability up to 430 °C. Accordingly, the strategy of designing frameworks possessing mixed ligands provides stability to the frameworks as well as enhancing the photocatalytic performance of frameworks containing bipyridine ligands such as MnII3(tp)6/2(bpy)2.(dmf).

Superior photocatalytic performance and photo disinfection of bacteria of solvothermally synthesized mesoporous La-doped CeO2 under simulated visible light irradiation for wastewater treatment

A simple, cost-effective, and facile solvothermal approach has been adopted to synthesize mesoporous CeO2 nanostructures with varying La-doping (2, 4, and 6 mol%) concentrations. Photocatalytic and antibacterial performances are investigated against the inactivation of Escherichia coli and Bacillus licheniformis bacteria cells. Structural and microstructural characterizations of La-doped CeO2 nanostructures are performed by analyzing X-ray diffraction (XRD) data employing the Rietveld refinement method, scanning electron (SEM) and transmission electron microscopy (TEM) images, Brunauer–Emmett–Teller (BET), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) spectra. Among three doped samples, the 4 mol% La-doped CeO2 (LCe4) has exhibited high oxygen and Ce3+ concentrations, high microstrain, small crystallite size, and lowest band gap energy, as are revealed by the analysis of XPS, UV–VIS absorption spectra, photoluminescence (PL) spectra, and Rietveld refinement result. The LCe4 sample with the highest number of oxygen vacancies and high surface area shows superior photocatalytic activity (∼95% Rhodamin B (RhB) degradation in 130 min, ∼70% Methylene Blue (MB) degradation within 30 min, and ∼95% phenol degradation in 180 min under solar radiation). It shows a striking photo-disinfection effect and enhanced antibacterial activity (almost identical to a pure drug) against gram-positive and gram-negative bacteria under visible light irradiation. This novel disinfection and catalytic property of the LCe4 sample is attributed to the mesoporous structure of materials and surface activity, which lowers the electron-hole recombination rate and transports more photogenerated electrons and holes. The nanostructured mesoporous LCe4 material has been used as an effective visible light-activated photocatalyst and photo disinfection for treating wastewater containing organic dyes and gram-negative and gram-positive bacteria.

Preparation of a high-efficiency low-toxicity CdS/C60 bactericide and investigation of the mechanism.

Photocatalysis is considered as a promising technology to solve bacterial contamination, but the development of efficient photocatalysts with a strong generalizable light response remains a challenge. CdS has a suitable energy gap and good response to visible light, but the photogenerated carrier separation efficiency is low, and the photo-corrosion phenomenon leads to the significant release of Cd2+. In this paper, the CdS/C60 composite photocatalyst bactericide is synthesized via a simple one-step hydrothermal method. Testing via EIS, I-t, PL, and TRPL show that the C60 in the composite improves the hole-electron separation efficiency of CdS, resulting in a better photocatalytic performance. The complete inactivation of S. aureus and E. coli can be achieved within 40 min and 120 min, respectively, by dispersing 100 μg mL-1 of CdS/C60-2 in a diluted bacterial solution under simulated visible-light irradiation. Combined with ESR, SEM, fluorescence staining, DNA gel electrophoresis and ICP technology, it is believed that the high inactivation of bacteria is attributed to the ROS produced during the photocatalytic process, which destroy the integrity of the bacterial cell membrane and further destroy the DNA inside the bacteria, thus causing bacterial inactivation, rather than the inactivation being caused by Cd2+ toxicity.

Enhancement of photocatalytic activities of ZnFe2O4 composite by incorporating halloysite nanotubes for effective elimination of aqueous organic pollutants.

ZnFe2O4 is a highly desirable catalyst due to its exceptional photo-response in the visible light region, but various drawbacks, such as rapid recombination of photo-generated electron-hole pairs and severe particle agglomeration, make it difficult to use. In this study, a co-precipitation approach was used to create ZnFe2O4/HNT (ZF/HNTs) composites. XRD, SEM, TEM, FTIR, BET, and DRS were used to characterize the ZF/HNT composites. Furthermore, the effectiveness of removing crystal violet under simulated visible light irradiation was used to assess photocatalytic activity. The results showed that ZnFe2O4 with typical diameters of around 20nm was significantly distributed on halloysite nanotubes. Because of the synergistic impact of the improved agglomeration phenomena of ZnFe2O4 and the decreased recombination rate of photo-generated electrons and holes, all of the composites had superior photocatalytic performance than pure ZnFe2O4. The ZF/HNTs-11 composite exhibited the highest removal performance, removing 96.7% of the sample in less than 150min. In addition, the composite was very stable and reusable. Consequently, ZF/HNTs-11 composite is an effective catalyst for treating pollutants found in wastewater.

Facile synthesis of N-doped biphasic TiO2 nanoparticles with enhanced visible light-driven photocatalytic performance

Undoped and N-doped TiO2 anatase/brookite mixed-phase nanoparticles were synthesized via a facile sol-gel method using urea as a nitrogen source. Surprisingly, nitrogen played a dual role in doping and controlling the anatase and brookite phases in the nanoparticles. The as-synthesized photocatalysts were characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis and UV–vis diffuse reflectance spectroscopy (DRS). PXRD results revealed that TiO2 nanoparticles consisted of a mixture of anatase and brookite crystalline phases where the anatase phase increased with increasing urea concentration (1–60 wt. %), and the pure anatase phase was found at a urea concentration of ≥15 wt. %. N-doped anatase/brookite mixed-phase (brookite ̴ 20 wt. %) nanoparticles exhibited superior photocatalytic activity over others in degrading rhodamine-B (RhB) under simulated visible light irradiation, and its photocatalytic performance was comparable to that of Degussa P25. The enhanced photodegradation activity was credited to biphasic composition, narrower bandgap energy, and stronger light absorption in the visible region.

Supramolecular nanoarchitectonics with TPPS porphyrin as a fluorescent probe for detection of aminoglycoside antibiotics and their photocatalytic applications for the degradation of rhodamine B dye

The meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) porphyrin was successfully synthesized and applied as a selective turn-off sensor for detecting neomycin and gentamicin antibiotics in aqueous media. The sensing ability of TPPS porphyrin was studied by naked-eye detection as well as UV–vis absorption and fluorescence spectroscopy. The emission intensity of TPPS porphyrin was observed to be decreased dramatically upon addition of neomycin and gentamicin antibiotics. The quantum yield of TPPS porphyrin (56%) which decreases to 2% and 9% upon addition of neomycin and gentamycin, respectively. The quenching efficiency of neomycin and gentamicin towards the TPPS porphyrin was 99.13% and 96% respectively. The detection limit was calculated to be 7.5 × 108 M and 1.1 × 107 M for gentamicin and neomycin respectively, indicating both the antibiotics exhibited efficient quenching abilities. Moreover, the self-assembly of TPPS porphyrin with gentamicin antibiotic have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and FTIR spectroscopy. Interestingly, TPPS porphyrin with 0–10 equiv. of gentamicin, produces nanorod-like structures. The key driving force for the formation of self-assembled nanostructure of TPPS porphyrin with gentamicin is H-bonding between sulfonate group of TPPS and –NH2 and –OH group of gentamicin. The-self-assembled nanostructure exhibited band gap energy in the range of 2.7 to 3 eV. Therefore, these nanostructures were used as a photocatalyst for degradation of RhB dye. Interestingly, nanostructure obtained from 1:2 equiv. of TPPS: gentamicin showed excellent photocatalytic performance, degraded almost 100% of RhB dye in aqueous media within 240 min. with simulated visible light irradiation with rate constant of 2 × 10−2 min−1. A possible mechanism for the photodegradation of RhB using nanorod like structure is also discussed.

Visible-Light-Driven Photocatalytic Coupling of Neat Benzylamine over a Bi-Ellagate Metal-Organic Framework.

Selective aerobic oxidation of benzylamine to N,N-benzylidenebenzylamine was achieved using a bismuth ellagate (Bi-ellagate) metal–organic framework (MOF) under simulated visible light irradiation. The bismuth ellagate photocatalyst was characterized using several spectroscopic techniques: powder X-ray diffraction (PXRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and nitrogen sorption measurements. Product formation was confirmed using 1H-NMR, 13C-NMR, and FTIR. The photocatalytic performance of Bi-ellagate was studied for the first time, which exhibits a band gap value of 2.62 eV, endowing it with a high photocatalytic activity under visible light irradiation. The reaction product, N,N-benzylidenebenzylamine, was selectively obtained with a high conversion yield of ∼96% under solvent-free conditions compared to other control experiments. The Bi-ellagate photocatalyst was recovered and reused four times without any significant loss in its activity, which provides an eco-friendly, low-cost, recyclable, and efficient photocatalyst for potential photocatalytic applications.

Insight into the Novel Z-Scheme ZIF67/WO3 Heterostructure for Improved Photocatalytic Degradation of Methylene Blue Under Visible Light

In this work, a novel Z-scheme heterojunction of ZIF67/WO3 nanocomposite is successfully prepared via immobilizing WO3 on the MOFs ZIF67 and confirmed by measuring XRD, FT-IR spectroscopy, XPS, SEM, TEM, and EDS. UV–vis and Mott-Schottky measurements. The photocatalytic activity of the as-prepared ZIF67/WO3 is evaluated by degrading methylene blue (MB) solution under simulated visible light irradiation. Obviously, the optimal ZIF67/WO3-0.3 (designated as 0.3 g addition of WO3) delivers significant photocatalytic degradation exceeding 90% toward MB within 120 min, which is about 3.0 and 4.2 times higher than those of pure ZIF67 (30.0%) and WO3 (21.2%). With the addition of 0.02 g ZIF67/WO3-0.3 composite, a total volume of 50 mL of MB at 10 mg/L was thoroughly degraded in 120 min with an apparent rate constant of 0.0184 min−1. Reactive species scavenging experiments indicated that the holes (h+) and hydroxyl radical (·OH) are mainly responsible for MB degradation. Moreover, the probable reaction mechanism is elucidated by detecting the intermediates by performing LC–MS measurements. The excellent photocatalytic performance of the ZIF67/WO3 is predominantly determined by the structural properties of the composite and the Z-scheme charge transfer pathway, which promote the efficient separation of photogenerated carriers and facilitate the transfer of photogenerated electrons to active sites. Therefore, it is a promising strategy for immobilizing the WO3 on MOFs for constructing Z-scheme heterojunction to degrade the refractory organic dyes.

Three-Dimensional Hierarchical Seaweed-Derived Carbonaceous Network with Designed g-C3N4 Nanosheets: Preparation and Mechanism Insight for 4-Nitrophenol Photoreduction.

The development of g-C3N4-based photocatalysts with abundant active sites is of great significance for photocatalytic reactions. Herein, a smart and robust strategy was presented to fabricate three-dimensional (3D) g-C3N4 nanosheet-coated alginate-based hierarchical porous carbon (g-C3N4@HPC), including coating melamine on calcium alginate (CA) hydrogel beads, freeze-drying hydrogel beads as well as pyrolysis at high temperatures. The resulting photocatalyst possessed a significantly high surface area and a large amount of interconnected macropores compared with porous carbon without the melamine coating. The unique structural features could effectively inhibit the curling and agglomeration of g-C3N4 nanosheets, provide abundant photocatalytic active sites, and promote mass diffusion. Therefore, the g-C3N4@HPC composite exhibited remarkable photocatalytic activity and outstanding stability toward the photoreduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 under natural sunlight and simulated visible-light irradiation (λ > 420 nm) using a 300 W xenon lamp. Moreover, the mechanism toward the photocatalytic reaction was extensively studied by quenching experiments and electron spin resonance (ESR) experiments. The results showed that active hydrogen species were able to be achieved by following a dual-channel pathway in the NaBH4 system, which included photocatalytic reduction of H+ ions and photocatalytic oxidation of BH4- ions. This work not only opens up a new way to design efficient photocatalysts for various reactions but also provides a reference for an in-depth study of the photoreduction mechanism.