Visible Light Irradiation In Presence Research Articles

Insight into the melamine-derived freeze-dried nanostructured g-C3N4 for expeditious photocatalytic degradation of dye pollutants

Efficient g-C3N4 photocatalysts have been successfully fabricated with different synthesis approaches. The XRD patterns confirm formation of g-C3N4 nanostructures. The freeze-dried samples exhibit the porous sheet like morphology, and FTIR analysis confirms the CN heterocycles. The zeta potential studies reveal that g-C3N4 nanostructures have more negative surface charge density. The catalysts degrade the organic pollutant Methylene Blue (MB) and Rhodamine B (RhB) in the presence of visible light irradiation. Freeze-dried g-C3N4 catalyst demonstrations expeditious photocatalytic degradation the MB (98.8 %) and RhB (98.6 %) dye in 40 min. The maximum photocatalytic degradation performance because of its low e-h recombination rate, wide range of absorption light, more photo-generated electrons and larger specific surface area. Trapping test confirms that photogenerated electrons will be the main reason for the efficient degradation of organic dyes (MB). The repeatability experiment results evidently confirm the prepared catalyst have high photo-stability. The obtained degradation efficiency results were competing with the many previously reported photocatalyst. These attempts will be useful to realize the photocatalytic mechanism of g-C3N4 with respective different synthesis routes.

Facile fabrication of Ag nanoparticles: An advanced material for antioxidant, infectious therapy and photocatalytic applications

• Bio-compatible AgNPs were synthesized via Carissa opaca leaves extract. • The eco-friendly green prepared AgNPs exhibited antibacterial activity against multidrug resistant bacteria. • AgNPs showed excellent antioxidant and photocatalytic activities. • The said nanoparticles exhibited very weak hemolytic activity. In this modern era, the bacterial resistance towards the newly synthesized drugs is also the keen interest area for the researcher to meet the demands of social people. The plant based green synthesis of nanomaterials attracted tremendous research attention over chemical methods due to their simplicity and ecofriendly and cost effectiveness. The present study was carried out to synthesize silver nanoparticles (AgNPs) using Carissa opaca leaves extract as a capping and reducing agent. The leaf extract has been significantly improved the production of non-toxic AgNPs, due to the presence of various phytochemical and biomedical compounds that are beneficial for catalytic and biological applications. The structure, morphology, elemental composition and size of as synthesized AgNPs were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray (EDS) and dynamic light scattering (DLS). Additionally, the Fourier transmission infrared spectroscopy (FT-IR) was used to identify the functional groups, which might be responsible for the synthesis of AgNPs. The sharp band at 448 nm were observed for UV analysis which confirms the formation of AgNPs. Due to high surface area, controllable size and exceptional morphology, the AgNPs has demonstrated its efficient ability to degrade 97% of MB in 50 min under the presence of visible light irradiation. Additionally, AgNPs showed potential antibacterial activity against multidrug resistant Escherichia coli ( E. coli ) and Bacillus subtilis ( B. subtilis ) with inhibition zone of 20(±0.8 mm) and 24(±0.5 mm), respectively. Moreover, the biogenic AgNPs possessed better antioxidant activity to effectively scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH). Interestingly, the cytotoxicity study revealed that AgNPs is nontoxic to ordinary healthy Red blood cells (RBCs). The results suggest that synthesis of AgNPs was a cost effective, green approach and might be a potential candidate for the biomedical and photocatalytic applications.

Green synthesis, characterization, photocatalytic activity, and biological applications of gelatin-sodium alginate zinc oxide nanocomposite

The present study stated a green approach for synthesizing zinc oxide nanoparticles using Oldenlandia umbellata (Rubiaceae) plant extract, which was used as the biological reducing agent for synthesizing zinc oxide nanoparticles from zinc nitrate hexahydrate. The synthesized ZnO nanoparticles were loaded with Gelatin-Sodium alginate biopolymers to convert them into Gelatin-Sodium alginate-Zinc oxide (GSZnO) nanocomposite hydrogels. The UV–Visible spectroscopy showed maximum absorbance at 376 nm for ZnO Nanoparticles and 360 nm for GSZnO nanocomposite. Different functional groups in ZnO Nps and GSZnO nanocomposites are identified using FT-IR spectroscopy. The SEM analysis of ZnO Nps and GSZnO nanocomposites demonstrates the size in the range of 67–80 nm. DLS Particle size analysis shows 71 nm for ZnO.A NPs and 74 nm for GSZnO nanocomposites. XRD analysis proved the crystalline nature and sharp highest peak at 101) plane confirm the hexagonal shape. While the EDAX analysis confirmed the formation of zinc oxide in the nanoparticles. Antioxidant studies were carried out for ZnO.A Nps showed better antioxidant properties compared to plant extract. The antimicrobial activity of plant extract and ZnO.A Nanoparticles were done against Staphylococcus aureus, Proteus vulgaris, Aspergillus flavus, and Candida albicans. ZnO.A nanoparticles showed good photocatalytic activity of methylene red dye in the presence of visible light irradiation. GSZnO nanocomposite was studied for In-vitro cytotoxicity on Vero cells, The IC50 value for the GSZnO nanocomposite was 101.5 µg/ml.

Nitrogen Doped Titanium Dioxide (N-TiO2): Synopsis of Synthesis Methodologies, Doping Mechanisms, Property Evaluation and Visible Light Photocatalytic Applications

Titanium dioxide (TiO2) is one of the stable and potential metal oxide semiconductor nanomaterials with flexible properties which allows them to be used in a variety of applications (i.e., environmental remediation, energy storage and production, and also as a pigment in personal care products, etc.). However, its low surface area, poor adsorption capacity and high bandgap energy (~3.2 eV) prevents its full potency. Especially, TiO2 with high bandgap (~3.2 eV) reduces its visible light absorption capacity and catalytic efficiency. Various modification processes (i.e., metal and non-metal doping, composite materials (mixed metal oxide, high surface area adsorbents), and dye sensitization etc.) have been accomplished for stimulating the characteristics of TiO2 and the associated catalytic efficiency. Among the modifications, the non-metal doping process in TiO2, specifically nitrogen doping, is one of the efficient dopants for enhancing the photocatalytic efficiency of TiO2 in the presence of visible light irradiation. However, the morphology of TiO2, structural changes in TiO2 during N-doping, properties (e.g., morphology and electronic) of N-doped TiO2 and also reaction operational parameters (e.g., doping concentration) hold a greater impact for enhancing the photocatalytic properties of TiO2 either positively or negatively. Furthermore, the synthesis methodologies have a major influence on the synthesis of stable N-TiO2 with pronounced photocatalytic efficiencies. Nevertheless, the methodologies for highly stable N-TiO2 synthesis, properties evaluation and their correlation with photocatalytic efficiencies are still not appropriately stabilized to accomplish the commercial utilization of N-TiO2. Therefore, this review article focuses on the synopsis of various synthesis methodologies and either their efficiencies or inefficiencies, the mechanism involved in the doping processes, changes in the structural, electronic and morphological properties observed due to the N-doping along with the photocatalytic capacity. Furthermore, the opportunities, challenges and future requirements linked to the development of durable N-doped TiO2-based semiconductor nanomaterials for efficient catalytic performance is also represented.

Catalytic degradation of methyl red using PZnW11/m‐Go as a high‐performance photocatalyst

AbstractIn this research, zinc (II)‐substituted Keggin‐type polyoxometalate [(C4H9)4N] PZnW11O39 (PZnW11) was prepared and stabilized on the modified graphene oxide (m‐GO) for removal of methyl red (MR) dye from aqueous solution. The maximum dye degradation and significance of variables on the decolorization system in static conditions were determined using response surface methodology (RSM). The main variables affecting the decolorization performance on dye decolorization, including system temperature (25–40°C), catalyst amount (0.001–0.005 g), and irradiation time (5–25 min), were evaluated. The optimum temperature, catalyst applying amount, and irradiation time were identified as 35°C, 0.003 g, and 20 min, respectively, and the experimental dye removal value was 96.8%. The high regression coefficient between the response and the variables (R2 = 0.9335) showed a good investigation of the experimental results by regression‐based polynomial model. In comparison with the previously reported photocatalytic decolorization systems, the dye removal system suggested in this work is quick, easy and involves a small amount of catalyst. Polyoxometalate‐based photocatalyst (PZnW11/m‐GO) shows potent visible‐light photocatalytic activity for the decolorization of methyl red dye, due to the generates the strong oxidants hydroxyl radical (OH) and superoxide anion radical (O2−) via photoelectrochemical decomposition of H2O and O2 in the presence of visible light irradiation. Efficient decolorization and degradation of organic contaminants by synthesized catalyst PZnW11/m‐GO suggest its potential for real industrial applications in removal of synthetic dye wastewater.

Hydrothermal Synthesis of Ce-doped ZnO Heterojunction Supported on Carbon Nanofibers with High Visible Light Photocatalytic Activity

Ce/ZnO decorated carbon nanofibers(CNFs) heteroarchitectures(Ce/ZnO/CNFs) have been synthesized using electrospinning technique followed hydrothermal method, which have a high visible light photocatalytic activity. The samples were characterized by means of SEM, FTIR and XRD. The photocatalytic performance of Ce/ZnO/CNFs was tested with the methylene blue in the presence of visible light irradiation. In this work, we have analyzed the effects of Ce doping amount, initial methylene blue(MB) concentration and dosage of Ce/ZnO/CNFs on photocatalytic efficiency of the composite. The results showed that the photocatalyst containing 1.0% Ce in molarity(CZC1) obtained by autoclaving at 150 °C has the best photocatalytic degradation of MB than other as-synthesized samples. Ce/ZnO/CNFs catalysts exhibit a good stability and reusability, which would be an economical and environmentally friendly photocatalyst for various practical applications.

Cu2O/rGO as an efficient photocatalyst for transferring of nitro group to amine group under visible light irradiation

In this investigation, we prepared and developed a photocatalyst for catalyzing the reduction of nitroaromatic compounds to their corresponding aromatic amines with hydrazine monohydrate. The photocatalyst (Cu2O/rGO) was synthesized through the simultaneous reduction of Cu(OAC)2 and graphene oxide which led to the formation of rGO (reduced graphene oxide) sheets grafted by Cu2O. The prepared photocatalyst was studied and identified by FTIR, GC/MS, DRS, XPS, XRD, FESEM, TEM, EDAX, BET and Raman spectroscopy. These studies shows that 2D rGO is well-decorated by Cu2O nanoparticles. Cu2O/rGO was used as photocatalyst for the reduction of nitroaromatic compounds to their corresponding ammine in the presence of visible light irradiation with hydrazine monohydrate. The recyclability of the catalyst was evaluated for six times which showed no significant variation in the reaction conversion.

Microwave-assisted sol–gel synthesis of TiO2-mixed metal oxide nanocatalyst for degradation of organic pollutant

Abstract Titanium dioxide (TiO2) is the most effective photocatalysts for low-cost degradation of organic pollutant; however, the wide band gap and the high recombination rate of the charge carriers are drawbacks that hinders it practical application. In this study, TiO2 and titanium mixed metal oxides ternary (V/Ag/TiO2) nanocatalyst was synthesized through a microwave-assisted sol–gel route using Ti(C4H9O)4, NH4VO3, and AgNO3 as precursors. The XRD analysis of the synthesized TiO2 and V/Ag/TiO2 depicts lattice fringes for rutile and anatase crystalline phases. Raman spectra indicate the formation of a mesoporous multiphase sample mixture of rutile and anatase phases. The spectrum shift to the visible light region was demonstrated by the UV-visible spectroscopy analysis. Diffuse reflectance spectroscopy (DRS) reveals a reduced band gap of 2.9 eV for TiO2 and 2.65 eV for V/Ag/TiO2. Brunauer–Emmett–Teller (BET) indicates a large surface area of 92.8 and 84.8 m2 g−1 for TiO2 and V/Ag/TiO2, respectively. Nitrogen adsorption–desorption isotherm exhibits type IV isotherm, signifying the presence of the mesoporous structure. SEM portrays a cluster of rod-like aggregate particles, while the HRTEM analysis illustrates nanoparticles of rod-like cylindrical shape with a homogeneous size diameter. The synthesized nanocatalyst demonstrated a significant photocatalytic ability in the degradation of methyl orange (MO) and methylene blue (MB). V/Ag/TiO2 shows higher activity in the visible region. Thus, the present report suggests efficient, suitable, and economical microwave-assisted sol–gel techniques to yield V/Ag/TiO2 nanocatalysts with harnessed photocatalytic performance for the degradation of toxic organic pollutants in the presence of visible light irradiation.

Efficient synthesis of a new heterogeneous gold nanocatalyst stabilized by di-alkyne ligand and its applications for photocatalytic dye degradation and transfer hydrogenation reaction

A new form of carbon-based ligand supported robust heterogeneous gold nanocatalyst was synthesized and its potential catalytic applications are demonstrated. The high yield (> 90%) synthesis procedure involves ligand exchange between hydrophilic polyvinylpyrrolidone polymer stabilized gold nanoparticles (Au:PVP) with a di-alkyne ligand (1,4-Diethynylbenzene). The ultrasmall stabilized gold nanoparticles (1.8 ± 0.3 nm) are bonded to di-alkyne ligand through acetylenic carbon atom (≡C-Au) with an electronically conjugated 3D network. The synthesized material (Au-P1) was meticulously characterized using several spectroscopic and microscopic techniques, e.g., Fourier transform infrared spectroscopy (FTIR), optical absorption spectroscopy (UV-Vis), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM) and thermogravimetric analysis (TGA). The Au nanocatalyst showed good photocatalytic activity for degradation of several organic dye molecules in aqueous phase under visible light irradiation in presence of oxidizing agent (H2O2). The proposed mechanism involves dye absorption on ligand surface through π-π interaction followed by transfer of electron from excited dye molecules to gold core through electronically conjugated ligand for generation of reactive oxygen species (·OH). The catalyst has also been demonstrated for transfer hydrogenation of organic carbonyl and nitro functional groups (>C=O, -NO2) with potassium formate (HCOOK) as hydrogen source in water. The catalyst could be recovered by simple filtration, and it was reused up to five cycles for both of these catalytic transformations with complete retention of its catalytic activity.

Enhanced photocatalytic degradation efficiency of graphitic carbon nitride-loaded CeO2 nanoparticles

In the present study, we have evaluated the photocatalytic potentials of ceria (CeO2) loaded graphitic carbon nitride (GCN; g-C3N4) composite towards the degradation of two different organic dyes. The CeO2/GCN composite following its formation by the co-precipitation route, the physicochemical properties like crystallinity, functionality, optical, and morphology are being studied using various instrumental techniques such as powdered X-ray diffraction (XRD), Fourier transforms–infrared spectroscopy (FTIR), UV–Vis diffuse reflection spectroscopy (UV–Vis), and field emission scanning electron microscopy (FESEM). From the analysis, the XRD studies indicated that the composite has the cubic structure of ceria and hexagonal phase for the GCN. The FTIR analysis supported for the successful formation of CeO2/GCN composite and UV–Vis provided the optical properties indicated to have the bandgap energy values of 3.12 and 2.86 eV for pure CeO2 and CeO2/GCNcomposite (respectively). Also, the FESEM confirmed for the surface morphology of CeO2/GCN composite, and finally, the test of photocatalytic activity studied in the presence of visible light irradiation towards the degradation of Methyl blue (MB) and Rhodamine-B (Rh-B) dyes indicated for the superior activity of CeO2/GCN composite as compared to the single-phase GCN and pure CeO2. Based on the cumulative analysis of results, it can be informed that the CeO2/GCN composite can be useful for the sustainable means of degradation of organic dyes (MB and Rh-B) by taking advantage of the synergistic impact of the two components of CeO2 and GCN.

Ultrasonochemically Modified Ag@TiO2 Nanocomposites as Potent Antibacterial Agent in the Paint Formulation for Surface Disinfection

AbstractAdvanced visible active antibacterial paint was developed by ultrasonochemically treated Ag@TiO2 NCs with varying content of Ag (1 wt. % to 5 wt. %) as a photoactive agent for antibacterial paint formulation for surface disinfection. Initially, the existence of the Ag@TiO2 NCs in the paint formulation and their impact with varying content of Ag in wt. % was studied through various spectroscopic studies. XRD analysis confirms the good crystalline nature of the Ag@TiO2 NCs after the paint formulation. UV visible spectroscopic study reveals the visible active properties of the antibacterial paint. Contact angle measurement study shows hydrophobic nature of the paint. Thereafter, Ag@TiO2 NCs with varying the content of Ag were used as a photoactive additive for the formulation of antibacterial powder paint through an industrial process. Finally, the 3 wt. % of Ag in the Ag@TiO2 NCs as an additive in the paint exhibits higher antibacterial activity against E. coli as compared with S. aureus bacteria's in the presence of visible light irradiation. It also confirmed after 72 hrs. that there was no leaching of the antibacterial paint on the coated substrates. Therefore, such nanocomposite based visible active antibacterial paint is efficient to use in healthcare for reducing hospital‐acquired infections.

Highly efficient activation of peroxymonosulfate by Co3O4/Bi2WO6 p-n heterojunction composites for the degradation of ciprofloxacin under visible light irradiation

Photocatalytic technology assisted via peroxymonosulfate (PMS) has good potential in water treatment. In this study, the Co3O4/Bi2WO6 composite was constructed via an in-situ calcination process and used to activate PMS for the degradation of ciprofloxacin (CIP) under visible light irradiation. The obtained 5 wt% Co3O4/Bi2WO6(CBWO-2) can highly effectively remove 86.2% CIP within 5 min visible light irradiation in presence of PMS. The excellent degradation performance of Co3O4/Bi2WO6/PMS system can be attributed to the synergistic effect between p-n heterojunction and PMS activation. The conduction band and valence band deviation between Co3O4 and Bi2WO6 were calculated by XPS techniques. Besides, DFT calculations were performed to further confirm the internal structure between Co3O4 and Bi2WO6. This work not only provides an approach to fabricate heterostructures but also indicated that Co3O4/Bi2WO6/PMS/Vis system is a potential environment remediation alternative for the efficient removal of recalcitrant organic compounds from wastewaters.

Fabrication of Zn3(PO4)2/carbon nanotubes nanocomposite thin film via sol-gel drop coating method with enhanced photocatalytic activity

Thin films of Zn3(PO4)2 and Zn3(PO4)2/carbon nanotubes (Zn3(PO4)2/CNT) were fabricated on glass substrate by the simple sol-gel drop coating method. The crystal structure, particle size, morphology and optical properties were characterized by X-ray Diffraction, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy (FT-IR) and Ultraviolet-visible Spectroscopy. The X-ray diffraction results revealed the formation of zinc phosphate crystal without any impurities as well as the average particle size of 24 nm and 19 nm for Zn3(PO4)2 and Zn3(PO4)2/CNT, respectively. FT-IR spectral data confirmed the grafting of the polar carboxylic and hydroxyl functional groups on the surface of nanotubes due to functionalization and also the presence of PO43- group. The formation of heterojunction interface between CNT and Zn3(PO4)2 reduce the fast recombination of charge carriers, which leads to the high photoenergy conversion efficiency. The as-synthesized Zn3(PO4)2/CNT composite thin film showed highest photocatalytic efficiency for the degradation of cationic organic dye methylene blue under ultraviolet (UV) (85%) and visible (53%) light irradiation. Incorporation of CNT with the Zn3(PO4)2 enhanced the photocatalytic efficiency two fold in case of UV and four fold higher in presence of visible light irradiation as high as bare Zn3(PO4)2. We offer that this work will smooth the progress of preparation of innovative phosphate based photocatalysts for degradation of organic pollutants from environment under UV light illumination. Furthermore, a plausible photocatalytic degradation mechanism of an organic pollutant by the synthesized Zn3(PO4)2/CNT composite is proposed.

Internal electric field induced S–scheme heterojunction MoS2/CoAl LDH for enhanced photocatalytic hydrogen evolution

The requisite interfacial contact of heterojunction photocatalysts has a significant contribution in separation of interfacial charge carriers for photocatalytic hydrogen (H2) evolution in a more efficient manner. Herein, an internal electric field (IEF)-induced S–scheme system comprised of two-dimensional (2D) CoAl layered double hydroxide (LDH) and 2D molybdenum disulfide (MoS2) was constructed via a simple hydrothermal process. In the presence of visible-light irradiation, the 2D/2D MoS2/CoAl LDH hybrid demonstrates eightfold greater photocatalytic H2 generation rate as compared with that of CoAl LDH. The mechanism was investigated in the light of the results of the X-ray photoelectron spectroscopy (XPS) and work-function calculated by density functional theory (DFT) simulation, and the improved activity was ascribed to that the rapid detachment of the electron-hole (e−-h+) combinations and high redox ability, both are simultaneously realized in MoS2/CoAl LDH hybrid with a 2D/2D S–scheme charge transfer mechanism induced by the IEF across interface of the MoS2 and CoAl LDH. Furthermore, favorable 2D/2D structure and better H* adsorption behavior of MoS2/CoAl LDH also promoted the improvement of water reduction performance. This work is a valuable guideline in developing of IEF-induced S–scheme photocatalysts with 2D/2D architecture for improved photocatalytic performance.

In situ decoration of Ag nanoparticles on hierarchical TiO2 nanowire nanofibers with enhanced catalytic activity used for the removal of 4-nitrophenol

Hierarchical materials are of great interest toward the development of catalysts because of their unique structures and large specific surface area. In this study, Ag-decorated TiO2 (TiO2@Ag) nanowire nanofibers (NW NFs) were synthesized via the in situ decoration of Ag nanoparticles (NPs) on hierarchical TiO2 NW NFs and their microstructure and catalytic activity for the removal of 4-nitrophenol were evaluated. TiO2 NW NFs were first synthesized via the hydrothermal reaction of the electrospun TiO2 NFs in a concentrated NaOH solution and then hydrothermally treated in a AgNO3 solution to form the TiO2@Ag NW NFs. SEM observations showed that the TiO2@Ag NW NFs were assembled from numerous TiO2 NWs subunits and exhibited a hierarchical and fibrous morphology with diameters in the range of 1–2 μm and lengths of tens of micrometers. TEM observations showed that many Ag NPs with diameters in the range of 4–10 nm were well grown on each TiO2 NW with diameters of 20–40 nm. It was found that the TiO2@Ag NW NFs showed catalytic activity for the removal of 4-nitrophenol (4-NP), a representative contaminant. The catalytic removal efficiency of 4-NP by the TiO2@Ag NW NFs in the presence of visible light irradiation (0.639 min−1) was 3.2-fold higher than that in the absence of light irradiation (0.199 min−1), indicating that the TiO2@Ag NW NFs exhibit visible light-enhanced catalytic activity.

Investigation on photo-induced mechanistic activity of GO/TiO2 hybrid nanocomposite against wound pathogens

Pathogenic microorganism delays wound-healing process by causing infection. In recent years, researchers have developed various kinds of photo-active nanomaterials with enhanced antibacterial properties. This work focus on the preparation of graphene oxide and TiO2 nanocomposites (GO/TiO2) as a visible light-induced high efficiency antibacterial material. The hydrothermal method was used for the synthesis of GO/TiO2 nanocomposites at 180 oC for 3 h with different loading percentages of GO (10, 20, 30, 40 and 50 wt. %). The systematic characterization tools including X-ray diffraction analysis, FT-IR, UV-vis, Raman and TEM which were used to understand the physicochemical properties of the prepared GO/TiO2 nanocomposites. Furthermore, GO/TiO2 nanocomposites were used as photocatalytic active materials against wound infection-causing bacteria in the presence of visible light irradiation. The possible antibacterial mechanism under presence and absence of light were depicted. The antibacterial mechanism of the GO/TiO2 nanocomposite was investigated on wound infection-causing bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis. The high hemocompatibility and the cellular biocompatibility of the nanocomposite aids in using it for wound-healing application. Overall, the results suggest that the GO/TiO2 nanocomposite could be developed as a photo-active nanomaterial against pathogenic microorganisms that are present in wound.

Structural Insights on 2D Gadolinium Tungstate Nanoflake: A Promising Electrocatalyst for Sensor and Photocatalyst for the Degradation of Postharvest Fungicide (Carbendazim).

Gadolinium tungstate (Gd2(WO4)3) has acquired much attention owing to its exclusive transport properties and excellent thermal and chemical stability. In this work, we demonstrate that two-dimensional (2D) gadolinium tungstate nanoflakes (GW Nfs) are synthesized by a coprecipitation method and represent novel architectures for efficient catalysis, which could be used in electrochemical sensing and photocatalytic degradation of the postharvest fungicide carbendazim (CBZ). The physicochemical properties of GW Nfs were studied by using XRD, Raman, TEM, EDX, and XPS, which show the formation of GW as a nanoflake-like structure with a well crystallized nature. The as-prepared GW Nfs revealed an admirable electrochemical response for CBZ detection with an LOD of 0.005 μM, a wide-ranging linear response of 0.02 to 40 μM, and a notable sensitivity of 0.39 μA μM-1 cm-2. Furthermore, the GW-Nf-modified electrode has a good recovery for CBZ in the study of real samples such as rice and soil washed water samples. Moreover, GW Nfs have a promising photocatalytic activity for CBZ degradation. The GW Nfs could degrade CBZ at greater than 98% efficiency and mineralize above 74% of the CBZ molecules in the presence of visible light irradiation with superior stability even after many cycles. Subsequently, the electrochemical and photocatalytic mechanisms were provided in detail.

Synthesis of polymer-supported Brønsted acid-functionalized Zn–porphyrin complex, knotted with benzimidazolium moiety for photodegradation of azo dyes under visible-light irradiation

A polymer-supported Bronsted acid-functionalized Zn–porphyrin complex, knotted with benzimidazolium moiety (PSBAZnPP), has been synthesized and characterized by Fourier transform nuclear magnetic resonance (FT-NMR) and Fourier transform infrared spectroscopy (FTIR). The thermal stability was determined by thermogravimetric analysis (TGA), and surface morphology and elemental composition were investigated by scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDAX). The heterogeneous PSBAZnPP showed high efficacy as a photocatalyst for degradation of azo dyes, such as methyl red (MR), methyl orange (MO) and Congo red (CR), in the presence of visible-light irradiation at ambient condition using atmospheric air/H2O2. The concentration of the dyes was measured by UV–visible spectroscopy, and the degradation of the dyes was confirmed by GC–MS analysis. Further decolorization and degradation of MO were confirmed by using ultra-high-pressure liquid chromatography (UPLC). The optimum degradation was achieved by adding 10 mg catalyst for all azo dyes for 60 min in the presence of air. The effect of scavengers was studied to indicate the most active species generated during photocatalysis. PSBAZnPP furnished a good response toward the photodegradation of MR, MO and CR under optimized conditions. Finally, the mechanism of photocatalytic degradation process was suggested. Relevant active species produced in the PSBAZnPP/H2O2 or PSBAZnPP/air system under visible light were recognized by using different types of scavengers, viz. EDTA, p-benzoquinone (PBQ), terephthalic acid (TPA), sodium azide and sodium nitrate, for determination of formation of holes, $${\text{O}}_{2}^{ \cdot }$$, $${\text{OH}}^{ \cdot }$$, $${}^{1}{\text{O}}_{2}$$ and an aqueous electron (e−), respectively. The comparative acidity of the synthesized PSBAZnPP catalyst was measured using UV–Vis and then equated to relations of the Hammett value (H0). The efficiency of catalyst correlates with a considerable proton level required for degradation of organic dyes.

Revealing high hydrogen evolution activity in zinc porphyrin sensitized hierarchical porous TiO2 photocatalysts

In this work, a dye/TiO2 system for hydrogen generation via the reduction of water has been investigated. The use of simple and template free synthesis process for hierarchical porous architecture of TiO2 (HPT) with a panchromatic Zinc-porphyrin (LG5) sensitizer has been identified as the potential material in photoinduced hydrogen production. The effect of the dye absorbed by the Pt-HPT has been tested for the hydrogen production under visible light irradiation in presence of triethanolamine (TEOA) or Glycerol (Gly) as sacrificial electron donor (SED). The enhanced activity and effective charge transfer from the dye to the TiO2 molecule is significant in the PHPT-LG5 composite. The PHPT-LG5 catalyst exhibited higher photocatalytic activity of 4196 μmol g−1 h−1 with an impressive turnover numbers (TON) of 8392 and apparent quantum yield (AQY) of 7.43% of light irradiation using 450 W Xe lamp when compared to the corresponding simple semiconductor as well as the N719 dye loaded catalysts. The acrylic group present in the dye molecule helps in binding the semiconductor with the dye molecule and leads to superior photocatalytic activity. The diffuse reflectance spectroscopy (DRS), and computational studies of the dye molecule and the composite suggests the better photocatalytic performance of the composite. The Fourier Transform Infra-Red Spectroscopy (FTIR) studies reveals the strong attachment of the dye molecule with the semiconductor hierarchical porous TiO2 (HPT) results in the enhancement in hydrogen production, the stability tests of the photocatalyst shows higher reproducibility at neutral pH in TEOA. A systematic study of LG5 with sacrificial electron donors and pH were performed and are correlated with the photocatalytic activity of N719 dye. The presence of the cyanoacrylic group as an anchoring group in the LG5 leads to red shift in S and Q bands suggesting the efficient intramolecular charge transfer behavior (CT) and possess strategies for broadening the light harvesting properties. The present work opens up a new window toward solar energy conversion with extended light harvesting capacity and enhanced photocatalytic activity.

Visible Light-driven Photocatalytic Performance of Zno Coupled with Up-conversion Phosphors for the Removal of Methylene Blue

In this work it was investigated the photocatalytic activity of ZnO coupled with inorganic “up-conversion” phosphors for the treatment of aqueous solutions polluted with methylene blue (MB), in the presence of visible light irradiation. Specifically, the successfully prepared “up-conversion” phosphors nanoparticles emit, when excited with visible light, UV light with main emission at 365 nm. The photocatalytic tests were carried out in a cylindrical pyrex photoreactor equipped with a magnetic stirrer to ensure the continuous mixing of the physical mixtures of “up-conversion” phosphors and commercial ZnO nanoparticles in the solution and irradiated by visible light instead of UV light normally required to excite ZNO. Experimental results were analysed by evaluating the MB decolourization through spectrophotometric method and the total organic carbon (TOC) through high temperature combustion method. In particular, it was found that the photocatalytic performances obtained using ZnO nanoparticles coupled with “up-conversion” phosphors are strongly increased compared to the use of ZnO alone. These results confirmed the enhancement of photocatalytic performances induced by UV photons emitted by “up-conversion” phosphors nanoparticles, able to activate ZnO, demonstrating how their use in photocatalytic systems can be an alternative to the traditional UV lamps, thus preserving human health, environmental and, at the same time, allows to save the energy in process management.