Direct Sunlight Irradiation Research Articles

Study of thermochromic and photocatalytic properties of MoO3 thin films

Molybdenum trioxide (MoO 3 ) thin films with thicknesses 300, 400 and 500 nm were deposited on an FTO substrate by thermal evaporation method. The prepared thin films showed both thermochromic and photocatalytic dye degradation properties. The thermochromic property of the prepared thin films was induced by exposing the thin films to argon gas at a temperature varying from 100 °C to 300 °C (in steps of 50 °C). The photocatalytic dye degradation ability of the films were examined by the photodegradation of methylene blue (MB) dye solution under visible light irradiation. MoO 3 thin film with 300 nm thickness is seen to have good thermochromic and photocatalytic dye degradation ability and both of these properties are necessary for smart window applications. • Synthesis of MoO 3 thin films by thermal evaporation method. • Thermochromic property of MoO 3 thin films. • Photocatalytic activity under direct sunlight irradiation. • Promising thin film for eco-friendly smart window application.

A rutile phase-TiO2 film via a facile hydrothermal method for photocatalytic methylene blue dye decolourization

In this work, we have fabricated rutile- phase TiO2 film on a fluorine doped tin oxide (FTO) substrate by a facile hydrothermal method and studied for methylene blue (MB) dye decolourization under direct noon sunlight irradiation. The prepared film was characterized by UV–visible spectroscopy, X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), Raman spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). XRD analysis confirms that the hydrothermal treatment facilitated the crystallization of the rutile TiO2 phase on FTO plate. The functional group, surface morphology and structural property were analyzed from FTIR and FESEM respectively. The optical band-gap was evaluated to be 3.2 eV from the UV–visible spectroscopy. The photocatalytic activity of rutile-TiO2 film was evaluated which showed 78 % Methylene blue dye decolourization in 240 min.

Probing the photocatalytic competency of hydroxyapatite synthesized by solid state and wet chemical precipitation method

In this work, we have demonstrated a comparative investigation on the photocatalytic competency of hydroxyapatite (HAp) prepared by solid state (S-HAp) and wet chemical (W-HAp) precipitation method. Both synthesis protocols utilized eggshell and di-ammonium hydrogen phosphate as the Ca and P precursors respectively while the calcination temperature was fixed at 900 °C. In both cases, X-ray diffraction analysis exposed that the synthetic HAp is biphasic in nature where β-tricalcium phosphate (β-TCP) appeared as the 2nd phase but obviously, the % volume ratio of the later phase was different. Methylene blue (MB), a most accustomed model dye was chosen as the targeted pollutant for photodegradation study and the reaction was carried out using both indoor (simulated sunlight) and outdoor (direct sunlight) irradiation. The photodegradation efficacy of both types of HAp was appraised by monitoring the dye degradation rates. It was clearly noticed that HAp prepared by solid state method triggered the photo-process more actively. S-HAp showed an efficacy of 99.82% under sunlight irradiation and 98.53% under simulated sunlight irradiation (0.2 g S-HAp; 40 ml 10 × 10−6 M MB; pH-9; 120 min irradiation time). On the contrary, W-HAp exhibited only 23.15% efficacy under solar irradiation and 18.76% under simulated sunlight irradiation (0.2 g W-HAp; 40 ml 10 × 10−6 M MB; pH-7; 120 min irradiation time). The reason for greater activity of S-HAp could be the consolidated effect of its inferior crystallinity as well as the capability of generating more active species with the presence of higher percentage of β-TCP.

Charge-transfer regulated visible light driven photocatalytic H2 production and CO2 reduction in tetrathiafulvalene based coordination polymer gel

The much-needed renewable alternatives to fossil fuel can be achieved efficiently and sustainably by converting solar energy to fuels via hydrogen generation from water or CO2 reduction. Herein, a soft processable metal-organic hybrid material is developed and studied for photocatalytic activity towards H2 production and CO2 reduction to CO and CH4 under visible light as well as direct sunlight irradiation. A tetrapodal low molecular weight gelator (LMWG) is synthesized by integrating tetrathiafulvalene (TTF) and terpyridine (TPY) derivatives through amide linkages and results in TPY-TTF LMWG. The TPY-TTF LMWG acts as a linker, and self-assembly of this gelator molecules with ZnII ions results in a coordination polymer gel (CPG); Zn-TPY-TTF. The Zn-TPY-TTF CPG shows high photocatalytic activity towards H2 production (530 μmol g−1h−1) and CO2 reduction to CO (438 μmol g−1h−1, selectivity > 99%) regulated by charge-transfer interactions. Furthermore, in situ stabilization of Pt nanoparticles on CPG (Pt@Zn-TPY-TTF) enhances H2 evolution (14727 μmol g−1h−1). Importantly, Pt@Zn-TPY-TTF CPG produces CH4 (292 μmol g−1h−1, selectivity > 97%) as CO2 reduction product instead of CO. The real-time CO2 reduction reaction is monitored by in situ DRIFT study, and the plausible mechanism is derived computationally.

Facile synthesis of cationic surfactant-treated hierarchical nanorods SnO2@CdO nanocomposite photocatalyst for degradation of methylene blue under sunlight

CTAB-treated hierarchical nanorods cadmium oxide nanorods loaded tin oxide (SnO2@CdO/CTAB) nanocomposite has been prepared by simple chemical co-precipitation technique. The X-ray diffraction pattern analysis revealed the as-prepared CTAB-treated nanocomposites possess tetragonal rutile structure having appreciable crystallinity with crystallite sizes in the range of 100–115 nm. The diffuse reflectance absorption spectrophotometer investigation confirms that the efficient absorption band of SnO2@CdO/CTAB nanocomposites have red shift over the SnO2. Fourier transform infrared spectroscopy (FTIR) investigation confirms the prepared SnO2@CdO/CTAB nanocomposites encompass the characteristic bands of both SnO2 and CdO. The morphology of the prepared nanocomposites were performed by FESEM and shows that hierarchal nanorods structure. The EDX analyses revealed all the samples are composed of Sn and O elements. The photocatalytic performance of the prepared SnO2@CdO/CTAB hierarchical nanorods nanocomposites was evaluated via methylene blue (MB) dye removal under direct natural sunlight irradiation.

Nb2O5/g‐C3N4 Heterojunction Facilitates 2,5‐Diformylfuran Production via Photocatalytic Oxidation of 5‐Hydroxymethylfurfural under Direct Sunlight Irradiation

AbstractHerein, we report the enriched synthesis of 2,5‐diformylfuran (DFF) from 5‐hydroxymethylfurfural (HMF) over a Nb2O5/g‐C3N4 heterojunction under direct sunlight irradiation. The analytical characterization established the improved quality of the heterojunction compared to the original characteristics of the single photocatalysts, especially the surface properties and alignment of band edge positions, towards the control of recombination of the charge carriers for its application in the photocatalytic oxidation of HMF. Acetonitrile possessing a moderate polarity provided significant assistance in the higher HMF conversion (72 %), resulting in a 61 % wt. DFF yield and 84 % selectivity under modest reaction conditions. The result is comparatively 1.5 to 3.3 times higher than the single photocatalysts (g‐C3N4 and Nb2O5) under similar conditions, indicating the potential of the heterostructure (type‐II heterojunction) in DFF synthesis through the synergistic action of Nb2O5 and g‐C3N4 by controlling the e−–h+ pair recombination. Moreover, the heterojunction enabled selective conversion without the supply of O2 gas or oxidizing agent. The photogenerated holes (h+) played a key role in the augmented HMF conversion (based on radical trap studies), which obeyed first‐order kinetics.

Photocatalytic activity of dye‐sensitized and non‐sensitized GO‐TiO2 nanocomposites under simulated and direct sunlight

AbstractGraphene oxide (GO), amine‐modified graphene oxide (mGO), and N‐TiO2 composites were synthesized by low‐temperature hydrothermal method and characterized by using X‐ray diffraction, X‐ray photoelectron spectroscopy, FTIR, and BET analysis techniques. The films of synthesized TiO2, mGO:TiO2, N‐TiO2, GO:TiO2, GO:N‐TiO2, and commercially available P25 were prepared by doctor blade method. These films and their perylene‐3,4,9,10‐tetracarboxy tetrabutylester (PTE)‐sensitized forms were employed as photocatalysts for the photodegradation of rhodamine‐B (RhB) under Xe lamp and direct sunlight irradiations. Independent from the irradiation source, the photocatalytic order of the non‐sensitized films were GO:N‐TiO2 > GO:TiO2 > N‐TiO2 > mGO:TiO2 > TiO2 > P25, but seven and 15 folds of increments were detected under direct sunlight irradiation. PTE‐sensitized catalyst films exhibited more than two folds of increase in the photocatalytic rate constants compared to their non‐sensitized counterparts under Xe lamp irradiation. Under direct sunlight irradiation no matter which photocatalyst was used, the photocatalytic activity of these films was enhanced seven folds. Reusability tests revealed no significant changes in the photocatalytic rate constants obtained with both the non‐sensitized and sensitized films.

Preparation of Passive Daytime Cooling Fabric with the Synergistic Effect of Radiative Cooling and Evaporative Cooling

AbstractPassive daytime radiative cooling (PDRC) has attracted intensive attention due to its great potential in reduced energy consumption. However, the practical application for PDRC is greatly affected by geographical location and the intrinsic cooling power. Herein, a composite flexible fabric with the synergistic effect of evaporative cooling and radiative cooling is reported. A porous polymer coating with both a high solar reflectivity (90%) and a high infrared thermal emissivity (83%) is fabricated on the top side of the fabric, which can achieve effective PDRC performance. Meanwhile, hygroscopic salts are loaded on the bottom side of the fabric, which can capture water vapor at night and realize evaporative cooling during the daytime. The temperature reduction of 10.8 °C can be achieved under the direct sunlight irradiation (465 W m−2) for the prepared fabric in the outdoor experiment. The combination of radiative cooling and evaporative cooling breaks through the traditional single passive cooling mode and has great potential in further improving the performance of passive cooling.

Facile preparation of bismuth vanadate-sheet/carbon nitride rod-like interface photocatalyst for efficient degradation of model organic pollutant under direct sunlight irradiation

The photocatalytic performance of a semiconducting catalytic system is strongly influenced by charge-carrier separation rate, charge transport properties, surface area, utilization of light energy, and interface bonding. Herein, a series of bismuth vanadate (BiVO4) samples were prepared via hydrothermal method by changing the volume ratios of ethelene glycol and ethanol as a solvent mixture for bismuth precursors. Further, the optimized BiVO4 sheets with hierarchical morphology were used to construct an interface with rod-like g-C3N4 materials, which was confirmed by HRSEM and HRTEM. Due to the formation of an effective interface bonding between BiVO4/g-C3N4, the photoinduced charge carrier's recombination rate was suppressed as confirmed by the PL analysis. The prepared BiVO4/g-C3N4 sample were used to assess the photodegradation efficiency of Rhodamine B (RhB) under direct sunlight irradiation and the photocatalysts degraded ~92.8% of RhB within 2 h. The TOC measurements revealed a 66.4% mineralization efficiency for RhB. In addition, the radical trapping experiments demonstrated that superoxide and hydroxyl radicals are the main reactive species for the degradation. Based on the experimental evidences, a plausible charge transfer mechanism has been proposed. The enhanced photocatalytic activity has been mainly attributed to the inhibition of the recombination rate, enhanced charge carrier transfer efficiency, and high rate of production of reactive species.

Facile Fabrication of Novel SrMoO4/g‐C3N4 Hybrid Composite for High‐Performance Photocatalytic Degradation of Dye Pollutant under Sunlight

AbstractThe exploitation of the efficient hybrid composite materials for environmental remediation is highly demanding area. In the present work, pristine SrMoO4 (SMO), g‐C3N4 (G‐CN) and SrMoO4/g‐C3N4 (SMO/G‐CN) hybrid composite materials have been synthesized for the first time by facile mixing and heating methodology. The fabricated materials are subsequently characterized by various spectroscopic techniques. Phase analysis was carried out by PXRD study as well as morphology and elemental analysis were investigated by FE‐SEM, EDS and XPS studies. The thermal stability of synthesized materials was determined by TGA as well as optical properties were confirmed by UV‐Vis DRS and PL studies, electrochemical analysis by EIS studies. The results reveals the optimized SMO/G‐CN‐10 composite photocatalyst exhibits superior performance for the photocatalytic degradation of Rhodamine B (Rh B) dye under direct sunlight irradiation and rate of photocatalytic efficiency of SMO/G‐CN‐10 (0.0976 min−1) is 4 and 40 times higher as compared to those of pure G‐CN (0.0245 min−1) and SMO (0.0024 min−1) respectively. Good interfacial interactions between the G‐CN and SMO in SMO/G‐CN‐10 composite helps in the separation and efficient transfer of photo‐induced excitons by inhibiting the recombination of excitons. The trapping experiment results reveals that O2.− are the major reactive species. It was noted that our composite SMO/G‐CN‐10 is found to be stable even after four successive runs. Furthermore a suitable mechanism has been proposed for its enhanced photocatalytic activity. Altogether, in the present investigation, a new route for the synthesis of efficient visible light active photocatalysts has been reported which is not only beneficial for environmental remediation applications but might also be used for the water splitting and CO2 reduction.

Microplasma-assisted electrochemical synthesis of ZnO nanostructures for photocatalytic and antibacterial applications

Zinc oxide nanostructures (ZnO NSs) have been extensively studied because of their many applications in different fields. In this study, an attempt has effectively been made for the synthesis of ZnO nanostructures by using fast and environment-friendly microplasma electrochemical technique. The prepared nanostructures were examined in terms of their morphological, optical, structural, electrical, and compositional properties by using different characterization techniques. Results demonstrated that the highly crystalline ZnO nanostructures were produced with a single hexagonal (wurtzite structure) phase. Results also indicated the crystallite size increases with increasing precursor concentration. The optical band gap of ZnO is found to decrease (from 3.48eV to 3.40 eV) with increasing crystallite size. I-V characteristics of ZnO are measured by two probe technique which shows semiconducting behavior of prepared ZnO. The antibacterial and photocatalytic properties of the synthesized nanostructures were also investigated. It was observed that the degradation efficiency of zinc oxide photocatalyst increases with the irradiation time. About 85% of Rhd B dye was degraded by ZnO after 120 min at a rate of 0.01339 min−1 under direct sunlight irradiation. The antibacterial activity of ZnO was carried out against different gram-positive and gram-negative bacterial strains, by using the diffusion well method. Higher antibacterial activities were observed against gram-negative bacteria as well as for a higher concentration of ZnO. This study will be helpful to synthesize low-cost and effective materials to remove microorganisms and toxic industrial organic dyes which is a serious threat to terrestrial and aquatic life.

Preparation and characterization of the Cu, Fe co-doped Bi2Ti2O7/EG-g-C3N4 material for organic model pollutants removal under direct sun light irradiation

The following hindrances should be overcome to enhance the efficacy of photo-catalysts such as a poor-visible light response, high charge-carrier recombination rate, less surface area, and inappropriate band-edge alignment for photo-induced redox reaction. This study reported, visible light responsive Cu, Fe-co-doped Bi2Ti2O7/EG-g-C3N4 catalyst for photo-removal of organic pollutants. Series of characterization tools are used to testify and demonstrate the properties of formed material. The photo-removal efficiency of Cu, Fe-co-doped Bi2Ti2O7/EG-g-C3N4 hybrids are estimated to be 69.5 and 83.69% for ciprofloxacin and Rhodamine B organic molecules. Free radical trapping experiments were carried to predict active radical's participating in the reaction. The possible reaction mechanism was explained based on band edge potentials and trapping experiment results. This reporting Cu, Fe-co-doped Bi2Ti2O7/EG-g-C3N4 catalyst showed good durability. This work gives a new insight into coupling tactics of Cu, Fe-co-doped Bi2Ti2O7 and g-C3N4 material and which will helpful for designing efficient photocatalytic materials.

Direct sunlight-driven enhanced photocatalytic performance of V2O5 nanorods/ graphene oxide nanocomposites for the degradation of Victoria blue dye

Herein, we report the synthesis and characterizations of Vanadium pentoxide (V2O5) nanorods/graphene oxide (GO) nanocomposite as efficient direct solar light driven photocatalyst for the enhanced degradation of victoria blue (VB) dye. The nanocomposite was synthesized by sonochemical process and characterized using several analytical methods in order to study the structural, morphological, compositional, optical and photocatalytic properties. The X-ray diffraction studies confirmed the orthorhombic structure of V2O5 while the morphological examinations revealed the growth of V2O5 nanorods and 2D GO sheets. Interestingly, the UV studies ratify that the bandgap of the nanocomposite was reduced compared to pure GO and V2O5. Interestingly, the interaction of the V2O5 nanorods with the graphene oxide substrate and its effect on the electronic properties of the combined system, have been examined by means of theoretical calculations, based on the so called Geometry, Frequency, Noncovalent, eXtended Tight Binding (GFN-xTB) method. Studying the photocatalytic behavior of nanocomposite, we observe an almost complete degradation (97.95%) of Victoria Blue (VB) dye under direct sunlight illumination within just 90 min. The outstanding nanocomposite photocatalytic efficiency was due to the excellent transfer of interfacial charge and the suppressed recombination of charge-carrier. The kinetics of the degradation process was also analyzed by calculating the rate constant and half-life time. Finally, a possible mechanism has also been discussed for the degradation process of VB dye using nanocomposite under direct sunlight irradiation.

CdS nanorods supported copper-nickel hydroxide for hydrogen production under direct sunlight irradiation

A series of composite photocatalysts based on CdS nanorods decorated with Cu/Ni hydroxides were prepared via deposition precipitation method at room temperature (total metal loading ≈ 3 wt%). The performance of these photocatalysts was evaluated for H2 production through water dissociation reaction under direct sunlight. The 2.4Cu(OH)20.6Ni(OH)2/CdS photocatalyst with a total 3 wt% nominal metal cocatalyst loading demonstrated an excellent hydrogen production activity of ~20 mmol h−1g−1, that is 2 and 20 times greater than the benchmark Au/CdS and pristine CdS photocatalysts, respectively. Detailed analyses based on UV–Visible diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), steady state photoluminescence (PL) and energy dispersive spectroscopy (EDS) suggested cocatalysts Cu/Ni hydroxides were transformed into their metallic states during photoreaction. Cu° was produced by the transfer of electrons due to the as available position of CdS conduction band (E°=0.61 V) to surface Cu(OH)2 nanoclusters (Cu(OH)2/Cu°, E°= 0.224 V) whereas Ni° was produced by the shift in conduction band level of CdS under continuous sunlight illumination (Ni(OH)2/Ni°, E°= 0.72 V). Based on these observations, the mechanism of hydrogen production from water splitting over Cu/Ni(hydroxides)-CdS was described.

Potential of Scenedesmus-fabricated ZnO nanorods in photocatalytic reduction of methylene blue under direct sunlight: kinetics and mechanism.

Organic synthetic dyes are widely used in several industries; however, their inherent resistance to biodegradation necessitates to investigate alternative methods for the remediation of this class of hazardous substances. In the present study, a green synthesis of ZnO nanorods was achieved in a fast, environment-friendly, and safe microwave process employing algal extract. Different metabolites like sugars, proteins, fatty acids, amino acids, and vitamins present in the algal extract reduced the Zn2+ into ZnO. The XRD analysis showed that the nanostructure was a crystalline hexagonal nanorod having a crystalline size of 27.37 nm. The XPS spectra of ZnO nanorod showed characteristic peaks at binding energy 1043, 1020, 496, 137, 87, and 8 eV corresponding to Zn2p1/2, Zn2p3/2, ZnLMM, Zn3s, Zn3p, Zn3d, respectively. The synthesized ZnO nanorods were in-situ functionalized and showed strong catalytic activity in photoreduction of a model organic dye methylene blue (MB) under direct sunlight irradiation. Synthesized ZnO nanorods showed a complete (100%) reduction of model dye MB from its 10 mg/L aqueous solution. The photocatalytic degradation of MB followed the Michaelis-Menten kinetics. The rate of ZnO-catalyzed photocatalytic degradation depends on the concentrations of ZnO, pH, and sunlight irradiation. The ZnO nanorod-catalyzed photoreduction of MB involves hydroxyl radicals. Algal-mediated and microwave-assisted synthesis provides a scalable source of metal oxide nanoparticles for the remediation of dye-containing wastewaters under natural sunlight. Apart from application in the removal of dyes, ZnO nanorods are excellent material for applications in semiconductors, electronics, optics, bio-imaging, and drug delivery.

Structural and optical behavior of SnS2/NiFe2O4 NCs prepared via novel two-step synthesis approach for MB and RhB dye degradation under sun light irradiation

The present investigation focuses on facile two-step synthesis approach fabrication of tin sulfide (SnS2)/ nickel ferrite (NiFe2O4) nanocomposites (NCs) for the first time. The crystallinity and phase purity of the prepared material was investigated in powder X-ray diffraction (PXRD) studies. The presence of functional groups (stretching and bending vibration) was primarily determined by the Fourier Transform Infrared Spectroscopy (FT-IR) analysis. As well as, optical behavior of the synthesized samples was determined in UV–Vis absorption spectroscopic studies, and the presence of surface defects was established by PL spectroscopic studies. From the FESEM analysis, sponge-like structure was attained and Ni, Fe, Sn, S and O elemental component was determined by the EDAX spectrum analysis. The as-prepared SnS2/NiFe2O4 NCs exhibit superior photocatalytic performance and high stability toward the reduction of methylene blue (MB) and rhodamine B (RhB) dyes under irradiation of direct sunlight. The synthesized nanocomposites showed an efficient photocatalytic activity with a high reaction kinetic rate.

SnS/LDPE Composite: A reusable floating photocatalyst for solar degradation of organic dyes

Stable and reusable floating photocatalysts are highly sought-after for the complete utilization of the solar radiation in real industrial waste water treatment. Solar radiation responsive low-density polyethylene (LDPE)/SnS composite floating photocatalysts were prepared by embedding 20 wt% to 50 wt% of SnS nanoparticles into LDPE matrix. The photocatalytic activities of the composites were examined for the degradation of Methylene blue (MB) dye under direct sunlight irradiation with no mechanical stirring and oxygenation. The composite with 40 wt% SnS in LDPE, with a density of 1.005 g cm−3 partially submerged and showed superior degradation efficiency of 93% by facilitating efficient illumination and oxygenation. The near floating nature of the 40 wt% SnS/LDPE composite makes it of a great advantage for easy recollecting and re-using in actual waste water treatment of dying industry. The optical microscopy revealed discontinuous-porous structure for the composite with higher wt.% of SnS, causing increased active surface area. Incorporation of 20 wt% of Fe3O4 into SnS/LDPE composite makes the catalyst magnetically separable. Photocatalytic activity of novel SnS with cubic crystal structure is also tested. FTIR analysis of MB revealed the catalytic activity of SnS/LDPE composite and reaction path of dye degradation. The developed photocatalysts are stable and their photocatalytic activity was found to be sustained after five consecutive runs. The studied catalytic material will have real practical application in treating dyeing industry waste water economically by using low-cost SnS and naturally available solar radiation.

Sun light driven photocatalytic performance of Ag decorated TiO2 nanocomposite thin films by sol gel method

High performance, low cost photocatalysts are essential for water treatment applications. However the existing majority of the photocatalysts limited to Ultra violet and visible region only. Besides the fabrication of photocatalysts, there is a huge demand for low cost, recyclable and solar light trapping photocatalysts, thereby effectively remove the organic pollutants present in water. Here, we have synthesized the solar light active Ag loaded TiO2 nanocomposite thin films by sol gel method. X ray diffraction, scanning electron microscopy and UV–visible spectroscopy were applied to characterizing the product. The results show that we successfully synthesized the silver doped titanium dioxide thin films. The silver doped titanium dioxide thin films show red shift and broad absorption band in the whole UV visible region in comparison with bare titanium dioxide. The results show that the Ag-TiO2 nanocomposite exhibit best photocatalytic efficiency under direct sun-light irradiation due to increased electron transfer and charge separation. The photodegradation activities of the Ag doped TiO2 were studied with model organic pollutants. Ag doped TiO2 sample showed 98% degradation efficiency in just 70 min under sun light irradiation. Repeated cycle runs revealed that these catalysts exhibit reusability and excellent stability, able to trap solar light efficiently and suitable for degradation of many organic pollutants. The performances of the Ag-TiO2 nanocomposites indicate that, these catalysts can find potential applications in photocatalytic water treatment plants.

Assembly of mixed Bi4V1.4Nb0.6O11 phase and g-C3N4 photoactive material over rGO: Enhanced organic model pollutants removal under sun light irradiation

A novel efficient Bi4V1.4Nb0.6O11/g-C3N4 over the rGO ternary composite has been prepared by the cost effect method for diverse model organic molecule pollutants removal. The synergistic interaction between the materials has been investigated by the several characterization tools. The intimate contact between the ternary materials was explored by HRTEM analysis. The photo-catalytic degradation rate of the obtained ternary composite samples was examined for the removal of the MB dye and photo-reduction of the 4-Nitrophenol molecules in direct sun light irradiation. More interestingly, photo removal efficiency for MB molecule was achieved 93 % and the photo-reduction efficiency was 97 % for 4-Nitrophenol solution. The complete mineralization of the MB and 4-NP was further assessed by the LC-MS analysis, which shows the successful destruction of toxic molecules. The Z- scheme charge carrier transfer between the active materials was proposed and which is evidenced by the free radical trapping experiments and ESR trapping experiments.

Polydopamine functionalized graphene sheets decorated with magnetic metal oxide nanoparticles as efficient nanozyme for the detection and degradation of harmful triazine pesticides

A facile and an eco-friendly reduction and functionalization of reduced graphene oxide (rGO) sheets is carried out using dopamine and decorated with magnetic Fe3O4 nanoparticles with an average size of 12 nm by a simple co-precipitation method which is established as an artificial nanozyme. Here, functionalization of graphene using dopamine has introduced several advantages and insights into this study. The Fe3O4 nanoparticles decorated functionalized rGO sheets (FDGs) nanozymes are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, atomic force microscopy (AFM), thermogravimetric (TGA) and vibrating sample magnetometer (VSM) analysis. FDGs nanozymes exhibits dual characteristics towards detection and degradation of harmful simazine pesticide. The hydrogen bonding interactions between pesticide molecules and 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB) causes inhibition of the catalytic activity of the FDGs towards oxidation of TMB molecule. Based on that, the presence of simazine pesticide in an aqueous medium can be easily determined and a certain value (2.24 μM) of detection limit was achieved. The photocatalytic degradation of simazine is also executed and excellent photocatalytic activity was observed under irradiation of direct natural sunlight. The FDGs nanozyme is also reusable up to several times with insignificant loss in its catalytic activity towards simazine degradation.