UV-visible Illumination Research Articles

Flower-like nickel oxide nanostructures: Superior ammonia gas sensing and efficient dye removal behavior under UV–visible light illumination

In this study, we fabricated the NiO nanostructures using a straightforward solvothermal technique. The NiO nanoparticles were characterized using various analytical techniques. The FESEM images clearly show the flower-like structure of NiO nanoparticles. These nanostructures were then employed as a sensor to detect the presence of highly toxic ammonia (NH3) gas. The flower-shaped nanostructures of NiO played a vital role in improving sensing performance. Moreover, the NiO sensor displayed rapid response to 100 ppm ammonia at room temperature, with responses/recovery times of 40 s/44 s. This research holds promise as a viable approach for effectively sensing and detecting NH3 gas. The NiO exhibited excellent photocatalytic activity and degradation rates of 80% and 84.75% for Methyl orange (MO) and methylene blue dye (MB) respectively under UV-visible light irradiation. The NiO nanoflower remains unaffected after recycling MB dye degradation. This effective photocatalytic performance might be due to the formation of flower-like morphology. This underscores the potential of NiO as a promising candidate for applications in environmental and healthcare safety applications.

Catalytic photo-degradation of brilliant green and bacterial disinfection of Escherichia coli by the action of Y2Ti2O7/AgO films

In this study, we evaluated the photocatalytic efficacy of pure Y2Ti2O7 films incorporating varying AgO ratios (1.0, 3.0, and 5.0 mol%) in the degradation process of brilliant green dye and in the bacterial disinfection of Escherichia coli under UV–visible illumination. The films were prepared utilizing a photochemical methodology involving β-diketonate complexes of Y(dbm)3, Ti(dbm)4, and Ag(acac) as starting materials. Following synthesis, the photo-deposits underwent calcination at 900 °C for 2 h and were subsequently analyzed using Fourier Transform Infrared Spectroscopy, X-Ray diffraction, Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy, and X-ray Photoelectron Spectroscopy. The outcomes of these characterizations indicate the formation of a pyrochlore Y2Ti2O7 cubic phase, with the emergence of AgO in the doped samples. Photocatalytic performance yielded significant results, with a 94.9 % degradation of brilliant green observed for Y2Ti2O7 samples doped at 3.0 mol%, and a 98.4 % inhibition of Escherichia coli cultures observed for Y2Ti2O7 samples doped at 1.0 mol%. Theoretical calculations were employed to determine the band edge potentials of both oxides, supporting the establishment of a type I heterojunction between the Y2Ti2O7 phase and AgO. A degradation mechanism has been postulated based on assays involving the blocking of reactive oxygen species and charge carriers through the use of specific inhibitors.

Exploring the photocatalytic degradation of organic textile dye using hydrothermally synthesized Ce-doped metal chalcogenide nanomaterial

The advancement of economical, facile and non-toxic approaches towards waste water treatment is a promising research area currently among scientific community. In this regard photocatalysis has specifically received significant attention due to its application in the eradication of toxic elements from wastewater. Hence, in the present study Ce-doped FeSe2 photocatalysts were prepared employing the simple, inexpensive and ecofriendly hydrothermal method. The prepared Ce-FeSe2 nanomaterial was subjected to different characterization techniques like x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), Cyclic Voltammetry (CV) and UV–visible spectroscopy to explore the characteristic properties of the prepared nanomaterials. XRD results revealed good crystallinity and purity of all synthesized Ce-FeSe2 nanomaterials. Surface morphology and elemental composition of the prepared nanomaterials was determined by FE-SEM and EDS spectroscopy. UV-Visible spectroscopy was used to explore the optical characteristic of the prepared photocatalysts. The results of optical absorption spectrum confirmed that increasing dopant percentage shows an improvement towards optical properties. The photocatalytic ability of the prepared Ce-FeSe2 nanomaterials was examined against the potentially toxic industrial dyes like Rhoadmine B (RB). The photocatalytic results show that 95.21% of dye degradation was exhibited by 7% Ce- doped FeSe2 nanomaterial under UV-visible light illumination duration of 120 min. Findings of the photocatalytic degradation process fitted well with pseudo first order reaction kinetics for RB dye.

Construction of 1D/2D core-shell structured K6Nb10.8O30@Zn2In2S5 as S-scheme photocatalysts for cocatalyst-free hydrogen production

Constructing heterostructures is an effective strategy to achieve efficient photocatalysis. The determination of the heterojunction types depends on the photo-induced charge carrier transfer path. Therefore, understanding the charge carrier transfer mechanism of heterojunctions plays an irreplaceable role in guiding the construction of rational heterojunctions. However, it is challenging due to the microscopic nature of charge carrier transfer. Herein, an S-scheme K6Nb10.8O30@Zn2In2S5 (KNbO@ZIS) heterojunction with 1D/2D core-shell structure is designed for improving photocatalytic hydrogen production. KNbO@ZIS exhibits a greatly improved cocatalyst-free hydrogen generation activity (12.35 mmol h−1 g−1) compared to K6Nb10.8O30 (KNbO) and Zn2In2S5 (ZIS) under UV–visible illumination. The improvement of photocatalytic performance is mainly attributed to the suppressed recombination of photogenerated charge carriers by the S-scheme heterojunction. The 1D/2D core-shell structure further accelerates the charge carrier transfer in the photocatalysts. S-scheme heterojunction mechanism is also demonstrated by ex/in situ irradiated X-ray photoelectron spectroscopy and Kelvin probe force microscopy measurements as well as work function calculations. This work provides a powerful strategy for designing novel heterojunction composites.

Investigating the Performance of Lithium-Doped Bismuth Ferrite [BiFe1−xLixO3]-Graphene Nanocomposites as Cathode Catalyst for the Improved Power Output in Microbial Fuel Cells

In this study, multifunctional lithium-doped bismuth ferrite [BiFe1−xLixO3]-graphene nanocomposites (x = 0.00, 0.02, 0.04, 0.06) were synthesized by a sol-gel and ultrasonication assisted chemical reduction method. X-ray diffraction and FESEM electron microscopy techniques disclosed the nanocomposite phase and nanocrystalline nature of [BiFe1−xLixO3]-graphene nanocomposites. The FESEM images and the EDX elemental mapping revealed the characteristic integration of BiFe1−xLixO3 nanoparticles (with an average size of 95 nm) onto the 2D graphene layers. The Raman spectra of the [BiFe1−xLixO3]-graphene nanocomposites evidenced the BiFe1−xLixO3 and graphene nanostructures in the synthesized nanocomposites. The photocatalytic performances of the synthesized nanocomposites were assessed for ciprofloxacin (CIP) photooxidation under UV-visible light illumination. The photocatalytic efficiencies of [BiFe1−xLixO3]-graphene nanocomposites were measured to be 42%, 47%, 43%, and 10%, for x = 0.00, 0.02, 0.04, 0.06, respectively, within 120 min illumination, whereas the pure BiFeO3 nanoparticles were 21.0%. BiFe1−xLixO3 nanoparticles blended with graphene were explored as cathode material and tested in a microbial fuel cell (MFC). The linear sweep voltammetry (LSV) analysis showed that the high surface area of BiFeO3 was attributed to efficient oxygen reduction reaction (ORR) activity. The increasing loading rates of (0.5–2.5 mg/cm2) [BiFe1−xLixO3]-graphene composite on the cathode surface showed increasing power output, with 2.5 and 2 mg/cm2 achieving the maximum volumetric power density of 8.2 W/m3 and 8.1 W/m3, respectively. The electrochemical impedance spectroscopy (EIS) analysis showed that among the different loading rates used in this study, BiFeO3, with a loading rate of 2.5 mg/cm2, showed the lowest charge transfer resistance (Rct). The study results showed the potential of [BiFe1−xLixO3]-graphene composite as a cost-effective alternative for field-scale MFC applications.

Ni2P-Modified P-Doped Graphitic Carbon Nitride Hetero-Nanostructures for Efficient Photocatalytic Aqueous Cr(VI) Reduction

Targeting heterostructures with modulated electronic structures and efficient charge carrier separation and mobility is an effective strategy to improve photocatalytic performance. In this study, we report the synthesis of 2D/3D hybrid heterostructures comprising P-doped graphitic carbon nitride (g-C3N4) nanosheets (ca. 50–60 nm in lateral size) and small-sized Ni2P nanoparticles (ca. 10–12 nm in diameter) and demonstrate their prominent activity in the photocatalytic reduction of Cr(VI). Utilizing a combination of spectroscopic and electrochemical characterization techniques, we unveil the reasons behind the distinct photochemical performance of these materials. We show that Ni2P modification and P doping of the g-C3N4 effectively improve the charge-carrier transportation and spatial separation through the interface of Ni2P/P-doped g-C3N4 junctions. As a result, the catalyst containing 15 wt.% Ni2P exhibits superior photocatalytic activity in the detoxification of Cr(VI)-contaminated effluents under UV-visible light illumination, presenting an apparent quantum yield (QY) of 12.5% at 410 nm, notably without the use of sacrificial additives. This study marks a forward step in understanding and fabricating cost-effective photocatalysts for photochemical applications.

Preparation of switchable thermo- and photo-responsive polyacrylic nanocapsules containing leuco-dye and spiropyran: Multi-level data encryption and temperature indicator

The fabrication of multi-level anti-counterfeiting inks with fast and enhanced reversibility and reasonable photofatigue resistance is a challenging issue nowadays. Smart capsules with nanometric size will facilitate their stimulation with enhanced responsivity and optical features. Herein, thermo- and photo-switchable dual-chromic nanocapsules were prepared through miniemulsion polymerization of methyl methacrylate together with simultaneous encapsulation of the synthesized leuco-dye derivative (STC) and hydroxyl-functionalized spiropyran (SPOH) with bisphenol A and 1-tetradecanol (TDH) or 1-dodecanol (DDH). The obtained capsules containing TDH (TPL@T) and DDH (TPL@D) showed spherical morphology with nanometric size in the range of 90–120 nm. Enthalpy and gravimetry analyses revealed more than 88 % (for the solvent) and 91 % (for total core materials) have been embedded into the nanocapsules, respectively. Simultaneous encapsulation of SPOH beside STC moieties induced a synergistic effect on thermochromic efficiency with 1.8-to-2.3-fold enhancement. Moreover, multiple responsivities were observed by UV–visible illumination with subsequent color change from colorless to purple and purple to yellow according to reflectance peak displacements. This makes them suitable for producing inks with multi-level data safety and anticounterfeiting. The coated TPL@D and TPL@T nanocapsules on cellulose substrate showed thermo-switchable color changes between deep red and colorless, introducing appropriate candidates for portable temperature indicators. Reversible thermo- and photo-responsivity of the printed pattern over 10 heating–cooling and UV–vis cycles exhibited their potentiality in anticounterfeiting multi-level data encryption.

Multifunctional Cu2SnS3 Nanoparticles with Enhanced Photocatalytic Dye Degradation and Antibacterial Activity.

We present a simplistic, ultrafast, and facile hydrothermal deposition of ternary Cu2SnS3 nanoparticles (CTS NPs). The fabricated CTS NPs show superior antimicrobial and photocatalytic activities. In the presence of UV-Visible illumination, methylene blue (MB) dye was studied for photocatalytic dye degradation activity of CTS NPs. Excellent efficiency is shown by incorporating CTS NPs to degrade MB dye. There is a ~95% decrease in the absorbance peak of the dye solution within 120 min. Similarly, CTS NPs tested against three bacterial strains, i.e., B. subtilis, S. aureus, P. vulgaris, and one fungal strain C. albicans, defining the lowest inhibitory concentration and zone of inhibition, revealed greater antimicrobial activity. Hence, it is concluded that the CTS NPs are photocatalytically and antimicrobially active and have potential in biomedicine.

Z-scheme heterojunction ZnSnO3/rGO/MoS2 nanocomposite for excellent photocatalytic activity towards mixed dye degradation

In this work, a novel (ZnSnO3/rGO/MoS2) nanocomposite was prepared and its photocatalytic performances were investigated. The synthesised ZnSnO3 spheres were well dispersed over the surface of rGO sheet and MoS2 layers (ZSGM). The structural, morphological and elemental properties of the composites were examined by XRD, SEM, HRTEM and EDS. The surface chemical composition and functional groups of the elements interlinked in the composites were identified from XPS and FTIR analysis. BET and Raman analysis indicate the effective formation between MoS2/rGO/ZnSnO3 ternary heterostructure nanocomposite. The suppressed photogenic charge carrier's recombination rate was investigated by PL analysis. From UV analysis, the bandgap of ZSGM nanocomposite was successfully tuned from 3.13 eV to 2.70 eV, leading to high photocatalytic performance by mixed dye pollutant under UV-visible light illumination. The ZSGM photocatalyst achieved highest removal rate of 0.0131 min−1 for Rh B degradation, and 0.0153 min−1 for MB dye degradation and efficiency was 78% (Rh B) and 86% (MB), respectively in 100 min, which shows dramatically enhanced activity than other samples. In the presence of rGO/MoS2 in ZS, ZSGM photocatalysts exhibit higher catalytic activity due to a lower bandgap, more absorption in the visible region, and suppressed recombination rate of photogenerated e−/h+ pairs.

Enhanced photocatalytic activity with metal ion doping and co-doping in CeO2 nanoparticles

In the present work effect of Yttrium (Y) and Zinc (Zn) doping and co-doping on the structural and optical properties of CeO2 are studied to evaluate its photocatalytic activity for the removal of crystal violet dye. A series of Y (2–10 mol %) and Zn (2–10 mol %) doped CeO2 are synthesized via co-precipitation route. The synthesized samples were characterized via X-ray diffraction, Transmission electron microscopy, Energy Dispersive X-ray analysis, Fourier transform infrared spectroscopy and Raman spectroscopy. The presence of different functional groups are studied via FTIR and Raman spectroscopy. XRD results confirmed the formation of cubic fluorite structured CeO2 with average crystallite size ∼ 3–7 nm. Y doping in CeO2 resulted an increase in the crystallite size, whereas Zn led to decrease in the crystallite size. The photocatalytic activity is studied via UV–visible spectroscopy technique by examining the absorbance spectra. Among the various samples, 8 mol % Y-doped CeO2 exhibited 100% degradation efficiency within 7 h, while 8% Zn-doped CeO2 exhibited 100% degradation efficiency towards crystal violet (CV) dye within 5 h under UV–visible illumination. In case of Y, Zn co-doped CeO2 samples, 100% degradation efficiency towards CV dye was achieved within 3 h under UV–visible light. The present study shows that the metal ion co-doping can lead to enhancement in the degradation efficiency by several folds as compared to doped samples.

EFFECT OF GOLD MODIFICATION ON THE PROPERTIES AND PHOTOACTIVITY OF Fe3O4/SiO2/TiO2 IN THE DEGRADATION OF NITROBENZENE

Efficient gold-modified-Fe3O4/SiO2/TiO2 photocatalysts have been synthesized and employed for nitrobenzene degradation under UV-visible illumination. The results revealed that the prepared Fe3O4/SiO2/TiO2-Au photocatalysts displayed magnetic properties. In addition, the modification of Au reduced the energy of the band gap of the photocatalyst, increased the responsiveness of TiO2 to visible light, and enhanced the photoactivity for nitrobenzene degradation. The optimum photocatalytic activity was obtained when 4% of Au was added to Fe3O4/SiO2/TiO2. The photodegradation percentages of 20 mg/L of nitrobenzene using Fe3O4/SiO2/TiO2-Au 4%, at pH 7 for 75 min under UV and visible light were 94.2% and 93.16%, respectively.

CeO2 supported Zn1-xMnxS (x: 0.025, 0.05, 0.075 and 0.10) catalyst for photoremoval of rhodamine B dye

Present work provides a detailed study of enhanced photocatalytic performance of CeO2 coupled Mn-doped ZnS nanoparticles. In a systematic study, undoped and Mn− doped (2.5, 5, 7.5 and 10 mol%) ZnS nanoparticles were synthesized using co-precipitation method. Then, using synthesized samples, heterostructure samples (ZnS/CeO2) were prepared by hydrothermal route. Successful incorporation of Mn ions in ZnS lattice was determined by X-ray diffraction, transmission electron microscopy and Fourier-transform infrared spectroscopy. Optical spectroscopies revealed the associated optical modifications because of Mn-doping and confirmed CeO2 attachment. The specific surface area calculated from N2 sorption isotherms suggested the mesoporous structure of the samples. Rhodamine B (RhB) dye was used to understand the structural modifications of both components for the photocatalytic performance under different radiations. It was observed that hydroxyl radicals (OH∙) were responsible for photo-oxidation of RhB molecule with excellent photostability of synthesized heterostructure sample under UV–visible illumination. To prove photocatalytic activity of catalysts under visible light, additional experiments with the use of vancomycin antibiotic, which do not absorb visible light, were performed. Though Mn doping improves the recombination rate of charge carriers of host ZnS, the attachment of CeO2, not even reduces the optical bandgap (red shift) but contributes to better separation of the photo-excited charge carriers in heterostructure catalysts.

Influence of anatase-brookite composition on photocatalytic degradation of diethyl phthalate

Considering the present situation of exploitation of TiO2 as a photocatalyst, optimization of its polymorphs (anatase, brookite, and rutile) becomes critical. In the present study, TiO2 nanoparticles have been synthesized using the sol-gel technique to understand the effect of heat treatment-induced anatase-brookite composition on photocatalytic diethyl phthalate removal. The influence of heat treatment on structural characteristics of TiO2 is investigated by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). Bot, XRD and Raman results indicated the coexistence of brookite and anatase. At the same time, UV–visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL) revealed the optical modifications caused by the presence of brookite in the anatase network to alter the photo absorption and photoemission characteristics. The photocatalytic degradation of diethyl phthalate was observed as 95 % under UV–visible illumination (for 225 min) in the presence of the sample, calcined at 200 °C.

Ultrasonically modified P25-TiO2 /In2O3 heterostructured nanoparticles: An efficient dual- responsive photocatalyst for solution and gas phase reactions

BackgroundDesigning and fabricating an efficient heterostructured photocatalyst for degrading organic pollutants is a major concern for environmental remediation researchers. In that series we fabricated a P25-TiO2/In2O3 (PT/In) heterostructured nanocomposite via the facile ultrasonication and sol-gel synthesis method. MethodsIn both solution and gas-phase methods, the photocatalytic efficiency of the obtained PT/In nanocomposite was investigated. DRIFT-IR was measured at room temperature with the effect of adsorbed ethanol molecules, which would be used as a different approach to confirm the photocatalytic reaction mechanism. Significant FindingsUnder UV-Visible light illumination, the PT/In-4 nanocomposite was found to be an excellent photocatalyst for degrading Acid Blue (AB) dye. The calculated degradation rate constant (k) of PT/In-4 was 4.0 × 10−2 min−1, which was 13.3 and 5.7 times higher than that of PT-4 (0.3 × 10−2 min−1) and bare In2O3 (0.7 × 10−2 min−1) materials, respectively. The enhancement in photocatalytic performance is owing to the synergistic effect of the heterojunction between TiO2 and In2O3 and a reduction in the recombination rate. Furthermore, the PT/In-4 nanocomposite showed high stability even after five consecutive cycles. The photocatalytic mechanism was proposed based on experimental results obtained through the gas phase photocatalytic studies via DRIFT-IR technique.

Tuning the Electronic Bandgap of Graphdiyne by H‐Substitution to Promote Interfacial Charge Carrier Separation for Enhanced Photocatalytic Hydrogen Production

AbstractGraphdiyne (GDY), which features a highly π‐conjugated structure, direct bandgap, and high charge carrier mobility, presents the major requirements for photocatalysis. Up to now, all photocatalytic studies are performed without paying too much attention on the GDY bandgap (1.1 eV at the G0W0 many‐body theory level). Such a narrow bandgap is not suitable for the band alignment between GDY and other semiconductors, making it difficult to achieve efficient photogenerated charge carrier separation. Herein, for the first time, it is demonstrated that tuning the electronic bandgap of GDY via H‐substitution (H‐GDY) promotes interfacial charge separation and improves photocatalytic H2 evolution. The H‐GDY exhibits an increased bandgap energy (≈2.5 eV) and exploitable conduction band minimum and valence band maximum edges. As a representative semiconductor, TiO2 is hybridized with both H‐GDY and GDY to fabricate a heterojunction. Compared to the GDY/TiO2, the H‐GDY/TiO2 heterojunction leads to a remarkable enhancement of the photocatalytic H2 generation by 1.35 times under UV–visible illumination (6200 µmol h−1 g−1) and four times under visible light (670 µmol h−1 g−1). Such enhancement is attributed to the suitable band alignment between H‐GDY and TiO2, which efficiently promotes the photogenerated electron and hole separation, as supported by density functional theory calculations.

Rapid hydrothermal synthesis of highly crystalline transition metal (Mn & Fe) doped CuSe nanostructures: Applications in wastewater treatment and room temperature gas sensing

In this paper, we report on the rapid hydrothermal synthesis of CuSe 2D nanocrystals. The nanostructures were synthesized for very short reaction durations of 3 h. The influence of two different transition metal inclusions (Mn & Fe) on the growth and properties of CuSe nanocrystals was investigated. Transition metal dopants were found to have a prominent influence on the morphological, magnetic, optical and photocatalytic behavior of the material. Structural properties show that the nanostructures have a single phase with the hexagonal structure. The inclusion of the transition metal dopants (Mn and Fe) had no influence on the phase of the nanostructures although growth along certain crystal directions was restricted. Morphologies like flakes and hexagonal discs were obtained, all in the nanoscale dimensions. Doping resulted in the development of catalytically active edge sites which are more prominent in the case of Fe doping. Magnetic studies reveal conversion of diamagnetic CuSe into paramagnetic material upon doping with Fe and Mn. The gas sensing property of the synthesized nanostructures was tested against NO2 gas. The hexagonal nano-discs showed the highest sensitivity reaching 25% at 40 ppm NO2 concentration. The nanostructures were utilized for the photodegradation of methylene blue (MB) dye under UV-Visible light illumination. Addition of the transition metal dopants resulted in the enhancement of photocatalytic activity of the material, improving the degradation percentage from 59.4% to 64.5%.

Bacterial Nanocellulose/MoS2 Hybrid Aerogels as Bifunctional Adsorbent/Photocatalyst Membranes for in-Flow Water Decontamination.

To address the problems associated with the use of unsupported nanomaterials, in general, and molybdenum disulfide (MoS2), in particular, we report the preparation of self-supported hybrid aerogel membranes that combine the mechanical stability and excellent textural properties of bacterial nanocellulose (BC)-based organic macro/mesoporous scaffolds with the excellent adsorption-cum-photocatalytic properties and high contaminant removal performance of MoS2 nanostructures. A controlled hydrothermal growth and precise tuning of the synthetic parameters allowed us to obtain BC/MoS2-based porous, self-supported, and stable hybrid aerogels with a unique morphology resulting from a molecular precision in the coating of quantum-confined photocatalytic MoS2 nanostructures (2-4 nm crystallite size) on BC nanofibrils. These BC/MoS2 samples exhibit high surface area (97-137 m2·g-1) and pore volume (0.28-0.36 cm3·g-1) and controlled interlayer distances (0.62-1.05 nm) in the MoS2 nanostructures. Modification of BC with nanostructured MoS2 led to an enhanced pollutants removal efficiency of the hybrid aerogels both by adsorptive and photocatalytic mechanisms, as indicated by a detailed study using a specifically designed membrane photoreactor containing the developed photoactive/adsorptive BC/MoS2 hybrid membranes. Most importantly, the prepared BC/MoS2 aerogel membranes showed high performance in the photoassisted in-flow removal of both organic dye (methylene blue (MB)) molecules (96% removal within 120 min, Kobs = 0.0267 min-1) and heavy metal ions (88% Cr(VI) removal within 120 min, Kobs = 0.0012 min-1), separately and/or simultaneously, under UV-visible light illumination as well as excellent recyclability and photostability. Samples with interlayer expanded MoS2 nanostructures were particularly more efficient in the removal of smaller species (CrO42-) as compared to larger (MB) dye molecules. The prepared hybrid aerogel membranes show promising behavior for application in in-flow water purification, representing a significant advancement in the use of self-supported aerogel membranes for photocatalytic applications in liquid media.

Silver photodiffusion into amorphous Ge chalcogenides

Silver photodiffusion into amorphous chalcogenides involves the movement of ions controlled by a UV-visible light illumination, and has potential application to memory devices. Understanding the kinetics of this phenomenon will expand the range of possible applications. Herein, we report the excitation photon energy dependence of the silver photodiffusion kinetics in Ag/amorphous Ge20S80/Si substrate stacks, probed by neutron reflectivity using four light-emitting diodes with different peak wavelengths. Time-dependent changes were clearly observed in all three of the Ag/Ag-doped reaction/chalcogenide host layers, in terms of layer thickness, scattering length density, and roughness. Silver photodiffusion effectively occurred when the excitation photon energy was greater than the optical gap of the chalcogenide host material. Excitation of lone-pair electrons to anti-bonding states at the chalcogenide layer therefore appears to play a crucial role in triggering silver photodiffusion.

Green Synthesized Ag Nanoparticles for Bio-Sensing and Photocatalytic Applications.

In this work, sensing and photocatalytic activities of green synthesized silver nanoparticles (Ag NPs) are investigated. Ag NPs have been synthesized by the reduction of silver nitrate (AgNO3) using different leaf extracts. An optimum surface plasmon resonance (SPR) behavior is obtained for neem leaf extracts because of the presence of a high concentration of diterpenoids, as evidenced from gas chromatography mass spectroscopy results. The underlying mechanism for the formation of Ag NPs is highlighted. The Ag NPs are in spherical shape and exhibit the hexagonal crystal phase and also show a good stability. The biosensing property of the Ag NPs is evaluated using mancozeb (MCZ) agro-fungicide, and the SPR peak position exhibited a linear response with MCZ concentration. The sensitivity is found to be 39.1 nm/mM. Further, the photocatalytic activity of Ag NPs is tested using 0.5 mM MCZ solution as a model under UV–visible illumination. It is observed that photocatalytic activity is caused by the formation of reactive oxygen species. Therefore, the green synthesized Ag NPs are potential candidates for biosensing and photocatalytic applications.

In situ preparation of Bi2S3 nanoribbon-anchored BiVO4 nanoscroll heterostructures for the catalysis of Cr(vi) photoreduction

Novel Bi2S3 nanoribbon-anchored BiVO4 nanoscroll heterostructures were fabricated, showing enhanced photocatalytic activity for Cr(vi) reduction under UV-visible light illumination.