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Adsorption Dynamics of Redox Active Species onto Polarized Surfaces of Sensitized NiO
摘要： Mesoporous NiO films were deposited by means of a screen printing technique onto fluorine-doped tin oxide transparent electrodes and consequently sensitized with Erythrosin B (EryB) dye. The obtained colored NiO material was used as a working electrode in a three-electrode cell to study the evolution of the triple semiconductor/dye/electrolyte interface upon electrochemical polarization in dark conditions. The electrolyte was a solution of I3?/I? in acetonitrile, with the redox couple representing the typical redox shuttle of dye-sensitized solar cells (DSCs). The adopted electrochemical conditions were devised in order to simulate the actual electrical environment of the NiO/dye photocathode in a light-soaked DSC. The use of a benchmark sensitizer EryB and of the most widely used redox mediator I3?/I? is particularly meaningful for the study of the adsorption dynamics and the determination of possible degradative phenomena on the basis of the behavior of numerous analogue systems. Therefore, for the first time, the evolution of the NiO/EryB/I3?/I? multiple interface was investigated combining the electrochemical characterization with ex situ spectroscopic analysis by means of X-ray photoelectron spectroscopy. The resulting picture shows that EryB in the immobilized state promotes the redox processes based on the I3?/I? couple. Moreover, the EryB sensitizer inhibits the phenomena of recombination between the metal oxide semiconductor and the redox couple.
关键词： X-ray photoelectron spectroscopy,Sensitized NiO,Dye-sensitized solar cells,Redox active species,Adsorption dynamics,Polarized surfaces
更新于2025-09-23 15:22:29
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Electronic structure and UV–Vis spectra simulation of square planar Bis(1-(4-methylphenylazo)-2-naphtol)-Transition metal complexes [M(L)2]x (M?=?Ni, Pd, Pt, Cu, Ag, and x?=???1, 0, +?1): DFT and TD-DFT study
摘要： DFT/B3LYP calculations with full geometry optimizations have been carried out on 1-phenylazo-2-naphthol and their metal complexes of formula M(MePhNap)2 (M = Ni, Pd, Pt, Cu, Ag, and MePhNap = 1-(? 4-methylphenylazo)-2-naphtol) in their neutral, oxidized, and reduced forms. The predicted structures provide to the M(II) metal ions the square planar geometry and distorted azo ligand. The TD-DFT theoretical study performed on the optimized geometry allowed us to predict the UV–Vis spectra and to identify quite clearly the spectral position and the nature of the different electronic transitions according to their molecular orbital localization. Large HOMO-LUMO gaps are calculated for all optimized structures suggesting good chemical stabilities, hence, reproducing the available UV–Vis spectra and compared to that of free ligand. The electronic spectra obtained in DMSO and ethanol polar solvents predict more important red shifts than those obtained in hexane as nonpolar one.
关键词： Electronic transitions,Molecular orbital localization,Metal-ligand coordination,Azo dye
更新于2025-09-23 15:21:21
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Structural, optical and photocatlytic properties of zinc oxide nanoparticles obtained by simple plant extract mediated synthesis
摘要： We report a facile and inexpensive method to prepare zinc oxide nanoparticles with different particle size and shape using Achyranthes aspera and Couroupita guianensis leaf extracts as the reducing agent and zinc nitrate as a precursor. The prepared zinc oxide nanoparticles were analyzed by various characterization methods and obtained results evidently revealed that crystalline parameter, purity, optical absorption, band gap, particle size and shape of the ZnO nanoparticles significantly influenced by the type of leaf extract used as reducing agent. Further, photocatlytic activity study obviously demonstrates that prepared samples exhibits superior photocatlytic activity for the degradation of methylene blue dye by creating superoxide anion radicals and OH radicals under photonic irradiation. Hence, prepared zinc oxide nanoparticles by plant extract mediated synthesis can be applied as a photocatlyst for the possible waste water treatment in textile industry.
关键词： Waste water treatment,Photocatalytic activity,Plant extract mediated synthesis,Methylene blue dye,Zinc oxide nanoparticles
更新于2025-09-23 15:21:21
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Composition analysis of Ta <sub/>3</sub> N <sub/>5</sub> /W <sub/>18</sub> O <sub/>49</sub> nanocomposite through XPS
摘要： A characterization of a nanocomposite material consisting of Ta3N5 nanoparticles and W18O49 nanowires is presented. The material is of interest for photocatalytic applications, with a focus on pollution reduction through the photodegradation of dye waste; under white light illumination, the combination of Ta3N5 and W18O49 yielded an enhanced rate of dye degradation relative to Ta3N5 particles alone. The facile method of synthesis is thought to be a promising route for both upscale and commercial utilization of the material. X-ray photoelectron spectroscopy revealed a core–shell composite structure with W18O49 present as an overlayer on Ta3N5; the analyzed spectra for the C 1s, O 1s, Ta 4f, N 1s, W 4f, and Na 1s regions are reported. It should be noted that due to differential charging of the underlying Ta3N5 component relative to the W18O49 shell, an additional uncompensated voltage shift may exist in the Ta 4f and N 1s spectra.
关键词： x-ray photoelectron spectroscopy,XPS,dye degradation,W18O49,nanowires,composite,Ta3N5,photocatalysis
更新于2025-09-23 15:21:21
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Photoregeneration of Biomimetic Nicotinamide Adenine Dinucleotide Analogues via a Dye-Sensitized Approach
摘要： Two-step photochemical reduction of an acridinium-based cation 2O+ to the corresponding anion 2O? was investigated using a dye-sensitized approach involving 2O+?COOH attached to the surface of a wide-bandgap semiconductor, p-NiO. The cation 2O+ and corresponding one-electron reduced radical form, 2O? were synthesized and characterized using steady-state UV/vis and electron paramagnectic resonance spectroscopy. The thermodynamics for the photoinduced hole injection from 2O+ and 2O? were evaluated and found to be favorable. Subsequent femtosecond transient absorption spectroscopy was utilized to evaluate the photoinduced hole injection into NiO, starting from 2O+?COOH/NiO and 2O??COOH/NiO samples. The excitation of 2O+?COOH at 620 nm initiated fast (2.8 ps) hole injection into NiO. However, 90% of the charge-separated population recombined within ～40 ps, while ～10% of the charge-separated population exhibited lifetimes longer than the time scale of our instrument (1.6 ns). In the case of 2O??COOH/NiO, the light absorption occurs predominantly by NiO (2O??COOH absorbs at 310 nm) and is associated with the electron transfer from the conduction band of NiO to the radical. The charge-separated state in this case appears to be long-lived, based on the slow (ns) growth of the trapped carriers formed on the NiO surface. The results of this work indicate that the photochemical reduction of 2O+ to the corresponding hydride form (2OH) can be achieved, opening the possibility of using such a dye-sensitized approach for regeneration of nicotinamide adenine dinucleotide analogues in enzymatic and chemical catalysis.
关键词： multiple charge accumulation,stable radical,NADH,photochemistry,NiO,dye sensitization
更新于2025-09-23 15:21:21
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Dye-sensitized solar cell-thermoelectric hybrid generator utilizing bipolar conduction in a unified element
摘要： The dye-sensitized solar cell-thermoelectric hybrid generator (DS-TEG), which is a hybridization of a dye-sensitized solar cell (DSSC) and a thermoelectric generator (TEG) not at the structural level but in terms of material-level unification, is presented. The Pt-coated TE element provides electrons to the iodide/triiodide electrolyte to lower the redox barrier. This promotes the reduction of triiodide, resulting in a dramatic increase in the electron recombination lifetime. The available charge density, carrier diffusion coefficient and effective diffusion length were significantly increased when utilizing both types of carriers and acceleration in an iodide/triiodide reduction reaction in the unified DS-TEG.
关键词： Dye-sensitized solar cell,synergetic effect,dye-sensitized thermoelectric hybrid generator,thermoelectric element,triiodide reduction rate
更新于2025-09-23 15:21:01
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Highly Efficient Dye-sensitized Solar Cells with Composited Food Dyes
摘要： As a representative of third generation solar cells, dye-sensitized solar cell (DSSC) possesses advantages of easy fabrication and relatively high-power conversion efficiency (PCE). However, the commonly used dyes (such as N719, N3, C217, and Z907) in DSSCs are expensive and toxic. Herein, the non-toxic food dyes, including Amaranth, Sunset Yellow, and Erythrosin B, were explored for DSSC applications. Particularly, this is the first time to combine two of food dyes for DSSCs, leading to a remarkable increase of PCE. Furthermore, a correlation was identified between the PCE and the composition of combined dyes. The ZnO-based DSSC with combined Amaranth and Erythrosin B dyes exhibited the highest PCE of 2.64%.
关键词： Amaranth,Sunset Yellow,dye-sensitized solar cells,Erythrosin B,non-toxic food dye
更新于2025-09-23 15:21:01
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A computational study on boron dipyromethene ancillary acceptor-based dyes for dye-sensitized solar cells
摘要： A series of (D-π)2-An-A based organic dyes containing boron dipyrromethene (BODIPY) moiety as an ancillary acceptor (An) derivative were chosen, and the effect of donor moieties (diarylamine, carbazole, azepine, and dibenzazepine) was investigated to understand their photophysical and photoelectrochemical properties by employing density functional theory (DFT) and time-dependent DFT. It is experimentally proved that BODIPY enhances the light-harvesting in red and near IR region of visible light. The electron density distribution analysis was performed for all the dyes to confirm the intramolecular charge transfer, envisioned from the simulated absorption spectra of the dyes. Carbazole donor-based dye exhibited the lowest reorganization energy. A dye attached to the TiO2 (1 0 1) surface was modeled to estimate the adsorption energy of the dyes. The density of states analysis revealed that the absence of defect states in the bandgap of TiO2 facilitates the smooth electron transfer from the excited state of the dye to the conduction band of TiO2. Considering the lowest unoccupied molecular orbital (LUMO) energy level of dyes and conduction band energy level of TiO2, it is understood that all the dyes studied in this study are capable of electron injection upon photoexcitation. Considering the driving force for dye regeneration of the dyes and the magnitude of reorganization energy, carbazole donor-based dye (D2) would be the best performing dye in DSSC. Previously, the power conversion efficiencies of the dyes have been reported, and carbazole donor-based dye (D2) exhibited the highest efficiency among all the dyes. Our computational investigations are in good agreement with the experimental results.
关键词： TiO2 (1 0 1) surface,Reorganization energy,DSSC,Dye regeneration,BODIPY
更新于2025-09-23 15:21:01
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Controlled synthesis of CuO decorated defect enriched ZnO nanoflakes for improved sunlight-induced photocatalytic degradation of organic pollutants
摘要： We report synthesis and application of a unique heterojunction nanocomposite formed between copper nanoparticles (CNPs) and defect rich ZnO nanoflakes for application towards water remediation. Systemic variation in CNPs functionalization was seen to modulate the optical, structural and photocatalytic properties of the heterojunction, which were found to be well in accordance with the results from TEM, UV-DRS and EPR. The remediation ability of the heterojunction measured in terms of its photocatalytic ability was studied by degrading three different organic dye pollutants Rhodamine 6G (R6G), Methylene Blue (MB) and Methyl Orange (MO) using solar light (850 W/cm2) as the renewable excitation source. CNPs loading density was seen to follow a direct linear relationship to optical absorbance and band gap narrowing. The initial increase in photolytic efficiency is associated with improved visible light response and reduced band gap due to attachment of CNPs while reduction in activity was found to be associated with generation of self-recombination centres in CuO functionalization. Optimized CNP modified ZnO nanoflakes was able to decompose 10 μM of R6G, MB and MO dye solutions in 80, 40 and 60 min respectively.
关键词： Semiconductor,CuO,Photocatalysis,ZnO,Dye degradation
更新于2025-09-23 15:21:01
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Biomass-derived carbon boosted catalytic properties of tungsten-based nanohybrids for accelerating the triiodide reduction in dye-sensitized solar cells
摘要： Manganese tungstate (MWO), zinc tungstate (ZWO), and copper tungstate (CWO) embedded biomass-derived carbon (MWO-C, ZWO-C, CWO-C) was synthesized by hydrothermal treatment and investigated as counter electrode (CE) catalyst to test electrochemical activity. Biomass-derived carbon was used as the shape controlling agent, which changed the morphology of MWO from spherical to spindle-like. Owing to the synergistic effect between tungsten-based bimetal oxides and biomass-derived carbon, the MWO-C, ZWO-C, and CWO-C catalysts exhibited enhanced electrochemical performance in dye-sensitized solar cells (DSSCs) system. The MWO-C, ZWO-C and CWO-C catalysts in DSSCs showed outstanding power conversion efficiency (PCE) of 7.33%, 7.61%, and 6.52%, respectively, as compared with 7.04% for Pt based devices. Biomass-derived carbon improves the catalytic properties of tungsten-based nanohybrids. The results showed that biomass-derived carbon-enhanced inorganic compound as CE catalysts are promising alternatives to Pt-based CE catalysts for energy conversion devices.
关键词： Triiodide reduction reaction,Counter electrode catalyst,Biomass-derived carbon,Tungsten-based nanohybrids,Dye-sensitized solar cells
更新于2025-09-23 15:21:01