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A Biological-Based Photovoltaic Electrochemical Cell: Modelling the Impedance Spectra
摘要： The impedance response of an electrochemical cell able to convert sunlight into electrical power is analyzed and discussed. Light conversion is due to a photosynthetic system known as reaction center, which is the core of photosynthesis in several living beings. Under illumination, an abrupt transformation drives the cell electrical response from insulator to conductor and a photocurrent is observed. The impedance spectrum shows a peculiar shape which significantly modifies after the protein activation. It has been analyzed by means of a graphical/analytical/numerical procedure. Some impedance graphical representations are indicated as the most appropriate to suggest the design of an equivalent electrical circuit. Then, the analytical expression of this circuit is formulated and used to set-up a custom Phyton code useful for fitting experimental data. Finally, an appropriate normalization procedure is proposed, which validates data in dark and light and can be useful as a fast screening of measurements.
关键词： photo-electrochemical cell,reaction centers,impedance
更新于2025-09-23 15:19:57
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Prospects for Hermetic Sealing of Scaled-Up Photoelectrochemical Hydrogen Generators for Reliable and Risk Free Operation
摘要： Photo-electrochemical (PEC) systems have the potential to contribute to de-carbonation of the global energy supply because solar energy can be directly converted to hydrogen, which can be burnt without the release of greenhouse gases. However, meaningful deployment of PEC technology in the global energy system, even when highly e?cient scaled up devices become available, shall only be a reality when their safe and reliable operation can be guaranteed over several years of service life. The ?rst part of this review discusses the importance of hermetic sealing of up scaled PEC device provided by the casing and sealing joints from a reliability and risk perspective. The second part of the review presents a survey of fully functional devices and early stage demonstrators and uses this to establish the extent to which the state of the art in PEC device design address the issue of hermetic sealing. The survey revealed that current material choices and sealing techniques are still unsuitable for scale–up and commercialization. Accordingly, we examined possible synergies with related photovoltaic and electrochemical devices that have been commericalised, and derived therefrom, recommendations for future research routes that could accelerate the development of hermetic seals of PEC devices.
关键词： hermetic sealing,safety,photo-electrochemical,reliability,scale-up,solar hydrogen generator
更新于2025-09-16 10:30:52
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Mesoporous Tungsten Trioxide Photoanodes Modified with Nitrogen-Doped Carbon Quantum Dots for Enhanced Oxygen Evolution Photo-Reaction
摘要： Nanostructured photoanodes are attractive materials for hydrogen production via water photo-electrolysis process. This study focused on the incorporation of carbon quantum dots doped with nitrogen as a photosensitizer into mesoporous tungsten trioxide photoanodes (N-CQD/meso-WO3) using a surfactant self-assembly template approach. The crystal structure, composition, and morphology of pure and N-CQD- modi?ed mesoporous WO3 photoanodes were investigated using scanning electron and transmission microscopy, X-ray di?raction, and X-ray photoelectron spectroscopy. Due to their high surface area, enhanced optical absorption, and charge-carrier separation and transfer, the resulting N-CQD/meso-WO3 photoanodes exhibited a signi?cantly enhanced photocurrent density of 1.45 mA cm?2 at 1.23 V vs. RHE under AM 1.5 G illumination in 0.5 M Na2SO4 without any co-catalysts or sacri?cial reagent, which was about 2.23 times greater than its corresponding pure meso-WO3. Moreover, the oxygen evolution onset potential of the N-CQD/meso-WO3 photoanodes exhibited a negative shift of 95 mV, signifying that both the charge-carrier separation and transfer processes were promoted.
关键词： tungsten,dots,trioxide,photo-electrochemical,mesoporous,quantum,carbon,water splitting
更新于2025-09-11 14:15:04
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Green synthesized plasmonic nanostructure decorated TiO2 nanofibers for photoelectrochemical hydrogen production
摘要： We herein present the Au and Ag NPs synthesized via chemical reduction with green synthesized carbon nanolights (CNL) as a visible light photosensitizer for TiO2 nanofibers (TNFs) towards photoelectrochemical water splitting. The synthesized photoanodes (PA1: TNFs, PA2: Ag@CNLs/TNFs and PA3: Au@CNLs/TNFs) were probed ex-situ for morphological, structural, optical and electronic properties before being used for the PEC experiments. We first show the efficient photocatalytic activity of these photoanodes for the degradation of methylene blue under visible light irradiation. Followed by the photoelectrochemical (PEC) water splitting investigation, which reveals the substantially improved photocurrent density to 13 mA/cm2 and 18 mA/cm2, for PA2 and PA3, respectively under simulated AM 1.5 solar illumination at 1.36 V vs RHE, ~15 fold enhancement compared to that obtained for a PA1. This improvement we attributed to the synergic consequence, improved absorption and effective charge carrier separation & transport due to surface plasmonic effect, which is well evident in the decrease of measured charge transfer resistance (Rct), for PA2 (15.1 Ω) and PA3 (6.71 Ω), as compared to PA1 (139 Ω).
关键词： TiO2 nanofibers,Green synthesis,Hydrogen,Photo-electrochemical,Carbon quantum dots,Plasmonic nanostructures
更新于2025-09-11 14:15:04
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Recent Advances and Emerging Trends in Photo-Electrochemical Solar Energy Conversion
摘要： Photo-electrochemical (PEC) solar energy conversion offers the promise of low-cost renewable fuel generation from abundant sunlight and water. In this Review, recent developments in photo-electrochemical water splitting are discussed with respect to this promise. State-of-the-art photo-electrochemical device performance is put in context with the current understanding of the necessary requirements for cost-effective solar hydrogen generation (in terms of solar-to-hydrogen conversion efficiency and system durability, in particular). Several important studies of photo-electrochemical hydrogen generation at p-type photocathodes are highlighted, mostly with protection layers (for enhanced durability), but also a few recent examples where protective layers are not needed. Recent work with the widely studied n-type BiVO4 photoanode is detailed, which highlights the needs and necessities for the next big photoanode material yet to be discovered. The emerging new research direction of photo-electrocatalytic upgrading of biomass substrates toward value-added chemicals is then discussed, before closing with a commentary on how research on PEC materials remains a worthwhile endeavor.
关键词： value-added chemicals,hydrogen,photo-electrochemical,water splitting
更新于2025-09-09 09:28:46
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Electrochemical properties of the scheelite BaWO4 prepared by co-precipitation: Application to electro-photocatalysis of ibuprofen degradation
摘要： The scheelite BaWO4 elaborated by co-precipitation, is a wide band gap semiconductor crystallizing in the tetragonal symmetry. The oxide is identi?ed by X-ray di?raction and characterized by scanning electron microscopy and di?use re?ectance. The optical transition (2.95 eV) involves O2-: 2p orbital and W6+ eg: level, further direct transition occurs at 4.88 eV. The peaks in the Raman spectrum are assigned to symmetrical vibrations of tetragonal units [WO4]2-. The oxide shows an oxygen de?ciency and the conductivity follows a thermally activated hopping of lattice polaron with activation energy of 0.31 eV. The photo electrochemical analysis of BaWO4 at pH 5.5 gives a ?at band potential of 0.20 VSCE and electrons density of 1.8 × 1019 cm?3. The positive slope of the plot (capacitance?2 - potential) indicates n type conduction, a result con?rmed by chrono-amperometry. The frequency dispersion of the real/imaginary impedances is undertaken both in the dark and under illumination; the response is modeled by an equivalent circuit with a predominant bulk contribution. As application, the photo electrons in the conduction band (?0.11 VSCE) reduce oxygen into radicals O2?, allowing a partial mineralization of ibuprofen, one of the most consumed medicaments. The electro-photocatalysis i.e. combined electrocatalysis/electro-photocatalysis using TiPt as cathode and BaWO4 as anode (100 mA/25 V) shows a high conversion yield (75%), in aerated ibuprofen solution (20 ppm) in less than 6 h under UV light (12 mW cm?2). The reaction follows a pseudo-?rst order kinetic with a rate constant of 3.7 × 10?3 min?1, about twice higher than that obtained by electrocatalysis (50%, k = 1.9 × 10?3 min?1).
关键词： Electro-photocatalysis,Photo electrochemical,Scheelite BaWO4,UV light,Ibuprofen
更新于2025-09-09 09:28:46
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Efficient Modified Bimetallic Alloy Nanoparticles Porous Silicon Gas Sensors for CO Gas Detection Process
摘要： The influence of embedding Au, Pd monometallic and Au-Pd bimetallic nanoparticles on porous silicon-based gas sensor was investigated. Porous silicon layer P-si was prepared by photo electrochemical etching (PECE) with the laser wavelength of about 635 nm and 25 mW/cm2 laser power density. AuNPs/P-si, PdNPs/P-si and Au-PdNPs/P-si hetrostructures were prepared by ion reduction process, this made by dipping fresh P-si in the salt solution contain HAuCl4, PdCl2 and mixing solutions at ratio 1:1 for about (1.2, 5 and 2 min), respectively. Au NPs/P-si, Pd NPs/P-si and Au-Pd NPs/P-si were investigated by scanning electron microscopy (SEM), FTIR analysis, X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Efficient gas sensing process was recorded for modified porous silicon P-si gas sensor with smallest bimetallic Au-Pd nanoparticles size. Considerable improvement in sensitivity and temporal response were obtained for modified bimetallic alloy nanoparticles porous silicon compared with bare P-si and monometallic nanoparticles gas sensors due to the high specific surface area.
关键词： Sensitivity,Ion reduction process,Monometallic,Photo Electrochemical Etching (PECE),Bimetallic,CO gas
更新于2025-09-09 09:28:46
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Visible light induced H2 evolution on the hetero-junction Ag/NiO prepared by nitrate route
摘要： The photo-electrochemical study of the hetero-junction Ag/NiO (5/95 wt%) prepared in situ by nitrate route was investigated to assess its photoactivity for the hydrogen production upon visible light. The X-ray diffraction pattern shows narrow peaks of Ag and NiO. The direct optical gap of the sensitizer NiO (1.51 eV) is well matched to the solar spectrum. It acts as n-type semiconductor and the potential of its conduction band (?0.35 VSCE), determined from the capacitance measurement, is more negative than the H2O/H2 level (～?0.3 VSCE), yielding water reduction under visible light; the photoactivity peaks at pH ～ 13. The excited electrons are transferred to Ag clusters, to reduce water into gaseous hydrogen owing to the low H2-over-voltage (～160 μmol). A quantum conversion efficiency of 0.11% is reported under visible light (3.42 × 1018 photons s?1) within ～10 min with an evolution rate of 96 μmol h?1 mg?1. The catalyst was tested for several successive photocatalytic cycles, a de-activation effect of ～7% per cycle is observed, thus proving its stability and repeatability. The heating of the catalyst under dynamic vacuum at 250 °C restores the initial photoactivity.
关键词： Hetero-junction Ag/NiO,Hydrogen,Semiconductor,Photo-electrochemical
更新于2025-09-04 15:30:14