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Selective Activation of Benzyl Alcohol Coupled with Photoelectrochemical Water Oxidation via a Radical Relay Strategy
摘要： Selective oxidation to produce target chemicals usually need activation of O2 at high temperature and/or pressure, which have largely restricted its practical operation and application. Here, we put forward a radical-relay strategy coupling photoelectrochemical (PEC) water oxidation towards efficiently selective conversion of benzyl alcohol (BA) to benzaldehyde (BAD). An illuminated BiVO4 (BVO) photoanode covered with an ultrathin (~3 nm) hydrothermally synthesized layered double hydroxide (U-LDH) catalyst and graphene (G) exhibited >99% selectivity to BAD (1.2 V vs. RHE). Mechanistic studies and DFT calculation verified that the hydroxyl radicals (?OH) generated from the oxidation of water are bound to the surface of U-LDH through hydrogen-bonding interactions and the energy is lowered. Fourier transform infrared spectroscopy showed that BA is adsorbed to the U-LDH catalyst, but BAD is not. Thus, the selectivity is not only favored by the controlled oxidation capacity of ?OH radicals, but the desorption of the desired product from the catalyst before further oxidation occurs. This work introduces an alternative PEC way to achieve mild and selective oxidation of BA derivatives based on ternary G@U-LDH@BVO catalysts.
关键词： radical relay,ultrathin LDH,aromatic alcohols,PEC water oxidation,selective activation
更新于2025-09-23 15:21:01
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FTO-TiO2 photoelectrocatalytic degradation of triphenyltin chloride coupled to photoelectro-Fenton: A mechanistic study
摘要： A powerful, simple and stable transparent photoanode based on TiO2 nanoparticles deposited on fluorine-doped tin oxide (FTO) was synthesized for the photoelectrocatalytic degradation of the organometallic pollutant triphenyltin chloride (TPTCl). Contrasting with most of the works on photoelectrocatalysis (PEC), FTO-TiO2 was found to be an excellent anode material for the degradation/mineralization of organic pollutants at high anodic potentials through the formation of electrochemically-induced hVB+ (dark PEC), showing a similar behavior as the so-called 'non-active' anodes like the powerful boron doped diamond electrode (BDD). The electrocatalytic efficiency was enhanced by the photoexcitation of TiO2 under UV light (PEC) and by coupling with photoelectro-Fenton (PEC-PEF): this resulted in complete degradation of TPTCl in 15 min (kapp = 0.274 min-1) and total mineralization in 2 h. The mechanisms governing the photoelectrocatalytic processes are investigated in detail by means of electrochemical measurements and chemical probes, and a mineralization pathway for TPTCl is proposed.
关键词： photoelectro-Fenton,photoelectrocatalysis,fluorine-doped tin oxide,organotin pollutants,Dark PEC
更新于2025-09-23 15:21:01
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Validation of Hertzian Electromagnetism in a Rectangular Waveguide with Rotating PEC Termination
摘要： We provide a general formulation of electromagnetic scattering by a Perfect Electrical Conductor (PEC) object in arbitrary motion in the context of Hertzian Electrodynamics, which is followed by an application to the canonical problem of scattering of dominant TE mode incidence in presence of a PEC termination in accelerated rotational motion. Analytical solutions, which apply for arbitrary variations of angular velocity, are derived and supported with measurement results.
关键词： rectangular waveguide,PEC termination,TE mode,electromagnetic scattering,Hertzian Electrodynamics
更新于2025-09-23 15:19:57
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Carbon quantum dots modified anatase/rutile TiO2 photoanode with dramatically enhanced photoelectrochemical performance
摘要： Titanium dioxide (TiO2) is a promising photoanode material for photoelectrochemical (PEC) water splitting, but the severe bulk recombination of photongenerated carriers, the sluggish oxygen evolution reaction (OER) kinetics and the poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on the rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and light harvesting were obtained. The bulk charge separation efficiency (ηbulk) and the surface charge injection efficiency (ηsurface) of CQDs/A/R-TiO2 are 1.69 and 5.74 times higher than that of the pristine TiO2 at 0.6 V vs. RHE, respectively. The photocurrent of CQDs/A/R-TiO2 is increased by 11.72 times and the onset potential of CQDs/A/R-TiO2 is negatively shifted by 240 mV.
关键词： Anatase/rutile TiO2 heterojunction,Carbon quantum dots,Bulk and surface charge transfer kinetics,PEC,Light harvesting
更新于2025-09-23 15:19:57
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Annealing Induced Oxygen Defects on Green Sonochemically Synthesized ZnO Nanoparticles for Photoelectrochemical Water Splitting
摘要： Zinc oxide (ZnO) nanoparticles were prepared by a green process using a simple sonochemical method. The prepared nanoparticles were annealed at different annealing temperatures in order to determine the role of the annealing temperature on the structural, morphological and optical properties of the prepared material. The defects related photoluminescence properties of the ZnO nanoparticles are discussed in detail. X-ray photoelectron spectroscopy provided the information regarding the presence of the defects in the material. ZnO emission related to defect emission was observed to increase with annealing temperature upto 600°C and then decreased. These defects played a crucial role in the performance of the photo-electrochemical (PEC) activity. The PEC performance has increased with an increase in the amount of oxygen related defects present in the material due to annealing.
关键词： PEC water splitting,Defects,XPS,Green chemistry,ZnO
更新于2025-09-19 17:15:36
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New Understanding of Crystal Control and Facet Selectivity of Titanium Dioxide Ruling Photocatalytic Performance
摘要： Engineering crystals of titanium dioxide (TiO2) to expose with the most reactive facet has been proved to significantly improve the photocatalytic performance. While most of TiO2 with facets reported in the past were in a particle form, herein we directly grow TiO2 with arbitrarily tunable facets onto the transparent conductive substrate. This could reduce interparticle boundaries, and thus suppress charge recombination and facilitate more efficient charge transport compared to particle-assembled films. Combined systematic experimental and theoretical (Density Function Theory, DFT) studies reveal that fluoride ions (F-) and protons (H+) could play a synergistic role in controlling TiO2 crystals in the way that F- ions change the crystal phase of TiO2 to anatase with low-indexed facets, while H+ ions increase of {001}/{101} ratio. Moreover, the reductive and oxidative sites of facets are clearly elucidated by a selective photodeposition of noble metal and metal oxide. Different photocatalytic tests manifested that {001} facet, which is conventionally believed as the highest reactive facet, does not always show highest performance. On the other hand, the facets reactivity appeared to depend on the types of reactions (reduction or oxidation) and the co-existing synergy of facets. These findings would clarify the ambiguous understanding about the true factors controlling facets, the true order of reactivity of each facet that has still been controversial, and pave a way to improve both efficiency and selectivity of TiO2 in a wide variety of photocatalytic applications in the future.
关键词： Facet Control,CO2 Photoreduction,TiO2,Crystal Growth,PEC Water Splitting
更新于2025-09-19 17:15:36
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Facile designing and assessment of photovoltaic performance of hydrothermally grown kesterite Cu2ZnSnS4 thin films: Influence of deposition time
摘要： Herein, low cost precursor source Cu2ZnSnS4 (CZTS) nanocrystalline thin films at various reaction time were successfully synthesized via one step hydrothermal route. Hydrothermal route was employed to achieve control over the size and grain growth of CZTS films. As deposited CZTS films were analyzed for its optoelectronic, structural, morphological and electrochemical properties to investigate the effect of hydrothermal reaction time on growth and photovoltaic performance. The hydrothermal synthesis promoted to high absorption (104 cm?1) of the CZTS film with a decrease in optical band gap energy from 1.52 eV to 1.41 eV. Structural study revealed that, improved crystallinity with A1 mode of vibration for pure phase kesterite CZTS structure. Morphological transition was observed from nanograins to well grown and compact nanospheres. Compositional analysis illustrates, stoichiometric CZTS film formation with the desired valence state of Cu+, Zn2+, Sn4+ and S2? elements. Current density-voltage (J-V) measurement of FTO/CZTS/(0.3 M Eu3+/Eu2+)/Graphite cell configuration shows, highest photocurrent of 2.60 mA/cm2 and open circuit voltage of 754 mV was observed for CZTS4 sample with best photoconversion efficiency (η) 3.21% under illumination of 30 mW/cm2 light intensity. Electron impedance spectroscopy (EIS) showed that, generation of lower charge transfer resistance (Rct) with increase in reaction time.
关键词： Photoelectrochemical (PEC) cell,Cu2ZnSnS4 thin films,Electron impedance spectroscopy,Hydrothermal route
更新于2025-09-19 17:13:59
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ANALYSIS OF A NON-INTEGER DIMENSIONAL TUNNEL AND PERFECT ELECTRIC CONDUCTOR WAVEGUIDE
摘要： Solutions to the Maxwell equations for a planar non-integer dimensional perfect electric conductor (NID-PEC) waveguide are obtained. The space within the guide is NID in direction normal to walls of the waveguide. Field behavior within the waveguide is noted for di?erent values of the parameter, D, describing dimension of the NID space. For D = 2, classical results are recorded. The discussion is further extended by treating propagation in a tunnel within unbounded dielectric medium. The space within tunnel is also NID in direction perpendicular to walls of the tunnel. For di?erent values of D ?eld behaviors are also presented. It has been noted that for D = 2 and taking very high values of permittivity ((cid:2) → ∞) classical results for PEC waveguide are recorded, whereas for (cid:2) → ∞, ?eld behavior within tunnel matches with NID-PEC waveguide.
关键词： TE/TM modes,Maxwell equations,PEC waveguide,Non-integer dimensional space,fractal medium
更新于2025-09-19 17:13:59
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Recent Progress and Development in Inorganic Halide Perovskite Quantum Dots for Photoelectrochemical Applications
摘要： Inorganic halide perovskite quantum dots (IHPQDs) have recently emerged as a new class of optoelectronic nanomaterials that can outperform the existing hybrid organometallic halide perovskite (OHP), II–VI and III–V groups semiconductor nanocrystals, mainly due to their relatively high stability, excellent photophysical properties, and promising applications in wide-ranging and diverse fields. In particular, IHPQDs have attracted much recent attention in the field of photoelectrochemistry, with the potential to harness their superb optical and charge transport properties as well as spectacular characteristics of quantum confinement effect for opening up new opportunities in next-generation photoelectrochemical (PEC) systems. Over the past few years, numerous efforts have been made to design and prepare IHPQD-based materials for a wide range of applications in photoelectrochemistry, ranging from photocatalytic degradation, photocatalytic CO2 reduction and PEC sensing, to photovoltaic devices. In this review, the recent advances in the development of IHPQD-based materials are summarized from the standpoint of photoelectrochemistry. The prospects and further developments of IHPQDs in this exciting field are also discussed.
关键词： photovoltaic devices,PEC sensing,inorganic halide perovskite quantum dots,photocatalysis,photoelectrochemical applications
更新于2025-09-19 17:13:59
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Enhanced photoelectrochemical performance of NaNbO3 nanofibers photoanode coupled with visible-light active g-C3N4 nanosheets for water splitting
摘要： Sodium niobate nanofibers (NaNbO3-NF) have been synthesized by hydrothermal technique and further coupled with visible light responsive graphitic carbon nitride (g-C3N4) nanosheets in the different concentration ratio of 2:1 (2-CN), 4:1 (4-CN) and 8:1 (8-CN). A significant improvement in the photoelectrochemical (PEC) performance of g-C3N4/NaNbO3-NF (4-CN) nanostructured photoanode as compared to bare NaNbO3 photoanode is observed. A current density of 12.55 mA cm?2 at 1 V with respect to Ag/AgCl reference electrode is achieved for g-C3N4/NaNbO3-NF (4-CN) photoanode which is ~3 times higher than the NaNbO3-NF photoanode. Also, as compared to NaNbO3-NF, g-C3N4/NaNbO3-NF (4-CN) nanocomposite photoanode showed ~3 times improvement in the incident photon-to-current conversion efficiency. The improvement in the PEC performance of visible light active g-C3N4/NaNbO3-NF (4-CN) nanocomposite is attributed to the improved photoresponse of NaNbO3-NF due to the coupling of g-C3N4 and formation of type-II heterojunction between them leading to the enhanced separation of the photogenerated charge carriers. A possible reaction mechanism for the improved photoelectrochemical water splitting performance has been proposed for g-C3N4/NaNbO3-NF (4-CN) photoanode.
关键词： Photoelectrode,Nanocomposite,Heterojunction,g-C3N4/NaNbO3-NF,PEC Water Splitting
更新于2025-09-12 10:27:22