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Simply synthesized nitrogen-doped graphene quantum dot (NGQD)-modified electrode for the ultrasensitive photoelectrochemical detection of dopamine
摘要： Recently, nitrogen-doped graphene quantum dots (NGQDs), as a new type of quantum semiconductor and photoelectrochemical material, are promising candidates in photoelectric sensing, water splitting, and biological imaging and have various potential application prospects. In this work, NGQDs were prepared by a simple calcination method, and then a photoelectrochemical sensing platform based on the NGQDs electrode with superior photoelectrochemical activity was designed and fabricated for the detection of dopamine (DA). Benefitting from the quantum effect and size effect, NGQDs displayed an enhanced photocurrent effective within ultra-low detection limit (0.03 μm), wide detection range (0.03–450 and 450–9680 μm), and high sensitivity in detecting DA with the assistance of ultraviolet light irradiation. The NGQDs electrode also showed continuous and stable photocurrent densities after long-term experiment, indicating the excellent durability of NGQDs for DA detection.
关键词： ultrasensitive detection,NGQDs,photoelectrochemistry,dopamine
更新于2025-09-11 14:15:04
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Surface protective and catalytic layer consisting of RuO2 and Pt for stable production of methylcyclohexane using solar energy
摘要： A particulate (ZnSe)0.85(CuIn0.7Ga0.3Se2)0.15 (ZnSe:CIGS)-based photocathode modified with RuO2 and Pt species exhibited improved photoelectrochemical (PEC) activities and stability for hydrogen evolution as well as production of methylcyclohexane, the promising hydrogen carrier, from toluene with using a highly alkaline aqueous solution as a hydrogen source under sunlight with almost 100% of Faradaic efficiency. It was revealed that the co-loading of RuO2 with Pt changed the Pt oxidation state, partly explaining the improved activity and stability, associated with an anchoring effect of Pt. It was also determined that such highly alkaline conditions promote selective MCH production, possibly due to improved performance of the anion exchange membrane. The present study involving the construction of a surface protective/catalytic layer suggests a novel approach to artificial photosynthesis for solar energy harvesting in the form of organic hydrides.
关键词： methylcyclohexane,hydrogen carrier,photoelectrochemistry,near infrared-responsive photocathode,RuO2 surface modification
更新于2025-09-10 09:29:36
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Gold/WS2 nanocomposites fabricated by in-situ ultrasonication and assembling for photoelectrochemical immunosensing of carcinoembryonic antigen
摘要： Tungsten disulfide (WS2) nanosheets were obtained by exfoliating WS2 bulk crystals in N-methylpyrrolidone by ultrasonication. Gold nanoparticles (GNPs) were synthesized by in-situ ultrasonication of sodium citrate and HAuCl4 while fabricating the WS2 nanosheets. In this way, the GNPs were self-assembled on WS2 nanosheets to form a GNPs/WS2 nanocomposite through interaction between sulfur and gold atoms. The photoelectrochemical response of WS2 nanosheets is significantly enhanced after integration of the GNPs. The GNPs/WS2 nanocomposite was coated onto a glassy carbon electrode (GCE) to construct a sensing interface which then was modified with an antibody against the carcinoembryonic antigen (CEA) to obtain a photoelectrochemical immunosensor for CEA. Under optimized conditions, the decline in relative photocurrent is linearly related to the logarithm of the CEA concentration in the range from 0.001 to 40 ng mL?1. The detection limit is 0.5 pg mL?1 (at S/N = 3). The assay is sensitive, selective, stable and reproducible. It was applied to the determination of CEA in clinical serum samples.
关键词： Gold nanoparticles,CEA,Photoelectrochemistry,Nanosheets,Transition metal dichalcogenides,Immunosensor
更新于2025-09-10 09:29:36
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Impact of the anodization time on the photocatalytic activity of TiO <sub/>2</sub> nanotubes
摘要： Titanium oxide nanotubes (TNTs) were anodically grown in ethylene glycol electrolyte. The influence of the anodization time on their physicochemical and photoelectrochemical properties was evaluated. Concomitant with the anodization time, the NT length, fluorine content, and capacitance of the space charge region increased, affecting the opto-electronic properties (bandgap, bathochromic shift, band-edge position) and surface hydrophilicity of TiO2 NTs. These properties are at the origin of the photocatalytic activity (PCA), as proved with the photooxidation of methylene blue.
关键词： nanotubes,photocatalytic activity,photoelectrochemistry,titanium(IV) oxide (TiO2),fluorine doping
更新于2025-09-10 09:29:36
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Facile fabrication and optimization of bowl-like ZnO/CdS nano-composite thin films with hierarchical nanopores and nano-cracks for high-performance photoelectrochemistry
摘要： A special nano-structured composite ZnO/CdS thin film with hierarchical nanopores and nano-cracks has been synthesized by a facile two-step method for the first time, in which both loadings of ZnO and CdS are optimized. We first fabricated the hierarchical nano-porous ZnO thin film through rapid gas/liquid interface assembly and layer-by-layer transfers of bowl-like ZnO nanoparticles for thirteen times. The ZnO nanobowls are prepared by a simple solution chemical reaction without using any templates. After annealing, the assembled ZnO film is sensitized with CdS nanoparticles by successive ionic layer adsorption and reactions for six cycles. Nano-cracks form for the ZnO/CdS nano-composite film by calcination, which is due to the different thermal expansion behavior between the ZnO film and the CdS layer. The facilely optimized ZnO/CdS films can serve as a promising photoanode in a photoelectrochemical cell, and it can generate a saturated photocurrent density as high as 7.8 mA cm?2 at ?0.9 V (vs. Hg|Hg2SO4|saturated K2SO4) under visible light illumination of 100 mW cm?2 in an aqueous solution of 0.5 M Na2S, corresponding to a solar-to-electricity conversion efficiency of 6.6%.
关键词： Nano-crack,CdS,Bowl-like ZnO nanoparticle,Gas/liquid interface assembly,Hierarchical nanopores,Photoelectrochemistry
更新于2025-09-10 09:29:36
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Biosynthetic Transition Metal Chalcogenide Semiconductor Nanoparticles: Progress in Synthesis, Property Control and Applications
摘要： Transition metal (TM) chalcogenides are a group of semiconductor materials with applications that range from antibacterial particles to thin films in energy conversion devices. Significant progress in synthetic biology combined with the benefits of low energy consumption and low toxic waste burden of “green synthesis,” have directed considerable research attention to the biosynthesis of these inorganic materials. TM chalcogenide nanoparticles (NP) can be produced by a variety of microorganisms including bacteria, fungi, algae, and yeast, as well as cell-free approaches using enzymes. Recent research shows that the size, crystal structure, and bandgap of these TM NPs can be well controlled, which has led to prototypical applications of these biosynthetic NPs in the areas of bio-remediation, bio-imaging, photocatalysis, and energy conversion. This review is the first to combine recent progress in the biosynthesis, property control, and applications of TM chalcogenide NPs.
关键词： photovoltaic,fluorescence,antibacterial,bioimaging,photoelectrochemistry,photocatalytic
更新于2025-09-09 09:28:46
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Exploring the photoelectrocatalytic behavior of free-standing TiO2 nanotube arrays on transparent conductive oxide electrodes: Irradiation direction vs. alignment direction
摘要： Although one-dimensional TiO2 nanotube arrays (TNA) grown on Ti substrates via electrochemical anodization are extensively studied in photoelectrochemistry, the photo(electro)catalytic activity of TNA detached from the Ti substrates remains unexplored. Herein, we synthesize TNA samples with various pore sizes (40?100 nm) and tube lengths (4?15 μm) via two-step electrochemical anodization, and transfer them to transparent conducting oxide (i.e. fluorine-doped tin oxide; FTO) substrates in normal (n) alignment (front plane outward) and reverse (r) alignment (backplane outward). The front and back planes of the as-fabricated TNA film are the same based on X-ray diffraction (anatase structure), X-ray photoelectron spectroscopy (Ti and O), and UV-vis transmittance data, though the tubes are open in the front and closed in the back. Regardless of the direction of irradiation (SE: FTO → TNA vs. EE: TNA → FTO), longer tubes generate a higher photocurrent (Iph) due to the large light absorption. However, for the same alignment of TNA (either n- or r-TNA), SE irradiation leads to a very large Iph (e.g., nSE > nEE), whereas n-TNA consistently generates a larger Iph than r-TNA for a given irradiation direction (i.e., n > r). The photocatalytic decomposition of phenol follows the same tendency (n > r); however, the Faraday efficiency (based on the photocharge) is higher with EE (nEE 28%, rEE 20%) than SE (rSE 11%, nSE 7%) irradiation. These photoelectrochemical and photocatalytic behaviors are explained in terms of charge carrier generation (FTO/TNA vs. TNA/solution), dissimilar charge carrier transfer pathways (e? transfer through tube framework vs. h+ transfer via radial direction), and charge injection at the tube (open vs. clogged tube mouth)/solution interface. The time-resolved photoluminescence (TRPL) emission and incident photon-to-current efficiency (IPCE) are also studied to gain insight into the charge transfer kinetics.
关键词： Photocatalysis,Anodization,Charge transfer,Photoelectrochemistry,Morphology
更新于2025-09-04 15:30:14
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Water reduction into hydrogen using Rh-doped SrTiO3 photoelectrodes surface-modified by minute amounts of Pt: Insights from heterogeneous kinetic analysis
摘要： In this paper, we report on the photoelectrochemical hydrogen evolution reaction (HER) from water using Rhodium-doped strontium titanate, surface-modified by the addition of minute amounts of platinum nanoparticles. Platinum has been used in an attempt to increase the charge transfer efficiency of the photoelectrode but also to investigate the balancing effect of surface co-catalysis on charge transfer versus recombination processes. The dynamics of the HER in pH-neutral aqueous solutions has been investigated by Photoelectrochemical Impedance Spectroscopy. Experimental impedance data has been analyzed using a model derived from considerations on heterogeneous kinetics. From the best experimental vs. calculation PEIS fits, microscopic rate parameters have been determined over an extended range of electrical potential. The charge transfer (kt ) and recombination (kr) rate constants have been found to vary exponentially with the applied potential. The analysis of the potential dependence of kt led to a Butler-Volmer transfer coefficient of 0.21. The analysis of the potential dependence of the recombination rate constant kr led to the determination of a non-ideality factor b ? 0.04 (b ? 1 for ideal interfaces), demonstrating the strong non-ideal behavior of the interface. Such non-ideal behavior has been attributed to the presence of a high density of surface states. The space charge capacitance under inversion conditions, i.e. when a strong reversed bias is applied and when the surface of this p- semiconductor exhibits a n-type conductivity, has also been measured and analyzed.
关键词： Water splitting,Kinetics,Photoelectrochemistry,Hydrogen
更新于2025-09-04 15:30:14
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High-activity Fe3O4 nanozyme as signal amplifier: a simple, low-cost but efficient strategy for ultrasensitive photoelectrochemical immunoassay
摘要： Sensitive but with simple, inexpensive detection of disease-related biomarkers in real biological samples is of quite necessity for early diagnosis and disease surveillance. We herein first introduced high-activity Fe3O4 nanozyme as signal amplifier to develop an ultrasensitive photoelectrochemical (PEC) immunoassay, which meanwhile has the distinct merits of both simplicity and low cost compared with previously reported enzyme-labeling PEC immunoassays. In the proposal, to illustrate and describe the PEC platform, prostate-specific antigen (PSA, Ag) was used as a target model. Specifically, ZnO nanorods (ZnO-NRs) grown vertically on a bare indium–tin oxide (ITO) electrode was deposited with ZnIn2S4 nanocrystals, producing ZnIn2S4/ZnO-NRs/ITO photoelectrode as the PEC matrix to modify capture PSA antibody (Ab1). Histidine-modified Fe3O4 (his-Fe3O4) nanozyme as signal amplifier was linked with signal PSA antibody (Ab2) to form his-Fe3O4@Ab2 conjugate, and was anchored through specific sandwich immunoreaction. The labeling his-Fe3O4 nanozyme acted as a peroxidase to induce the generation of the insoluble and insulating precipitation, resulting in an evident decrease in the photocurrent signal. On account of combined effects of high catalytic efficiency of the his-Fe3O4 nanozyme and excellent PEC properties of the ZnIn2S4/ZnO-NRs/ITO photoelectrode, ultralow detection limit of 18 fg/mL for target Ag detection was achieved. Besides, as high-activity his-Fe3O4 nanozyme has substituted natural enzyme as signal amplifier, simplicity and low cost of the PEC immunoassay was realized.
关键词： photoelectrochemistry,Fe3O4,immunoassay,nanozyme,signal amplifier
更新于2025-09-04 15:30:14
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Photo-Electrochemical Investigation of Inorganic/Organic Interfaces Assembly Consisting of Zn-Doped WO3 /Poly 4-(Thiophen-3-yl) Aniline
摘要： inorganic/Organic/Interfaces (IOI) consisting of Zn-doped WO3 (Zn-WO3) Photoactivities at /Poly 4-(Thiophen-3-yl) aniline (P3ThA) assemblies were investigated in nanoparticle suspensions and in thin solid film forms. The effects of P3ThA modifier on the photoelectrochemical behavior of the IOI were investigated using [Fe(CN)6]4- as a photoactive donor of hydrated electrons. Results show that the adsorption process of [Fe(CN)6]3- (photolysis product) controls the photoactivity outcomes of the IOI assemblies. P3ThA shows a greater heterogeneous photochemical response than native Zn-WO3. The band alignment between Zn-WO3 and P3ThA is of a p-p junction straddling gap type, where the charge transfer process is achieved through a hole transfer mechanism. The interface activities were explained by analyzing the IOI junction characteristics such as electron affinity, work function and hole/electron barrier heights. The creation of hybrid sub-band states close to the Fermi energy level at the interface was suggested. The aqueous nano-systems retained moderate stability as indicated by the reproducibility of their photocatalytic activities. Both [Fe(CN)6]4- and P3ThA contributed to the stability of the native Zn-WO3 surfaces.
关键词： photoelectrochemistry,solar energy,heterojunctions,semiconductors
更新于2025-09-04 15:30:14