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Microwave-assisted oleothermal synthesis of graphene-TiO2 quantum dots for photoelectrochemical oxygen evolution reaction
摘要： In this work, it was reported the production of graphene-TiO2-quantum dots based on an oleothermal redox reaction. Using concepts of nanoemulsification, an oil-water stable nanodroplets were formed. This emulsion was treated at different temperatures in an oil-based medium. This is an advantage to obtain well dispersed hydrophilic nanoparticles, considering that using water as solvent promotes their agglomeration. The cluster of hydrate titanium is formed inside the water dispersed graphene oxide nanodroplet in the oil medium. This aspect assures a close connection between graphene layers and titanium ions, originating dispersed quantum dots of minimum size. Temperature and time of oleothermal reaction influence the degree of functionalization of the graphene layers and thus the photoluminescence characteristics. For the water splitting characterization, a transparent thin film was obtained using the electrophoresis. It was possible to correlate the degree of oxygen functionalization of the graphene layers with the oleothermal conditions and the generated photocurrents.
关键词： Oleothermal,Quantum dots,Photoluminescence,Graphene,Photocurrent
更新于2025-11-21 11:18:25
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Reinforced photoelectrochemical properties of nanostructural TiO2/C/SiO2 integrated on conductive Ti3SiC2
摘要： Herein, we constructed an ordered nanoporous embedding nanoparticles composite by anodic oxidation of Ti3SiC2 in fluorine containing organic electrolyte. Compared to anodized Ti which resulted in TiO2 nanotubes, the anodized Ti3SiC2 (ATSC) led to the formation of nanostructured TiO2/C/SiO2 composite. The morphologies of oxides in the composite also varied with different anodization parameters. The ATSC could be directly used as an electrode without further processes, which possessed a superior structure and composition with a visible-light photocurrent density of 7.56 μA cm?2, initial reversible area capacity of 6.18 F cm?2, which were respectively 1.32 and 6.87 times higher than those of the anodized Ti (AT), respectively. The ATSC synthesized by such a feasible fabricating strategy shows favorable photoelectrochemical properties and remarkable stability, and may broaden the bifunctional material prospects of anodized MAX phases.
关键词： Nanostructure,Photocurrent,Capacitance,Anodized Ti3SiC2,Photoelectrochemical
更新于2025-11-14 17:04:02
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Influence of Electrochemical Hydrogenation on the Circular Photocurrent in the Ag/Pd Nanocomposite
摘要： This work reports on a circular photocurrent in Ag/Pd nanocomposite films. The films, containing metal (Ag-Pd) and semiconductor (PdO) nanocrystallites in amorphous lead-silicate glass, are modified by electrochemical hydrogenation in a sulfuric acid solution. The photocurrent in the modified nanocomposite films is excited by nanosecond laser pulses at wavelengths of 532, 1064, and 1550 nm. In order to determine the circular and linear contributions in a transverse photocurrent, the dependences of the photocurrent on the degree of circular polarization of the exciting radiation are investigated. It is found that the electrochemical hydrogenation modification leads to a significant decrease of the electrical resistance and the polarization-sensitive transverse photocurrent in the films. It is also found that electrochemical hydrogenation significantly affects the ratio of the circular and the linear photocurrent components. The photocurrent is found to be generated on the subsurface layer of the films in the absence of crystalline phase component PdO.
关键词： circular photocurrent,Ag/Pd nanocomposite,electrochemical hydrogenation
更新于2025-11-14 15:13:28
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Infrared Light Management Using a Nanocrystalline Silicon Oxide Interlayer in Monolithic Perovskite/Silicon Heterojunction Tandem Solar Cells with Efficiency above 25%
摘要： Perovskite/silicon tandem solar cells are attractive for their potential for boosting cell efficiency beyond the crystalline silicon (Si) single-junction limit. However, the relatively large optical refractive index of Si, in comparison to that of transparent conducting oxides and perovskite absorber layers, results in significant reflection losses at the internal junction between the cells in monolithic (two-terminal) devices. Therefore, light management is crucial to improve photocurrent absorption in the Si bottom cell. Here it is shown that the infrared reflection losses in tandem cells processed on a flat silicon substrate can be significantly reduced by using an optical interlayer consisting of nanocrystalline silicon oxide. It is demonstrated that 110 nm thick interlayers with a refractive index of 2.6 (at 800 nm) result in 1.4 mA cm?2 current gain in the silicon bottom cell. Under AM1.5G irradiation, the champion 1 cm2 perovskite/silicon monolithic tandem cell exhibits a top cell + bottom cell total current density of 38.7 mA cm?2 and a certified stabilized power conversion efficiency of 25.2%.
关键词： monolithic perovskite/silicon tandem solar cells,infrared photocurrent absorption,nanocrystalline silicon oxide interlayers
更新于2025-10-22 19:40:53
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One-Step Electrodeposition of CuZnSn Metal Alloy Precursor Film Followed by the Synthesis of Cu2ZnSnS4 and Cu2ZnSnSe4 Light Absorber Films and Heterojunction Devices
摘要： CuZnSn metallic alloy precursor films were electrodeposited on Mo substrate from a Zn-rich bath solution yielding low deposition rates. The precursor films were converted to photovoltaic absorber films of Cu2ZnSnS4 and Cu2ZnSnSe4 by sulfurization and selenization processes. X-ray diffraction, Raman spectroscopy and photocurrent spectroscopy techniques were utilized for the identification of films. The surface morphology, uniformity and compactness of the films were examined by scanning electron microscopy. The precursor and absorber films had a uniform and compact structure. The precursor films were composed from the Cu3Sn, Cu6Sn5 and Cu5Zn8 phases and their grain size varied tightly with the cathode potential. The conversion of precursor films to Cu2ZnSnS4 and Cu2ZnSnSe4 were verified from the results of their X-ray diffraction, Raman shifts, and optical transition energies. To assess the device quality of the absorber films, CdS/Cu2ZnSnS4 and CdS/Cu2ZnSnSe4 heterojunction diodes were fabricated and their device parameters were determined. The diodes showed relatively good ideality factor of 1.3-1.9, current rectification factor of ~120, and reverse biased saturation current of ~30-60 μA/cm2. Photocurrent spectroscopy was utilized to evaluate the band gap energy and other optical transition energies of the absorber films from the short-circuit photocurrent of the diodes.
关键词： electrodeposition,CZTS,CZTSe,photocurrent,Raman
更新于2025-09-23 15:23:52
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A pyrophosphatase biosensor with photocurrent analysis
摘要： A light-induced photochemical biosensor was developed for the analysis of inorganic pyrophosphatase (PPase). PPase hydrolyzes pyrophosphate (PPi) into two independent o-phosphate ions. Two PPi units can chelate a copper ion (Cu2+), forming a PPi–Cu2+–PPi complex and preventing the Cu2+ triggers other reactions. A transparent indium tin oxide (ITO) electrode was coated with a layer of CdS quantum dots (QDs), and then 3,4-diaminobenzoic acid (DBA) was deposited as the anchor. A solution of the PPi–Cu2+–PPi complex and o-phenylenediamine (OPD) was mixed with the analytical sample and then a drop of the mixture was placed on the modified ITO electrode. In the absence of PPase, no reaction occurred between OPD and DBA. A photocurrent was obtained upon excitation of the CdS QDs under light. In the presence of PPase, Cu2+ was released from the complex, triggering the reaction of OPD with DBA on the electrode surface, thereby shielding the CdS QDs from excitation by the light. The observed photocurrent decreased. The difference in the two measured photocurrents corresponded to the activity of PPase. This photochemical biosensor had excellent sensitivity for PPase in the range from 0.8 to 5000 mU, with a limit of detection of 0.41 mU.
关键词： Quantum dots,Biosensor,o-Phenylenediamine,Photocurrent,PPase
更新于2025-09-23 15:23:52
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Facile synthesis of two-dimensional tailored graphitic carbon nitride with enhanced photoelectrochemical properties through a three-step polycondensation method for photocatalysis and photoelectrochemical immunosensor
摘要： Graphitic carbon nitride (g-C3N4) is an ideal alternative two-dimensional (2D) nanostructure for photocatalysis and photoelectrochemical (PEC) application, while controllably fabricating 2D shaped g-C3N4 nanolayers/nanosheets is still facing challenges. On the basis of temperature-dependent polymorphic characters, herein, a 2D extending g-C3N4 (g-CNS3) is synthesized from dicyandiamide as the precursor by operating the condensation temperature in a continuously three-step thermal polycondensation procedure. The g-CNS3 with film-like morphology showed improved visible-light absorption ability and enhanced PEC performance compared to g-CNS1 synthesized via the traditional one-step thermal polymerization method. Benefiting from its excellent PEC properties, the g-CNS3 exhibited high photocatalytic activity to removal MB with fast kinetics and served as the photoactive layer to construct a PEC immunosensor with high sensitivity and specificity for subgroup J avian leukosis virus detection. A linear range from 102.14 to 103.35 TCID50/mL and a detection limit of 102.08 TCID50/mL were obtained for the PEC immunoassay of the target virus. This work might provide a novel protocol for tailoring shaped 2D g-C3N4 nanosemiconductor with superior properties and shed light on its promising PEC applications.
关键词： Two-dimensional material,Photocurrent response,Graphitic carbon nitride,Photocatalysis,Photoelectrochemical immunosensor
更新于2025-09-23 15:23:52
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2D-Porphrinic Covalent Organic Framework-Based Aptasensor with Enhanced Photoelectrochemical Response for the Detection of C-Reactive Protein
摘要： In this study, a novel photoelectrochemical (PEC) aptasensor based on two-dimensional (2D) porphyrinic covalent organic frameworks (p-COFs) for the label-free detection of C-reactive protein (CRP) is presented. The obtained p-COFs possess high conductivity and an improved stability due to strong and rigid covalent linkages. The introduction of p-COFs hinder the recombination of electrons and holes, decreasing their band gap (Eg), thereby which improved the photocurrent conversion efficiency. Compared with pure porphyrin, p-COFs exhibited enhanced photocurrent intensity. An amplified photocurrent conversion efficiency and enhanced photocurrent results from H2O2, which act as active molecules and electron donors. As an unprecedented application of COFs in PEC bioanalysis, the detection of CRP with a PEC aptasensor is presented. The assembly of a CRP aptamer on the surface of Ag nanoparticles hinders the electron transfer, resulting in the decrease of the photocurrent response. This PEC aptasensor exhibits good analytical performances such as a rapid response, high stability, wide linear range and excellent selectivity, making COFs promising candidates for PEC bioanalysis.
关键词： C-reactive protein,Porphyrinic covalent organic framework,High photocurrent conversion efficiency,Photoelectrochemical aptasensor,Enhanced photocurrent
更新于2025-09-23 15:22:29
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Long-Range Activationless Photostimulated Charge Transport in Symmetric Molecular Junctions
摘要： Molecular electronic junctions consisting of nitroazobenzene oligomers covalently bonded to a conducting carbon surface using an established 'all-carbon' device design were illuminated with UV?vis light through a partially transparent top electrode. Monitoring junction conductance with a DC bias imposed permitted observation of photocurrents while varying the incident wavelength, intensity, molecular layer thickness, and temperature. The photocurrent spectrum tracked the in situ absorption spectrum of nitroazobenzene, increased linearly with light intensity, and depended exponentially on applied bias. The electronic characteristics of the photocurrent differed dramatically from those of the same device in the dark, with orders of magnitude higher conductance and very weak attenuation with molecular layer thickness (β = 0.14 nm?1 for thickness above 5 nm). The temperature dependence of the photocurrent was opposite that of the dark current, with a 35% decrease in conductance between 80 and 450 K, while the dark current increased by a factor of 4.5 over the same range. The photocurrent was similar to the dark current for thin molecular layers but greatly exceeded the dark current for low bias and thick molecular layers. We conclude that the light and dark mechanisms are additive, with photoexcited carriers transported without thermal activation for a thickness range of 5?10 nm. The inverse temperature dependence is likely due to scattering or recombination events, both of which increase with temperature and in turn decrease the photocurrent. Photostimulated resonant transport potentially widens the breadth of conceivable molecular electronic devices and may have immediate value for wavelength-specific photodetection.
关键词： charge transport,optoelectronics,photocurrent,molecular electronics,molecular orbital energy,tunneling barrier,HOMO?LUMO gap,photoinduced transport
更新于2025-09-23 15:22:29
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Construction of Ag@AgCl decorated TiO2 nanorod array film with optimized photoelectrochemical and photocatalytic performance
摘要： A novel Ag@AgCl/TNR film photocatalyst was successfully obtained by a facile multistep route. Using a well-organized TiO2 nanorod array (TNR) film as the starting material, Ag nanoparticles were uniformly deposited on the TNR film via a photochemical reduction, and in situ oxidation of Ag by FeCl3 solution resulted in the formation of Ag@AgCl/TNR film. The structure, morphology, composition, optical, photocatalytic and photoelectrochemical properties of the obtained films were investigated in detail. The results showed that core-shell Ag@AgCl can effectively promote the transfer of photo-generated electron-hole pairs, suppress their recombination, and enhance the visible light absorption. The Ag@AgCl/TNR film with 60 min oxidation time (S60) showed the highest photocurrent and best transfer performance of interfacial electrons in the electrochemical impedance spectroscopy (EIS) Nyquist plots. For the photodegradation of methyl orange (MO), the S60 exhibited the highest photocatalytic efficiency (90.8%) and good stability under visible light irradiation, which can be comparable and even better than the previous reports. A detailed photocatalytic mechanism was proposed on the basis of the fact that Ag nanoparticles with surface plasma resonance (SPR) can be excited by visible light and this unique structure effectively transfers photo-generated electrons from Ag to TiO2 conduction band, accomplished by the transfer of compensative electrons from a donor (Cl-) to Ag nanoparticles.
关键词： Nanorod array,Photocatalytic activity,Photocurrent,TiO2,Ag@AgCl
更新于2025-09-23 15:22:29