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Multiple structure formation and molecule dynamics in transient plasmas generated by laser ablation of graphite
摘要： Transient plasmas generated by ns - laser ablation of graphite in air have been investigated by complementary optical diagnosis techniques to study complex multiple structures generated in carbon laser produced plasmas (C-LPP) during the expansion phase. The overall emission was investigated by ICCD fast camera imaging and revealed the structuring of C-LPP into four distinct structures with di?erent evolutions. The dynamic of the C-LPP was analyzed on various expansion directions in order to understand the formation of the main CN dominant structure and of lateral “?aps” with dominant C2 emission. The kinetic and thermal energies of the resulted atoms, ions and molecules were investigated by means of space-and time-resolved optical emission spectroscopy and using the Boltzmann plot and Stark broadening approaches. The e?ect of the background gas pressure on the formation of molecular carbon structures is discussed and an optimum range of working pressure which maximizes the generation of C2 is found. Based on the acquired data a scenario for the complex carbon structures generation in C-PLL as function of the background gas is proposed.
关键词： Complex carbon structures,ns-laser produced plasma,molecule dynamics,Graphite,Multiple plasma structuring,ICCD fast camera imaging
更新于2025-09-16 10:30:52
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Impulse Laser Effect on Graphitized Surface of Y–TZP-Ceramics
摘要： The role of a graphite layer on the surface of ceramics based on tetragonal zirconia, partially stabilized by yttrium oxide (Y–TZP-ceramics) under the action of a pulsed laser was studied using original methodology. It has been found that surface graphitization increases the fraction of absorbed laser radiation, and as a result, heating, melting and evaporation of Y–TZP-ceramics occur under less intense modes, favorably affecting the use of pulsed laser radiation for surface modification.
关键词： Y–TZP-ceramics,graphite layer,pulsed laser effect,surface layer,roughness,surface morphology
更新于2025-09-12 10:27:22
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Lithium Distribution in Structured Graphite Anodes Investigated by Laser-Induced Breakdown Spectroscopy
摘要： For the development of thick film graphite electrodes, a 3D battery concept is applied, which significantly improves lithium-ion diffusion kinetics, high-rate capability, and cell lifetime and reduces mechanical tensions. Our current research indicates that 3D architectures of anode materials can prevent cells from capacity fading at high C-rates and improve cell lifespan. For the further research and development of 3D battery concepts, it is important to scientifically understand the influence of laser-generated 3D anode architectures on lithium distribution during charging and discharging at elevated C-rates. Laser-induced breakdown spectroscopy (LIBS) is applied post-mortem for quantitatively studying the lithium concentration profiles within the entire structured and unstructured graphite electrodes. Space-resolved LIBS measurements revealed that less lithium-ion content could be detected in structured electrodes at delithiated state in comparison to unstructured electrodes. This result indicates that 3D architectures established on anode electrodes can accelerate the lithium-ion extraction process and reduce the formation of inactive materials during electrochemical cycling. Furthermore, LIBS measurements showed that at high C-rates, lithium-ion concentration is increased along the contour of laser-generated structures indicating enhanced lithium-ion diffusion kinetics for 3D anode materials. This result is correlated with significantly increased capacity retention. Moreover, the lithium-ion distribution profiles provide meaningful information about optimizing the electrode architecture with respect to film thickness, pitch distance, and battery usage scenario.
关键词： laser-induced breakdown spectroscopy,3D battery,lithium-ion battery,ultrafast laser ablation,graphite anode
更新于2025-09-12 10:27:22
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All-Fiber Erbium-doped Q-Switched Laser with Recycled Graphite Oxide
摘要： This work demonstrates a passively Q-Switched fiber laser employing graphite oxide as a saturable absorber, generating tunable microsecond pulses with kHz repetition rates, pulse energies of up to 15.54 nJ and the pulse-to-pulse timing jitter of 46.14 fs. The graphite oxide samples were obtained by recycling the graphite present in Li-ion batteries utilized in cell phone devices through a chemical separation and subsequent oxidation process. Sample characterization employing X-ray diffraction, solid-state nuclear magnetic resonance and Raman spectroscopy showed that the produced graphite oxide exhibited a homogeneously oxidized structure. These results indicate that applications in the physics of pulsed lasers can benefit from the recycling of lithium batteries, directing the process of discarding spent batteries.
关键词： Recycled Graphite Oxide,Lithium Batteries,Erbium-Doped Fiber Laser,Saturable Absorber,Q-Switched
更新于2025-09-12 10:27:22
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WN/nitrogen-doped reduced graphite oxide hybrids for triiodide reduction in dye-sensitized solar cells
摘要： The development of low-cost, environmental friendliness, outstanding catalytic activity, superior conductivity and good stability counter electrode (CE) catalyst in dye-sensitized solar cells (DSSCs) is important to promote the commercial application of DSSCs. Here, WN/nitrogen-doped reduced graphite oxide hybrids (WN/NrGO) had been synthesized by hydrothermal method followed by nitridation treatment, which used as CE catalysts for catalyzing I3? to I?. The combined WN and nitrogen-doped reduced graphite oxide (NrGO) into WN/NrGO could effectively regulate the catalytic activity for the reduction of I3?, accelerate the charge transfer at the interface, and then the synergistic effect between of them can be fully achieved. When the WN/NrGO served as the CE catalyst in DSSCs, the photoelectric conversion efficiency (PCE) of 7.42% has been obtained, compared to the conventional Pt-based DSSCs (7.71%). Meanwhile, as-prepared WN/NrGO exhibited higher PCE than that of the solo WN (6.19%) and NrGO (5.81%) in parallel. A series of electrochemical measures revealed that the WN/NrGO displayed the higher catalytic activity and charge transfer ability than that of the solo WN and NrGO, so the synthesized low-cost WN/NrGO have an potential to be used as the effectively CE catalysts for the replacement of the noble Pt.
关键词： Dye-sensitized solar cells,Triiodide reduction,Counter electrode,WN/nitrogen-doped reduced graphite oxide
更新于2025-09-12 10:27:22
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Charge transfer improvement of ZnO-based dye-sensitized solar cells modified with graphite nanosheets and bilayer photoelectrode structures
摘要： In this work, dye-sensitized solar cells (DSSCs) were fabricated with different photoelectrode structures consisting of a ZnO-based photoelectrode, a ZnO/Au Schottky barrier-based photoelectrode, graphite nanosheets loaded on a ZnO (GZnO)-based photoelectrode, graphite nanosheets loaded on a ZnO nanoparticles (GZnO NPs)-based photoelectrode and graphite nanosheets loaded on a ZnO nanoparticles/ZnO (GZnO NPs/ZnO) as a bilayer-based photoelectrode. The photovoltaic characteristics of DSSCs were investigated based on: the power conversion efficiency (PCE), short-circuit current density (Jsc), open-circuit voltage and fill factor. The kinetics electron transport of impedance spectros- DSSCs was carried out using electrochemical copy (EIS). The semi-circle in the Nyquist plot was calculated to rep- resent the charge transfer resistance (Rct). It was found that the GZnO NPs/ZnO bilayer-based photoelectrode exhibited the max- imum Jsc (9.185 mA/cm2) and maximum PCE (2.37%), which resulted by the minimum Rct in the device. The result can be interpreted as showing that a graphite nanosheet structure improves the electron transport property which produces an excellent charge transfer mechanism in the photoelectrode. Accordingly, enhanced perform- ance of ZnO-based dye-sensitized solar cells with graphite nano- sheets loaded on a ZnO nanoparticles layer could be simply explained in terms of the charge transfer mechanism.
关键词： graphite nanosheets,ZnO,dye-sensitized solar cells,charge transport
更新于2025-09-12 10:27:22
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Enhanced Physical and Thermal Performance of Expanded Graphite-Based Heat Sink for LED Radiator
摘要： An experimental study was carried out to investigate the heat transfer characteristics of Cu and Al–modified expanded graphite heat sinks. In this study, the heat sinks were composed of expanded graphite as an active material, Cu and Al as heat transfer enhancement material and resin as a binder. Graphite with high purity was obtained via treated with different amount of Na2CO3. The as-prepared heat sinks were characterized by XRD, pH, SEM, electrical resistivity, bending strength and thermal analysis. The metal Al modified expanded graphite composite heat sink in our experiment exhibited a good rate of capability in physical and thermal performances. Sample GA5-300 showed highest thermal diffusivity and thermal conductivity.
关键词： Expanded graphite,Heat transfer,Thermal diffusivity and conductivity
更新于2025-09-12 10:27:22
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High performance graphene-like thinly layered graphite based visible light photodetector
摘要： In this work, the drop casting method is utilized to obtain a thin graphene-like graphite layer as a photodetection layer on a SiO2/Si substrate, and its performance is characterized to determine its potential use in commercial applications. The thin layer is formed by first synthesizing graphite soot from a butane flame before being turned into a liquid solution and drop-casted onto the substrate to form a thin graphene-like graphite film. Field emission scanning electron microscope and Raman vibrational mode analyses indicate that the fabricated graphene-like graphite layer has characteristics similar to the graphene. The graphene-like graphite photodetector demonstrates a narrow photoresponse from 530 to 680 nm, covering visible sources from green to red. The responsivity and external quantum efficiency of the device under the illumination of red laser 660 nm is found to be around 148 mA W?1 and 27.8% respectively and is faster than that reported for similar systems using graphene and reduced graphene oxide previously. A fast response time of 83.7 and 28 μs at a modulation frequency of 1.0 and 10000 Hz respectively from the graphene-like thinly layered graphite photodetector shows potential application for the development of low-cost carbon-based photodetectors in near future.
关键词： Responsivity,Butane flame,Graphite,Frequency modulation,Photodetector
更新于2025-09-12 10:27:22
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Low-temperature preparation of crystallized graphite nanofibers for high performance perovskite solar cells
摘要： Integration of two-dimensional graphite nanosheets into one-dimensional graphite nano?bers is essential for deep application of graphite materials. Here, we report preparation of crystallized graphite nano?bers by nozzle-less electrospinning and subsequent low-temperature heat treatment (500 °C). Depending on this graphitized one-dimensional nanostructure, we ?rst apply the graphite nano?bers as sca?old for perovskite solar cells (PSCs), which would provide a charge transfer highway in the light absorb layer and then improve the performance of devices. A high power conversion e?ciency of 18.23% was recorded for the graphite nano?bers based PSC with high ?ll factor of 76%.
关键词： Perovskite solar cell,Charge transfer,Electrospinning,Graphite nano?bers,Graphitization temperature
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Attosecond Soft X-Ray Absorption Spectroscopy in Graphite
摘要： X-ray absorption fine-structure (XAFS) spectroscopy is a well-established technique capable to extract information on the electronic and lattice structure of a material with atomic resolution. Analysis of the XAFS spectrum in the near-edge region (XANES) provides information about the electronic configuration. Structural information is extracted from the extended XAFS (EXAFS) spectrum, consisting of several hundreds of eV above the absorption edge. Connecting the spectroscopic capabilities of XAFS technique to high temporal resolution would give the possibility to follow electronic and lattice dynamics in real time. Here, we present the simultaneously access to electronic and lattice parameters via XAFS spectroscopy using isolated attosecond soft X-ray (SXR) pulses covering the entire water window region (280 eV to 540 eV). We demonstrate the novel capabilities of attosecond XAFS (attoXAFS) by identifying the (cid:1)* and (cid:1)* orbital contributions to the density of states in highly oriented pyrolithic graphite (HOPG) simultaneously with the four characteristic bonding distances of graphite’s hexagonal lattice.
关键词： attosecond,graphite,soft X-ray,electronic and lattice dynamics,XAFS spectroscopy
更新于2025-09-11 14:15:04