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Pure CuBi <sub/>2</sub> O <sub/>4</sub> Photoelectrodes with Increased Stability by Rapid Thermal Processing of Bi <sub/>2</sub> O <sub/>3</sub> /CuO Grown by Pulsed Laser Deposition
摘要： A new method for enhancing the charge separation and photo-electrochemical stability of CuBi2O4 photoelectrodes by sequentially depositing Bi2O3 and CuO layers on fluorine-doped tin oxide substrates with pulsed laser deposition (PLD), followed by rapid thermal processing (RTP), resulting in phase-pure, highly crystalline films after 10 min at 650 °C, is reported. Conventional furnace annealing of similar films for 72 h at 500 °C do not result in phase-pure CuBi2O4. The combined PLD and RTP approach allow excellent control of the Bi:Cu stoichiometry and results in photoelectrodes with superior electronic properties compared to photoelectrodes fabricated through spray pyrolysis. The low photocurrents of the CuBi2O4 photocathodes fabricated through PLD/RTP in this study are primarily attributed to their low specific surface area, lack of CuO impurities, and limited, slow charge transport in the undoped films. Bare (without protection layers) CuBi2O4 photoelectrodes made with PLD/RTP shows a photocurrent decrease of only 26% after 5 h, which represents the highest stability reported to date for this material. The PLD/RTP fabrication approach offers new possibilities of fabricating complex metal oxides photoelectrodes with a high degree of crystallinity and good electronic properties at higher temperatures than the thermal stability of glass-based transparent conductive substrates would allow.
关键词： CuBi2O4,solar water splitting,rapid thermal processing,ternary oxides,pulsed laser deposition
更新于2025-09-23 15:19:57
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Efficacy of cellulose paper treated with Cu and Ag oxide nanoparticles synthesized via pulsed laser ablation in distilled water in the annihilation of bacteria from contaminated water
摘要： In the present work, nanoparticles of copper and silver synthesized via pulsed laser ablation of the respective targets in distilled water are applied to cellulose filter paper to check their effectiveness in the annihilation of bacteria from contaminated water. The treatment of the filter paper with the nanoparticles is found to be an excellent way to get rid of two common bacteria, Staphylococcus aureus and Escherichia coli, from contaminated water. The spread plate method on agar, employed to test the antibacterial efficacy of the nanoparticle-treated papers, clearly shows the absence of bacterial growth upon coming into contact with the nanoparticles in the filter paper. These results were further substantiated by the growth kinetic study of the bacteria that exhibited slow growth of the bacteria that were exposed to the nanoparticles. The morphology of the bacteria that came into contact with the nanoparticles is found to be adversely affected by the nanoparticles. Both copper and silver nanoparticles show a similar extent of antibacterial activity.
关键词： antibacterial,cellulose filter paper,pulsed laser ablation,nanoparticles,contaminated water
更新于2025-09-23 15:19:57
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Effect of the scanning speed on the microgroove formation regime in nanosecond-pulsed laser scanning ablation of cermet
摘要： As the field of biomedicine continues to grow, so will the need for the quick and efficient manufacture of high-quality micro-textures, such as microfluidic systems, for biomedical functions. The utilization of a nanosecond-pulsed laser enables the realization of an efficient ablation rate in the preparation of a microscaled texture for biomedicine applications. To obtain high-quality ablated features, it is necessary to understand the interaction regime between the pulse laser and cermet. In this work, the effects of the scanning speed on formation mechanisms of microgrooves in pulse laser scanning ablation of cermet are investigated. The relative ablation processes in terms of the particle ejection and the morphology of the ablation traces under various scanning speeds are characterized. In addition, pump-probe shadowgraph imaging is used to observe the ablation dynamics and laser-plume interaction. The results demonstrate that the plume shielding effect, which stems from the intensive pulse energy overlap in the irradiated region, tends to occur at a low scanning speed and results in an intermittent ablation regime. Moreover, there is a critical scanning speed for overcoming the plume shielding effect when other laser parameters are kept constant. To realize an even and continuous ablation process, a high scanning speed that exceeds this critical value should be applied.
关键词： Ablation regime,Pulsed laser scanning ablation,Micro-texture fabrication,Plume shielding effect
更新于2025-09-23 15:19:57
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Silicon nanoparticle generation and deposition on glass from waste silicon powder by nanosecond pulsed laser irradiation
摘要： Silicon nanoparticles can be used for fabricating electrodes in high-performance lithium ion batteries and other high value-added products. Currently, silicon nanoparticles are fabricated by pulsed laser irradiation of single-crystal silicon wafers in water. In this study, we proposed silicon nanoparticle generation by using a nanosecond pulsed laser to irradiate waste silicon powder which is disposed from wire-saw slicing processes of silicon ingots. The laser-induced nanoparticles were backward-transferred and deposited on a glass substrate. It was found that the morphology and amount of the deposited nanoparticles was strongly dependent on the distance between the glass substrate and the waste silicon powder target. Raman spectroscopy showed that the silicon nanoparticles were crystalline, and the average size was ~10 nm. The obtained silicon nanoparticles had high purity, as the diamond abrasives included in the waste silicon powder were removed through oxidation and vaporization during laser irradiation.
关键词： Raman spectroscopy,Silicon crystal,Waste silicon powder,Nanoparticle,Nanosecond pulsed laser
更新于2025-09-23 15:19:57
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Iron Oxide Nanopowders Obtained via Pulsed Laser Ablation, for Supercapacitors
摘要： Nano-sized magnetite powders with addition of iron nitrides were synthesized via pulsed laser ablation (PLA) of an iron target in atmospheric air. A series of iron oxide nanopowders with various phase compositions (ranging from magnetite to hematite) and structures (from 2D lamellas and spherical nanoparticles to continuous 3D structures) were prepared via heat treatment of the initial (as-synthesized) powder at temperatures in the range 200–500°C. The powders were introduced into the composition of carbon paste electrodes (CPEs). The capacitive characteristics of the electrodes prepared were studied in comparison to a commercial electroexplosive iron oxide powder. The capacitances of electrodes were matched to the structural characteristics of the materials and their phase compositions. With the chosen electrode-preparation method, the powder heat-treated at 500°С (sample Fe/500) showed the highest capacitance. The potential of the studied ultrafine materials based on ablative iron oxide was shown for use in electrodes for supercapacitors.
关键词： supercapacitor,specific capacitance,pulsed laser ablation,iron oxides,nanopowder
更新于2025-09-23 15:19:57
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Influence of the pulse duration at near-infrared wavelengths on the laser-induced material removal of hot-dipped galvanized steel
摘要： Hot-dipped galvanized steel is processed with short- and ultrashort-pulsed lasers in air at near-infrared wavelengths with pulse durations ranging from 350 fs to 241 ns. The morphology of the ablated craters (processed over a range of laser fluence levels and a number of laser pulses) is analyzed by confocal laser scanning microscopy and scanning electron microscopy. The ablation threshold of galvanized steel is found to increase with laser pulse durations following a simple power Fth ? A:τB law. Longer pulse durations in the nanosecond regime, as compared to pulse durations in the picosecond and femtosecond regime, result in higher ablation efficiency and energy penetration depth at the cost of surface quality.
关键词： ablation efficiency,ultrashort-pulsed laser,galvanized steel,ablation threshold,rim
更新于2025-09-23 15:19:57
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Defect mediated transport in self-powered, broadband and ultrafast photoresponse of MoS <sub/>2</sub> /AlN/Si based photodetector
摘要： By combining unique properties of ultrathin 2D materials with conventional 3D semiconductors, devices with enhanced functionalities can be realized. Here we report a self-powered and ultrafast photodetector based on hybrid MoS2/AlN/Si heterostructure. The heterojunction is formed by depositing MoS2 thin film by pulsed laser deposition on AlN/Si(111) template. The vertical transport properties of the device under dark and light illumination conditions, exhibit an excellent photoresponse in a broad range of wavelengths (300–1100 nm) at 0 V. The maximum responsivity of this photodetector is found to be 9.93 A/W at wavelength of 900 nm. The device shows an ultrafast temporal response with response/recovery times of 12.5/14.9 μs. X-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy reveal presence of native oxygen impurities in AlN, throughout the bulk of the film. These oxygen defects form a deep donor level in AlN and play a crucial role in the transport of the photogenerated carriers, resulting in enhanced device performance.
关键词： broadband and ultrafast photoresponse,deep defects,MoS2,AlN,pulsed laser deposition
更新于2025-09-23 15:19:57
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Pulsed Laser Deposition of Bismuth Vanadate Thin Filmsa??The Effect of Oxygen Pressure on the Morphology, Composition, and Photoelectrochemical Performance
摘要： Thin layers of bismuth vanadate were deposited using the pulsed laser deposition technique on commercially available FTO (fluorine-doped tin oxide) substrates. Films were sputtered from a sintered, monoclinic BiVO4 pellet, acting as the target, under various oxygen pressures (from 0.1 to 2 mbar), while the laser beam was perpendicular to the target surface and parallel to the FTO substrate. The oxygen pressure strongly affects the morphology and the composition of films observed as a Bi:V ratio gradient along the layer deposited on the substrate. Despite BiVO4, two other phases were detected using XRD (X-ray diffraction) and Raman spectroscopy—V2O5 and Bi4V2O11. The V-rich region of the samples deposited under low and intermediate oxygen pressures was covered by V2O5 longitudinal structures protruding from BiVO4 film. Higher oxygen pressure leads to the formation of Bi4V2O11@BiVO4 bulk heterojunction. The presented results suggest that the ablation of the target leads to the plasma formation, where Bi and V containing ions can be spatially separated due to the interactions with oxygen molecules. In order to study the phenomenon more thoroughly, laser-induced breakdown spectroscopy measurements were performed. Then, obtained electrodes were used as photoanodes for photoelectrochemical water splitting. The highest photocurrent was achieved for films deposited under 1 mbar O2 pressure and reached 1 mA cm?2 at about 0.8 V vs Ag/AgCl (3 M KCl). It was shown that V2O5 on the top of BiVO4 decreases its photoactivity, while the presence of a bulk Bi4V2O11@BiVO4 heterojunction is beneficial in water photooxidation.
关键词： photoelectrochemistry,pulsed laser deposition,bismuth vanadate
更新于2025-09-23 15:19:57
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Reactive Pulsed Laser Deposition of Clustered-Type MoSx (x ~ 2, 3, and 4) Films and Their Solid Lubricant Properties at Low Temperature
摘要： We studied the tribological properties of amorphous molybdenum sulfide (MoSx) thin-film coatings during sliding friction in an oxidizing environment at a low temperature (?100 °C). To obtain films with different sulfur contents (x ~ 2, 3, and 4), we used reactive pulsed laser deposition, where laser ablation of the Mo target was performed in H2S at various pressures. The lowest coefficient of friction (0.08) was observed during tribo-testing of the MoS3 coating. This coating had good ductility and low wear; the wear of a steel counterbody was minimal. The MoS2 coating had the best wear resistance, due to the tribo-film adhering well to the coating in the wear track. Tribo-modification of the MoS2 coating, however, caused a higher coefficient of friction (0.16) and the most intensive wear of the counterbody. The MoS4 coating had inferior tribological properties. This study explored the mechanisms of possible tribo-chemical changes and structural rearrangements in MoSx coatings upon contact with a counterbody when exposed to oxygen and water. The properties of the tribo-film and the efficiency of its transfer onto the coating and/or the counterbody largely depended on local atomic packing of the nanoclusters that formed the structure of the amorphous MoSx films.
关键词： wear,molybdenum sulfides,solid lubricants,nanoclusters,reactive pulsed laser deposition,low temperature,coefficient of friction
更新于2025-09-23 15:19:57
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Space charge limited conduction in pulsed laser deposited BaTiO3/LaNiO3 hetero-junctions
摘要： We report the charge transport mechanism in BaTiO3 (BTO) thin film deposited on LaNiO3 (LNO) buffer layer using pulsed laser deposition technique thus, forming the metal – insulator – metal junction (Au/BTO/LNO). The temperature dependent Current density- Voltage (J-V) characteristics were measured, analyzed and compared with the La0.67Ca0.33MnO3 (LCMO) buffered BTO film (Au/BTO/LCMO). Although the mechanism was found to be space charge limited conduction (SCLC) as in case of BTO/LCMO but the absence of Ohmic region in Log J-Log V plot indicates higher injection rate. Various parameters such as trap density, activation energy, and ratio of free to trapped carriers (h) were extracted out from the fitted J-V plot and subsequently their temperature dependence was studied and compared with BTO/LCMO. Higher current density, lower activation energy, lower trap density and higher ratio of free to trapped carriers (h) were observed in BTO/LNO in contrast to BTO/LCMO. Furthermore, the lower activation energy indicates the presence of shallow trap level.
关键词： Non-volatile memories,Barium titanate,Metal-Insulator-Metal junction,Space charge limited conduction,Pulsed laser deposition
更新于2025-09-23 15:19:57