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The increasing demand for functional nanodevices in sustainable energy applications necessitates the development of innovative approaches. In this study, we present the fabrication and characterization of three-dimensional (3D) structures coated with titanium dioxide (TiO 2) nanorods (NRs). These novel devices are created through the integration of four distinct techniques, multi-photon lithography, post-thermal treatment, pulsed laser deposition, and an aqueous chemical growth, enabling their unique properties and functionalities in photocatalysis. The photocatalytic performance of the 3D devices is evaluated through the degradation of organic pollutants, such as methylene blue and stearic acid, showcasing their efficiency in reducing pollutant concentrations. The devices demonstrate a remarkable decomposition coefficient (k = 0.059 min − 1 ), highlighting their enhanced photocatalytic efficiency. Additionally, we propose a rapid fabrication technique using 3D holographic printing to create large-area TiO 2 -coated micro-structured photocatalytic devices at the mesoscale regime. This approach increases the active surface area, further enhancing the devices' photocatalytic capabilities. By combining additive micro-manufacturing, TiO 2 NR coating, and holographic printing, our work introduces a promising avenue for the development of advanced nanodevices with superior photocatalytic performance in sustainable energy applications. [ABSTRACT FROM AUTHOR]

Thin films of Er:YAG and Er:YAP were deposited by subpicosecond (450 fs) and nanosecond (20 ns) KrF laser (λ=248 nm) on YAG, YAP, fused silica, silicon and sapphire substrates. Laser spot size, energy density, substrate temperature and deposition ambient (vacuum and oxygen) were varied. Comparison of growth rate, morphology, composition, crystallinity and adhesion of the films grown by subpicosecond and nanosecond deposition is presented. [Copyright &y& Elsevier]

The use of composite polymeric insulators in overhead high voltage (HV) power transmission lines and in substations has been rapidly growing, as a result of their excellent operational performance, even under environmental pollution conditions. However, it has been observed that the insulation capacity of the composites deteriorates gradually for in-service insulators as a result of ageing, caused by several processes arising because of environmental, electrical and mechanical stresses. For these reasons, development of non-destructive diagnostic techniques for real-time, on-site inspection of the insulators' condition is required for ensuring high reliability of power transmission networks. To this end, laser-induced breakdown spectroscopy (LIBS) is found to offer an effective and reliable method for assessing the state of polymeric insulators, primarily silicone rubber (SIR) ones, that have been in service for up to 20 years on the HV power network of Crete, Greece. Determining the type of composite and furthermore the chemical integrity of the insulator is based on simple spectral indicators, which reflect the extent of chemical modifications induced on the insulator surface, as found in both standard and remote LIBS measurements performed in the laboratory. As a result, a stepwise diagnostic procedure was proposed and tested in an outdoors campaign, demonstrating that LIBS can become a field deployable technique for the efficient and reliable assessment of the performance of HV outdoor insulators in service. Unlabelled Image • Remote LIBS analysis of field-aged polymeric insulators has been performed on site. • A spectral indicator, R, is defined reflecting the insulator carbon-to‑silicon content. • R enables identification of the polymer composite type. • R permits assessment of the physical state of field-aged SIR insulators. • ATR-FTIR measurements support LIBS results. [ABSTRACT FROM AUTHOR]

Nanohybrids, composed of luminescent zinc oxide (ZnO) nanoparticles dispersed in an inert polydimethylsiloxane (PDMS) matrix, exhibit an excellent ability to follow changes in the type and composition of their surrounding atmosphere. These changes are found to affect the UV photoluminescence (PL) emission of the ZnO-PDMS hybrids measured at room temperature. The influence of irradiation parameters, such as excitation intensity and wavelength, on the response of the ZnO-PDMS sensor against ethanol and oxygen, have been systematically investigated in a comparative study performed employing pulsed excitation at 248 and 355 nm. This study represents the first demonstration that the sensing performance of the PL-based ZnO sensors can be optimized by tuning the excitation parameters and it particularly illustrates that maintaining a low pump energy density is crucial for enhancing the sensitivity of the sensor achieving response values approaching 100%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Uniform deposition of Ni nanoparticles on NF by PLD technique. • An optimum deposition thickness was revealed. • A 15-fold increase in ECSA of Ni-decorated NF electrodes. • Improved electrochemical values over Ni/NF electrodes. In this work, we investigated Nickel Foam (NF) electrodes decorated with Ni nanoparticles at various deposited thicknesses through the Pulsed Laser Deposition technique for the hydrogen evolution reaction (HER). Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS) were employed to gain insight into the structural and morphological characteristics of the prepared electrodes. The optimum deposition thickness was found to be 300 nm. The NF electrode decorated with 300 nm Ni nanoparticles (Ni/NF 300) exhibited improved electrochemical characteristics, i.e., reduced overpotential value s |η 10 | = 0.11 V and lower Tafel slope 99 mV dec-1, as compared to the values of 0.24 V and 134 mV dec-1, respectively, for bare NF electrode. In addition, the Ni/NF 300 electrode presents a 15-fold increase in its electrochemically active surface area (ECSA) in comparison to an NF electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] • Laser-nanostructuring of Nickel and iron electrodes. • Increased double layer capacitance values of Ni-Fe laser-nanostructured electrodes. • Enhanced OER and HER values of Ni-Fe laser-nanostructured electrodes. There is an increasing interest in developing an Ni-Fe supercapacitor-electrolyser system (SCES) for electricity storage and efficient hydrogen production. In this study, periodic nanostructures on nickel [(λ Ni = 570 ± 30) nm] and on iron sheets [(λ Fe = 553 ± 6) nm] have been fabricated and were used as electrodes in an alkaline SCES. Their efficiency was compared to untreated nickel and iron sheets. The electrochemical evaluation of the nanostructured electrodes showed lower overpotential (η 10 and η 100) and lower Tafel slope for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The hydrogen production efficiency of the laser-nanostructured electrodes was significantly enhanced. Moreover, the laser-nanostructured electrodes' double-layer capacitance (C DL) values were increased 1.5 times for laser-nanostructured Fe electrodes and 5.3 times for laser-nanostructured Ni electrodes. These results show the potential of the fabricated electrodes in applications serving a dual purpose, i.e., enhanced hydrogen production and increased charge storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • HER efficiency depended on electrodeposition time. • Facile and time-effective one-step electrode fabrication. • 50% enhanced hydrogen production compared to untreated electrodes. • 6.5 times higher ECSA of electrodeposited Ni foam. Nickel foam electrodes were treated with a facile and cost-effective electrodeposition method to increase the hydrogen production efficiency in alkaline electrolysis setups. The treated electrodes (Electrodeposited Nickel Foam – ENF) exhibit enhanced electrochemical values compared to a bare nickel foam electrode (NF). A comprehensive analysis is presented on how the electrodeposition time determines the kinetics of hydrogen evolution reaction (HER) and the electrochemical values of the ENF electrodes. It was revealed that deposition time plays a decisive role in the total hydrogen production efficiency. In particular, the ENF electrode with 10 min of electrodeposition, presents a lower Tafel slope, lower overpotentials (|η 10 |=135 mV, |η 100 | = 230 mV), and enhanced hydrogen production (1.5 times higher) compared to an NF electrode. The improved characteristics are mainly attributed to the increased electrochemically active area (6.5 times higher than the NF electrode). Field emission scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used for the structural and morphological analysis of the electrodeposited nickel foam electrodes. [ABSTRACT FROM AUTHOR]

In view of the demand for high-quality thermal neutron detectors, boron films have recently attracted widespread research interest because of their special properties. In this work, we report on the deposition of boron films on silicon substrates by sub-picosecond pulsed laser deposition (PLD) at room temperature. Particular emphasis was placed on the investigation of the effect of the laser energy density (fluence) on the ablation process of the target material, as well as on the morphological properties of the resulting films. In addition, based on the study of the ablation and deposition rates as a function of the fluence, the ablation/deposition mechanisms are discussed. We show that well-adherent and stable boron films, with good quality surfaces revealing a good surface flatness and absence of cracks, can be obtained by means of the PLD technique, which proves to be a reliable and reproducible method for the fabrication of thick boron coatings that are suitable for neutron detection technology. [ABSTRACT FROM AUTHOR]

In the present work, a novel approach has been employed to effectively enlarge the electrocatalytic area of the electrodes in an alkaline electrolysis setup. This approach consists of a two-step electrode fabrication process: In the first step, ultrashort laser pulses have been used to nanostructure the electrode surface. In the second step, electrodeposition of nickel particles was performed in a modified Watt's bath. The resulting electrodes have been found to exhibit a significantly increased hydrogen evolution reaction (HER) activity. Compared to the laser-nanostructured electrode (LN) and an untreated (i.e., flat) electrode, the electrodeposited-laser-nanostructured (ELN) electrode provides (i) enhanced electrochemical values (ii) a significant increase of double-layer capacitance (C DL) (values up to 1945 μF cm−2) compared to that of an LN electrode (288 μF cm−2) (iii) higher J peaks at CVs sweeps and (iv) lower Tafel slopes (−121 mV dec−1 compared to −157 mv dec−1). The ELN electrode provides an overpotential value of |η| 100 = 264 mV, which shows a noteworthy 34% decrease compared to a flat Ni electrode and a 15% decrease to an (LN) electrode. Scanning electron microscopy (SEM) revealed that the electrodeposition of nickel on the LN nickel electrodes results in a dendrite-like morphology of the surface. Thus, the enhancement of the HER has been attributed to the dendrite-like geometry and the concomitant enlargement of the electrocatalytic area of the electrode, which presents an electrochemical active surface area (ECSA) = 97 cm−2 compared to 2.8 cm−2 of the flat electrode. The electrodes have also been tested in actual hydrogen production condition, and it was found that the ELN electrode produces 4.5 times more hydrogen gas than a flat Ni electrode and 20% more hydrogen gas than an LN electrode (i.e. without the extra nickel electrodeposition). [Display omitted] • Two-step Ni electrode fabrication process; laser nanostructuring and electrodeposition of Ni particles. • Enhanced hydrogen production up to 4.5 times in alkaline electrolysis using Electrodeposited-Laser-Nanostructured Ni substrates. • Electrochemical evaluation for HER, providing improved values of Tafel slope (b = −121.3 mV dec−1), overpotential values of η 10 = 108 mV and η 100 = 264 mV and ECSA = 97 cm−2. [ABSTRACT FROM AUTHOR]

This study describes the fabrication of ultrafast laser-induced periodic nanostructures on Nickel sheets and their use as cathodes in alkaline electrolysis. For the first time, to the best of our knowledge, laser-nanostructured Ni sheets were used as cathode electrodes in a custom-made electrolysis cell at actual, Hydrogen producing conditions, and their efficiency has been compared to the untreated Nickel sheets. The electrochemical evaluation showed higher J peaks , lower overpotential, and enhanced double-layer capacitance for the nanostructured electrode. A decrease in the Tafel slope was also found for the nanostructured electrode. The hydrogen production efficiency was found to be 3.7 times larger for the laser-nanostructured Nickel electrode, which was also confirmed by current-time measurements during electrolysis. Also, a novel approach is proposed to improve the stability of the current density during electrolysis and, therefore, the hydrogen production process by about 10%. [Display omitted] • Laser nanostructured Ni electrodes produce higher values of hydrogen gas. • An Electrochemical evaluation of laser nanostructured Ni electrodes. • A Correlation between electrical measurements and hydrogen production during electrolysis. [ABSTRACT FROM AUTHOR]

Lead halide perovskites are currently widely investigated as active materials in photonic and optoelectronic devices. While the lack of long term stability actually limits their application to commercial devices, several experiments demonstrated that beyond the irreversible variation of the material properties due to degradation, several possibilities exist to reversibly modulate the perovskite characteristics by acting on the environmental conditions. These results clear the way to possible applications of lead halide perovskites to resistive and optical sensors. In this review we will describe the current state of the art of the comprehension of the environmental effects on the optical and electronic properties of lead halide perovskites, and of the exploitation of these results for the development of perovskite-based sensors. [ABSTRACT FROM AUTHOR]

We performed a comparative study of the plasma generated from AlN targets under sub-ps vs ns UV (λ = 248 nm) excimer laser pulses. Optical emission and time-of-flight spectra recorded in cases of samples irradiated with ns laser pulses showed the presence of Al lines, which became prevalent after the first laser pulse was incident on the target. These observations are congruent with the metallization of AlN targets inside each crater under multipulse ns laser action at laser fluences above the ablation threshold, observed by visual inspection and optical microscopy. Metallization was not observed when working with sub-ps laser pulses. Moreover, our studies confirmed the predominant presence of AlN positive molecular ions in the plasma generated in front of AlN targets submitted to sub-ps multipulse laser irradiation. The optical emission data are in good agreement with time-of-flight mass analysis. We emphasize that all investigations support the experimental evidence reported by György et al. [E. György et al., J. Appl. Phys. 90, 456 (2001)], according to which thin films obtained by pulsed laser deposition with ns laser pulses contain a significant amount of metallic Al, while only AlN is detected in films obtained with sub-ps laser pulses. Measurements of the velocity and kinetic energy distributions of AlN[sup +] indicate that in the case of ns-laser ablation the ions are emitted with thermal energy, while in the case of sub-ps-laser ablation a bimodal distribution exists and has thermal (1 eV) and hyperthermal (10 eV) energy components. This points to different plasma formation mechanisms for the two cases. [ABSTRACT FROM AUTHOR]

We investigated the relative merits and limits of pulsed laser deposition from AlN targets in vacuum and low-pressure nitrogen in obtaining stoichiometric and crystalline aluminum nitride thin films. We used two UV excimer laser sources (λ=248 nm): a nanosecond system (τ[sub FWHM]=30 ns) and, a subpicosecond (τ[sub FWHM]=450 fs) system. The obtained structures were characterized by x-ray diffraction, electron microscopy in cross section, selected area electron diffraction, and profilometry. We demonstrated that the best results are obtained with the sub-ps laser source in vacuum and in low pressure nitrogen when the AlN thin films are very pure, crystalline, clearly exhibiting a tendency to epitaxy. Metallic Al is present in the films deposited with the ns laser source. We believe this is an effect of the gradual decomposition of AlN inside the crater on the target surface under multipulse laser irradiation. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Even if it has been recently assessed that sub-picosecond ablation is not a “melting-free” process, a systematic investigation of the issue of droplets is still lacking. In this paper we discuss the effects of fluence (F = 0.3, 1, 3 J/cm 2 ), target-substrate distance (d TS = 5, 6, 7, 8, 9 cm) and number of laser pulses per site (N p/s = 2, 12, 22, 36, 96) on the morphology in terms of droplets and plasmonic response of gold nanoparticles deposited by sub-picosecond pulsed laser ablation. Among metals, gold is an ideal candidate to study the occurrence of droplets due to its low electron-phonon coupling that favors the appearance of heat affected zones. Our findings demonstrate that N p/s affects the production of large droplets more intensely than F and d TS . In fact, increasing N p/s produced much larger droplets than the ones obtained by tuning the fluence and an increment in the droplet density of 10 times. On the other hand, while the maximum density of small droplets (average diameter ≤ 0.15 μm) occurs at F = 1 J/cm 2 (with respect to 0.3 J/cm 2 and 3 J/cm 2 ), the total droplet density exhibits a minimum at such fluence. [ABSTRACT FROM AUTHOR]