Nikša Krstulović

This study presents a novel, chemical-free approach for the synthesis of Ag-modified TiO ₂ (Ag@TiO ₂ ) nanoparticles by combining the two laser-based ablation techniques pulsed laser deposition (PLD) and pulsed laser ablation in liquids (PLAL). Initially, silver was ablated using 200 and 2000 pulses and deposited onto titanium targets via PLD. Subsequently, these modified targets were submerged in water and processed using PLAL to generate the final nanomaterials. Characterization through HRTEM, EDS, and UV–vis spectroscopy confirmed the formation of nanoparticles with a predominantly anatase TiO ₂ phase. The synthesized particles exhibited spherical morphology, with average diameters ranging from 97–331 nm for the 200p sample and 86–144 nm for the 2000p sample. The photocatalytic efficiency was evaluated using rhodamine B (RhB) under UV irradiation; while RhB showed minimal self-degradation, the Ag@TiO ₂ 200p and 2000p NPs samples achieved degradation rates of 75.8% and 88.4%, respectively. The main novelty of this work is the combination of two laser techniques in a chemical-free process, which provides an efficient and environmentally friendly route for the fabrication of Ag@TiO ₂ photocatalysts.

Various metal-modified titanium dioxide (TiO₂) nanotubes have been widely investigated for water purification due to their large surface area, stability, and photocatalytic activity. In this context, this study investigates the deposition of vanadium-based nanoparticles (V NPs) on TiO₂ nanotubes via immersion in aqueous dispersions of V NPs synthesized by picosecond and nanosecond pulsed laser ablation in liquid at four different output energies (picosecond: 15 and 30 mJ; nanosecond: 120 and 250 mJ), with the aim of improving their photocatalytic performance. By optimizing the concentration of V NPs in the dispersions and the immersion time, the degradation efficiency of Acid Yellow 23 under photocatalytic conditions was enhanced for TiO₂ modified with V NPs synthesized at output energies of 30 and 250 mJ, whereas no improvement was observed for TiO₂ modified with V NPs synthesized at 15 and 120 mJ. A series of V-TiO₂ photocatalysts was fabricated by depositing laser-synthesized V NPs of various sizes on TiO₂ nanotubes prepared by electrochemical anodization of a titanium mesh.

In this study, for the first time, ZnO nanoparticles doped with noble metals (Pt, Ag, Au) were employed as a solid contact in nitrate ion-selective electrodes based on a glassy carbon internal electrode, and their performance was described and studied. Nanoparticles were synthesized by pulsed laser ablation in liquid. They were placed as an intermediate layer between the inner electrode and the ion-selective membrane. The impact of nanoparticle type on electrode performance was assessed by analyzing their analytical and electrical parameters using both potentiometry and electrochemical impedance spectroscopy. It was found that the determined properties of hybrid nanoparticles, as well as their effectiveness as a solid contact, depend significantly on the type of metal doping. Doping ZnO nanoparticles with metals increases their electrical capacity and reduces contact angles. The best results were obtained for the electrode modified with platinum-doped zinc oxide nanoparticles, characterized by the largest electric capacitance and the most hydrophobic properties among the hybrid nanoparticles. This electrode has been successfully used for the potentiometric determination of nitrate content in soil.

To achieve sustainable extractions, this study examines the impact of different extraction methods to utilize waste from the sugar industry. In addition to conventional thermal extraction, the impact of high-power ultrasound (US) and high-voltage electrical discharge (HVED)-assisted extractions on the yield of bioactive compounds and the antioxidant capacity (AC) value of sugar beet leaf extracts was determined. US extraction proved to be an excellent method for extracting bioactive compounds, while HVED extraction proved to be an excellent method for extracting Vitexin. AC was measured both spectrophotometrically (DPPH and FRAP) and spectroscopically via electron spin resonance (ESR). The AC results correlate with each other, and the highest AC values were found in the US-treated samples with 25% ethanol solution as the extraction solvent. Characterization of the plasma via optical emission spectroscopy (OES) showed that neither the solvent nor the sample influenced the plasma spectra, only the gas used (nitrogen/argon). All of the obtained results provide an excellent basis for future research into the utilization of food waste and by-products.

With recent technological advances and the growing interest in environmentally friendly fiber production processes, the textile industry is increasingly turning to the spinning of filaments from recycled raw materials in the melt spinning process as the simplest method of chemical spinning of fibers. Such processes are more efficient because the desired active particles are melt-spun together with the polymer. The study investigates the melt spinning of recycled polyamide 6 (PA 6) fibers modified with zinc oxide nanoparticles (ZnO NPs) in concentrations ranging from 0.1 to 2.0 wt% of the polymer. The extrusion process was optimized under laboratory conditions. An analysis of the effectiveness of the nanoparticle distribution and chemical composition was performed using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The results of the thermal analysis show an increase in the glass transition temperature of the extruded material from 50.97 °C (raw polymer) to 51.40 °C to 57.98 °C (polymer modified with ZnO NPs) and an increase in the crystallization point from 148.19 °C to a temperature between 175.61 °C and 178.16 °C, while the molar enthalpy (ΔHm) shows a decreasing trend from 65.66 Jg⁻¹ (raw polymer) to 48.23 Jg⁻¹ (PA 6 2.0% ZnO). The FTIR spectra indicate PA 6 polymer, with a characteristic peak at the wavelength 1466 cm⁻¹, but pure ZnO and PA 6 blended with ZnO show a characteristic peak at 2322 cm⁻¹. The distribution of nanoparticles on the fiber surface is more or less randomly distributed and the different size of NPs is visible. These results are confirmed by the EDS results, which show that different concentrations of Zn are present. The mechanical stability of the extruded polymer modified with NPs is not affected by the addition of ZnO NPs, although the overall results of strength (2.56–3.22 cN/tex) and modulus of elasticity of the polymer (28.83–49.90 cN/tex) are lower as there is no drawing process at this stage of the experiment, which certainly helps to increase the final strength of the fibers. The results indicate the potential of modification with ZnO NPs for further advances in sustainable fiber production.

This study proposes a simple and controlled method for producing TiO₂ with phase junction, oxygen vacancies, and Ti³⁺ by combining picosecond pulsed laser irradiation and electrochemical anodization. Ti mesh was pretreated by irradiating with a picosecond pulsed laser technique using an Nd:YAG laser (1064 nm) at two fluencies, 15 J/cm² and 30 J/cm². The samples were then subjected to electrochemical anodization to form TiO₂ nanotube arrays on the previously laser-treated surface. This study will investigate the possibility of forming TiO₂ nanotube arrays on a pre-laser-treated Ti substrate and determine their physicochemical and photocatalytic properties. The samples were characterized by FESEM, XRD, Raman, XPS, and UV-Vis DRS. UV-Vis spectroscopy was used to observe the progress of photocatalytic degradation for all samples, and degradation products were determined using GC-MS. With the synergistic effects of phase junction, oxygen vacancies, and Ti³⁺, the laser-treated TiO₂ with 30 J/cm² showed a higher photocatalytic degradation rate (85.1%) of the pesticide carbofuran compared to non-laser-treated TiO₂ (54.8%), remaining stable during successive degradation cycles, which has promising practical applications.