Journal of Nanoparticle Research最新文献

The present study evaluates the structural transformation of niobium pentoxide (Nb₂O₅) through reaction with sodium hydroxide (NaOH) under hydrothermal conditions, focusing on the effects of temperature and reaction time on its crystalline morphology. In this parametric study, Nb₂O₅ particles were reacted with NaOH at 160 °C and 180 °C temperatures and reaction times of 90, 120, and 180 min. The resulting materials were characterized by X-ray diffraction (XRD), laser diffraction particle size analysis (LDPSA), specific surface area analysis (BET), and scanning electron microscopy (SEM). XRD confirmed the formation of NaNbO₃ and highlighted changes in the crystalline structure. LDPSA showed particle size redistribution due to the reaction conditions. BET analysis revealed significant surface area enhancements, with the sample treated at 180 °C for 90 min achieving the highest value. SEM images confirmed morphological changes induced by temperature and reaction time. These results underscore the importance of precise control over synthesis parameters to optimize the textural and structural properties of niobium oxide for advanced applications, such as active polymer packaging systems, catalysis, adsorption, and biomedicine.

A reducing agent–free AuNP synthesis approach in an alkaline aqueous medium was optimized using the design of experiments (DoE) to improve batch-to-batch reproducibility. A Box–Behnken design was employed to investigate the effects of Au³⁺ concentration, NaOH concentration, stirring, and temperature on AuNP formation. The significant variables identified in the model, which described absorbance and Ψ responses, included the concentrations of Au³⁺ and NaOH, as well as the interaction of NaOH with stirring and temperature. Using the desirability function, the system was optimized to produce more concentrated AuNP with reduced polydispersity, yielding optimal parameters of 200 µM Au³⁺, 4.75 mM NaOH, 130 °C, and 350 rpm. The revised synthesis method demonstrated excellent batch-to-batch reproducibility of AuNP. The optimized AuNP were predominantly spherical, with a mean particle diameter of 18.66 ± 4.78 nm by TEM and a hydrodynamic diameter of 19.8 ± 0.9 nm with a polydispersity index of 0.208 by DLS. Complementary control experiments supported the importance of the alkaline medium for AuNP formation and indicated that temperature influences the rate of AuNP formation. This methodology provides a straightforward approach for producing “naked” AuNP with consistent batch-to-batch reproducibility.

Graphical abstract

Sr₂SiO₄:xCe³⁺ nanophosphors were prepared by the sol-gel method and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet reflectance spectroscopy, and photoluminescence spectroscopy. XRD analysis confirmed the presence of both α- and β-phases of Sr₂SiO₄, and that Ce³⁺ was successfully incorporated into the host matrix. Crystallite size and micro-strain were estimated, indicating short-range crystalline order with minimal lattice distortion. The excitation and emission spectra showed that the phosphors can be effectively excited at 271 nm and emit blue-green light with a peak at 468 nm, corresponding to the 5d→4f allowed transition of Ce³⁺ ions. The Ce³⁺ concentration quenching process was also investigated, and the mechanism was identified as a possible dipole-dipole transition. Additionally, zero phonon energy and Stokes shift were determined. CIE coordinates and colour purity were evaluated from the emission data. These preliminary findings indicate that the prepared Ce³⁺-doped nanophosphors are promising candidates for solid-state lighting applications, pending further studies of quantum yield and prototype devices.

Optimizing TiO₂ nanotube/nanoring (NT/NR-TiO₂) systems with graphene derivatives is a powerful strategy to enhance solar-driven water treatment, yet their performance under aggressive acidic conditions remains underexplored. This study evaluates the synthesis, interfacial properties, and artificial solar-driven methylene blue (MB) degradation of GO- and rGO-modified NT/NR-TiO₂ architectures. SEM and XRD confirmed well-defined, highly crystalline anatase arrays. The average crystallite size from the anatase (101) reflection was 20.36 nm for pristine NT/NR-TiO₂, decreasing to 17.42 nm and 18.64 nm for GO and rGO modifications, respectively. Photoelectrochemical profiles and Mott-Schottky analysis revealed that the NT/NR-TiO₂-GO composite achieved the highest photocurrent response. This performance was driven by an optimized potential drop, suppressed electron-hole recombination, and strong π-π surface interactions under extreme acidic conditions (pH 1). Consequently, the GO-modified photoanode delivered a superior MB degradation efficiency of 85% within 120 min (k_app = 1.53 × 10^–2 min⁻¹), outperforming both rGO-modified and pristine counterparts. Importantly, this was accompanied by a 78.6% reduction in chemical oxygen demand, demonstrating extensive partial oxidation into lower-molecular-weight fragments. Furthermore, the composite displayed robust operational reusability, retaining 80% efficiency after 5 consecutive cycles (600 min total). These findings confirm its high stability and potential for the direct treatment of acidic industrial effluents without preliminary neutralization steps.

Graphical abstract

Magnetic nanoparticles were successfully modified with a thin layer of molecularly imprinted polymers (MIPs) via the admicellar polymerization technique for the selective removal of methylene blue (MB) from real water samples. The chemical and morphological properties of the synthesized materials were comprehensively characterized using Fourier Transform Infrared Spectroscopy–Attenuated Total Reflectance (FTIR–ATR), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM). The adsorption kinetics were better described by the pseudo-second-order kinetic model (R² > 0.99), indicating that the adsorption process was mainly governed by chemical interactions. The maximum binding capacity of the MB-imprinted polymer-modified magnetic nanoparticles was determined to be 5.64 mg g⁻¹ (95% CI: 6.76–4.52 mg g⁻¹). Equilibrium adsorption data showed a better fit to the Freundlich isotherm model (R² > 0.99), suggesting heterogeneous adsorption behaviour, which is characteristic of molecularly imprinted systems. The prepared adsorbent exhibited excellent reusability and maintained its adsorption performance over seven consecutive adsorption–desorption cycles without significant efficiency loss. The imprinting factor for MB was calculated as 7.18, while lower values were obtained for methylene violet (3.11) and indigo carmine (1.97), demonstrating the high selectivity of the imprinted cavities toward the template molecule. Moreover, the selectivity coefficients (k) for methylene violet (2.41) and indigo carmine (3.18) confirmed the preferential recognition of MB over competing dye molecules. The optimum adsorption conditions were determined as pH 7 and an incubation time of 35 min. The applicability of the developed MIP-based magnetic adsorbent was further validated using real water samples collected from different natural sources. The findings highlight the novelty and potential of the proposed system as a selective, reusable, and efficient adsorbent for wastewater treatment applications.

This study investigated the effect of glycine concentration on the physicochemical properties of zero-valent iron nanoparticles (NPs-Fe) synthesized by chemical reduction. XRD results showed that Fe⁰ with a body-centered cubic (BCC) structure remained the predominant crystalline phase after functionalization, while the crystallite size decreased progressively from 9.55 to 5.54 nm as the glycine concentration increased. In contrast, SEM analysis showed an increase in the average particle diameter from 58.95 ± 12.80 nm for NPs -Fe to 75.51 ± 18.30, 83.36 ± 27.60, and 83.79 ± 29.50 nm for NPs-FeG1, NPs-FeG2, and NPs-FeG3, respectively. Chain-like structures were observed in all samples; their formation may be associated with dipole–dipole magnetic interactions and surface interactions between the nanoparticles. The FTIR results were consistent with the interaction of glycine with the surface of the NPs-Fe and with the presence of surface species of iron oxides and oxyhydroxides. The effect of glycine on the zeta potential depended on its concentration; NPs-Fe-G1 exhibited the highest absolute value, while higher concentrations did not produce any further improvement in colloidal stability. TGA/DSC thermogravimetric analyses showed that glycine modifies the thermal behavior of the nanoparticles, while Raman analysis of the thermally treated residues revealed the presence of iron oxide and iron oxyhydroxide species. Overall, the results show that the glycine concentration influences the growth of crystallites, particle size and morphology, surface characteristics, colloidal behavior, and thermal response, without altering the BCC structure of Fe⁰. These results contribute to our understanding of the effect of glycine as a surface modifier of zero-valent iron nanoparticles and provide a foundation for further studies in areas such as environmental remediation, catalysis, detection, and biomedical applications.

Graphical Abstract

Surface reflection reduces the amount of light reaching the solar cell and can lower its photovoltaic performance. Therefore, antireflection coatings are important for reducing optical losses and improving the solar cell performance. In this study, ZnO/PMMA films were coated on the cover glass of the solar cell using a sol-gel dip-coating technique. PMMA was added to the ZnO matrix as a porogen to form porous ZnO films. The effect of PMMA concentration in the dip-coating solution on optical properties, crystal and chemical structure, and photovoltaic conversion efficiency was investigated. XRD and FTIR analyses proved that ZnO was successfully obtained both alone and in the presence of PMMA. In addition, FESEM and optical microscopy images revealed that the pores on the surface were observed to increase as the PMMA content of the ZnO/PMMA film increased. ZnO/PMMA coated glass slides exhibited higher transmittance, lower reflectance and refractive index values in the visible wavelength range compared to pure ZnO coated glass slides. Among the investigated samples, the film containing 3 wt.% PMMA exhibited the most favorable combination of optical and photovoltaic properties. The UV-Vis spectrum showed a maximum transmittance of 92.50%, a lowest reflectance of 6.35% and a lowest refractive index value of 1.64 at a wavelength of 650 nm with the PMMA/ZnO film containing 3 wt.% PMMA on a glass slide. Adding the PMMA phase to the ZnO film resulted in approximately a 6% increase in solar cell efficiency. The pore formation mechanism of PMMA could be attributed to the aforementioned improvement in the light transmittance and photovoltaic conversion efficiency. The present findings demonstrated that the addition of PMMA provided a simple solution-based route to modify the porosity, refractive index, optical transmittance/reflectance, and photovoltaic performance of ZnO films. Therefore, ZnO/PMMA coatings might represent a promising alternative approach for antireflection applications in silicon solar cells.

The prevalence of antimicrobial resistance has intensified the need for alternative approaches to overcome the limitations of conventional drugs. Photodynamic inactivation (PDI), in which photosensitizers (PSs) generate reactive oxygen species upon light activation, has emerged as a promising strategy by inducing multi-target microbial damage. Nevertheless, low water solubility, aggregation, and limited performance of many molecular PSs, especially in complex environments such as biofilms, can reduce PDI efficacy. This review examines applications of inorganic nanoparticles (iNPs) in the PDI of bacteria and fungi, integrating fundamental principles, physicochemical properties, and biological interactions with PDI outcomes. Illustrative examples include silver nanoparticles associated with Zn(II) porphyrins, which enabled PDI-mediated eradication of Candida albicans at ~ 4- to 8-fold lower PS concentrations, whereas the PS alone caused a reduction of ~ 2–3 log₁₀, and a silica-based platform that decreased Rose Bengal dark toxicity in Escherichia coli, increasing viability from ~ 43 to 83–99%. Conversely, Ag-doped TiO₂ induced ~ 30% C. albicans reduction even without irradiation, indicating light-independent antimicrobial activity. These and other examples are reported in the review, which shows that iNPs can broaden the scope of PDI applications through distinct and complementary mechanisms. Challenges, however, remain, such as variability in experimental parameters and data reporting, which may limit the interpretation of reported outcomes, along with limited fungal model diversity and incomplete mechanistic understanding, important aspects for clinical translation. Overall, this review outlines advances and challenges in the field, providing insights to guide the development of improved iNP-based platforms for antimicrobial photodynamic applications.

Graphitic carbon nitride (g-C₃N₄), a promising photocatalyst, holds wide applications in sulfate radical (SO₄^•⁻)-based advanced oxidation processes. Unfortunately, its practical utilization is still restricted by poor conductivity and severe recombination of photogenerated charge carriers. Herein, a two-step calcination strategy is put forward to boost the photocatalytic performance by constructing CN/BCN homojunction, where CN refers to the urea-based g-C₃N₄ and BCN denotes the melamine-derived boron-doped g-C₃N₄ with two-step calcination. Boron doping endows BCN with narrowed band gap and red-shifted light absorption edge. Meanwhile, the CN/BCN homojunction achieves low electrochemical impedance, optimal photocurrent response, and appropriate charge carriers capture capability. Tetracycline (TC) removal efficiency reaches 98.6% by CN/BCN accompanied with potassium persulfate (K₂S₂O₈) under visible light irradiation for 60 min, along with the corresponding kinetic rate constant being 0.0748 min⁻¹. Over five consecutive cycling tests, TC removal efficiency stays still higher than 90.0%. In addition, the common coexisting anions exert minor effect on its photocatalytic performance. As for the persulfate-based CN/BCN photocatalytic system, SO₄^•−, ^•OH, ^•O₂⁻ and photogenerated holes (h⁺) all serve as active radicals for TC removal, with their relative contribution levels as SO₄^•− < ^•OH < ^•O₂⁻ < h⁺.