Journal of Nanoparticle Research最新文献

This study addresses the challenge of platinum degradation due to carbon support corrosion in proton exchange membrane fuel cells (PEMFCs) by presenting an approach for the direct immobilization of Pt nanoparticles onto rice-husk-derived bio-nanosilica. This strategy aims to overcome limitations associated with traditional Pt/C catalysts, which suffer from carbon support oxidation and catalyst migration under operating conditions. The work describes the synthesis methodology for Pt/SiO₂-C via amine functionalization of bio-nanosilica, followed by chemical reduction of platinum precursors and incorporation with conductive carbon materials to maintain electronic conductivity. The resulting Pt/SiO₂-C1 (6:1) catalyst shows promising oxygen reduction reaction (ORR) activity with an onset potential of 0.87 V vs RHE at a low Pt loading of 3.3 wt.%, indicating good mass activity performance. Additionally, accelerated durability tests conducted under fuel cell operating conditions show improved kinetic activity and stability with a positive shift of 10 mV in half-wave potential after a 5000-cycle load test, suggesting better catalyst retention compared to conventional systems. This work explores a potential avenue for designing sustainable electrocatalysts for PEMFCs, addressing a materials challenge while utilizing renewable biomass-derived support materials. The approach shows promise for the development of more durable fuel cell catalysts with improved stability characteristics.

The search for new thermoelectric (TE) materials has promoted the vast studies of low-dimensional carbon-based nanostructures due to their tunable electronic and thermal transport properties. In the following, we will examine the theoretical study of thermoelectric properties of single-walled CNTs by ZnO dimer dopant using the density functional tight-binding (DFTB) calculations beyond NEGF formalism. From electronic band structure analysis, it was shown that ZnO dimers created localized states around the Fermi level and led to charge carrier transport. These modifications did not affect the strong electrical conductance but enhanced the Seebeck coefficient dramatically. The simulated lattice thermal conductance is also lower, possibly as the phonons were scattered by the dopants. In combination, these have led to a better thermoelectric figure of merit (ZT). These findings demonstrate ZnO dimer doping as a novel approach for tuning thermoelectric properties and open up new avenues in nanoscale energy-saving applications.

We investigate theoretically a hydrogen sensor based on a one-dimensional core–shell nanoparticle chain. The nanoparticles are composed of silver cores coated with palladium (Pd) shells. The distance between adjacent particles is larger than three times the unit radius. This configuration allows for the analysis of the optical response of the designed structure using both coupled dipole theory (CD) and the finite-difference time-domain (FDTD) method. Leveraging the change in the dielectric constant of Pd before and after hydrogen absorption, combined with the collective effects of surface plasmons, the presence of H₂ is detected through differences in the absorption cross-sections. Results show that by constructing nanoparticle chain models with varying periods or particle sizes, Wood’s anomaly and ultra-narrow absorption cross-sections are observed both before and after H₂ absorption. Furthermore, the difference in the absorption cross-sections still exhibits Wood's anomaly and ultra-narrow absorption cross-sections. These effects are attributed to the long-range interactions between individual and collective interactions within the unit structures, which can be directly predicted by CD theory. The maximum of the difference absorption cross-sections would be reach to 16.7% when the concentrate of H₂ changes 4%. The occurrence of Wood's anomaly and ultra-narrow absorption peaks in the absorption spectral difference can effectively indicate the presence of hydrogen in the structure, thereby reflecting the characteristics of hydrogen sensing from another perspective.

Core–shell nanoclusters have emerged as promising candidates for gas-sensing applications due to their tunable electronic structures. In this work, the CO sensing potentials of Ag@Au, Pd@Au, and Ag@Pd core–shell nanoclusters were systematically investigated using quantum chemical calculations. Key electronic descriptors, including ionization potential, electron affinity, global electrophilicity index, HOMO–LUMO energy gap, and projected density of states, were analyzed. The results reveal that Au-shell nanoclusters (Ag@Au and Pd@Au) retain high electrophilicity and electronic stability, closely resembling monometallic Au, while allowing modulation through core substitution. In contrast, the Pd-shell Ag@Pd cluster exhibits reduced electrophilicity, narrower HOMO–LUMO separation, and enhanced electronic flexibility. CO adsorption studies demonstrate that Ag@Au and Pd@Au favor moderate, C-end adsorption with comparable interaction energies governed by the Au shell, whereas Ag@Pd supports multiple adsorption configurations, including a strongly chemisorbed multi-centered state with pronounced charge transfer and π-backdonation. The combined electronic and adsorption analyses highlight the critical role of core–shell architecture in governing charge-transfer behavior and interaction strength, providing insights into the rational design of bimetallic nanoclusters for CO gas sensing applications.

MgFe₂O₄ spinel ferrites have attracted increasing interest as magnetically recyclable photocatalysts owing to their narrow bandgap (~ 1.9 eV) and structural robustness; however, their photocatalytic efficiency is often limited by rapid charge‐carrier recombination. In this work, Mg_1-xZn_xFe₂O₄ (x = 0–0.15) photocatalysts were synthesized via co-precipitation route, and the combined effects of Zn²⁺ doping and calcination temperature (700–900℃) on their structural, optical, and photocatalytic properties were systematically investigated using a full factorial experimental design. XRD and TEM analyses confirm the successful incorporation of Zn²⁺ into the spinel lattice without secondary phase formation, accompanied by enhanced crystallinity at elevated calcination temperatures. UV–Vis diffuse reflectance spectra reveal a modest enhancement of visible-light absorption (600–800 nm) with increasing Zn²⁺ content, while the fundamental bandgap slightly widens from 1.88 eV (undoped) to 1.95–1.98 eV upon Zn²⁺ substitution. Photocatalytic degradation of methylene blue under UV irradiation demonstrates a distinct global performance maximum at x = 0.10 and 800 °C, yielding a degradation efficiency of 97.23% and an apparent rate constant of 0.0402 min⁻¹, which is ~ 1.56 times higher than that of undoped MgFe₂O₄ under identical conditions. Radical scavenging experiments indicate that hydroxyl radicals are the dominant reactive species, predominantly generated via electron-mediated oxygen reduction pathways. The observed enhancement arises from a non-additive, synergistic interaction between Zn²⁺-induced electronic modulation and temperature-controlled crystallinity, rather than from surface area or bandgap narrowing alone. This study provides quantitative evidence for synergistic optimization in doped spinel ferrites and offers guidance for the rational design of efficient, recyclable magnetic photocatalysts.

The synthesis of iron oxide nanoparticles (IONPs) with a narrow size distribution (PDI < 0.2 in DLS) with tailored physicochemical properties remains a significant challenge in the field of nanotechnology for biomedical applications. This study presents a droplet-based microfluidic platform for the continuous synthesis of Magnetite (Fe₃O₄) nanoparticles through co-precipitation under strongly alkaline conditions (pH = 12.3), without the use of surfactants. By optimizing precursor concentrations (0.75% FeSO₄·7H₂O and 1.2% FeCl₃·6H₂O for sample C2), we successfully produced IONPs with a hydrodynamic diameter of approximately 25 nm, as confirmed by dynamic light scattering (DLS). A comprehensive characterization approach was employed, utilizing a variety of analytical techniques including X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). This multifaceted approach yielded several significant findings. First, the analysis indicated high crystallinity, characterized by narrow size distributions with a mean diameter ranging from 17 to 31 nm. Second, the study identified superparamagnetic behavior, with saturation magnetization (Ms) values between 63 and 72 emu g⁻¹. Sample C2 was found to exhibit a balanced trade-off between structural and magnetic characteristics, making it a promising core candidate for further functionalization and application-specific evaluation, once appropriate surface modification and functional performance testing are implemented. This microfluidic approach enhances mixing uniformity and hydrodynamic reproducibility within droplet microreactors, enabling consistent nucleation–growth conditions and scalable production of Fe₃O₄ nanoparticles with narrow size distribution in colloidal dispersion (PDI < 0.2 by DLS).

A highly sensitive and recyclable surface-enhanced Raman scattering (SERS) substrate was successfully fabricated through in situ reduction of bimetallic gold-silver nanoparticles (Au–Ag NPs) on vertically aligned titanium dioxide nanorods (TiO₂ NRs) grown on porous silicon (PS). The as-prepared Au–Ag/TiO₂/PS substrate demonstrated exceptional SERS performance for the detection of crystal violet (CV), reaching a low detection limit (LOD) of 10^–11 M and a high enhancement factor (EF) of 1.74 × 10⁷. This superior performance can be attributed to the synergistic effect of the appropriately sized Au–Ag NPs with nanoscale interparticle gaps that generate intense localized surface plasmon resonance (LSPR), as well as the large surface area of PS, which facilitates analyte enrichment. Moreover, the substrate exhibited excellent photocatalytic self-cleaning capability under UV irradiation. The rapid generation of non-equilibrium carriers within the TiO₂ NRs, the directional transfer, and efficient charge separation at the Au–Ag/TiO₂ Schottky junction, together with the abundant active sites on PS, collectively contribute to the effective degradation of adsorbed CV molecules. Notably, the substrate maintains excellent recyclability and stability even after five consecutive cycles. These findings offer valuable insights for the design of multifunctional SERS platforms for the detection and degradation of organic pollutants.

The rational design of ultrathin Pt-based bimetallic nanostructures with controlled morphology and composition is essential for advancing electrocatalysts for the oxygen reduction reaction (ORR). Alloying Pt with secondary transition metals such as Fe, Co, and Ni is a widely adopted strategy to tune surface chemistry and catalytic behavior; however, achieving controlled incorporation of these metals into ultrathin one-dimensional Pt architecture remains challenging due to disparate reduction kinetics and stringent synthesis conditions. In this work, we present a generalized, template-assisted wet-chemical approach for the synthesis of ultrathin, single-crystalline PtM (M = Fe, Ni, Co) bimetallic nanowires with diameters below 3 nm, using preformed Pt nanowires as structural templates. Stepwise thermal treatment enables controlled incorporation of secondary metals while preserving the one-dimensional morphology and crystallographic coherence of the Pt framework. Comprehensive structural and compositional characterization using X-ray diffraction (XRD), transmission electron microscopy (TEM), high-angle annular dark-field scanning TEM (HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDXS) confirms the formation of high-aspect-ratio bimetallic nanowires with uniform elemental distribution. Electrochemical evaluation toward ORR in alkaline media reveals composition-dependent catalytic behavior, with PtFe nanowires exhibiting the most favorable activity among the studied catalysts. These results highlight the versatility of the template-assisted strategy for producing compositionally tunable Pt-based nanowires and provide insights into the structure–activity relationships governing their electrocatalytic performance.

Graphical abstract

Schematic showing synthesis route of ultrathin PtM (M = Fe, Ni, Co) bimetallic nanowires using Pt nanowire as template.

Gold nanoparticles (GNPs) are currently used in various diagnostic and therapeutic applications due to their biocompatibility and unique optical properties. One of the challenges limiting their use is the sensitivity to the presence of salts, which is manifested in changes of the absorption spectra and the visual color of the sol. In this study, we investigate the physicochemical patterns of complexation at a pH of 7.4 between water-soluble chitosan and ethylene-alt-maleic acid copolymer (EMA), which is used to form a stabilizing shell around gold nanoparticles. It is found that the formation of a polyelectrolyte complex (PEC) does not cause any changes to the spectrum or size of the GNPs. Light scattering and isothermal titration calorimetry methods have shown that at pH 7.4, both carboxyl groups of the EMA unit are successively involved in the complexation process. The changes occurring in the structure of the GNPs’ shell upon the addition of chitosan have been analyzed. Comparison of the effect of salt on the spectral characteristics of GNPs stabilized by an EMA copolymer and those containing PEC in the shell has demonstrated additional stabilization of GNPs against aggregation when PEC is formed. Changes in the absorption spectrum and visual color of the sol containing PEC do not occur until a concentration of 0.15 M NaCl, which makes it promising for increasing the range of its applicability in diagnostic and therapeutic systems in environments with physiological pH and ionic strength.