ACS Nanoscience Au最新文献

Kinetically controlled morphologies of colloidal magnetic nanoparticles possess unique magnetic properties, making them highly promising for applications in magnetogenetics as magnetic torque probes. Yet, their size-controlled chemical synthesis is in its nascent state. Here, we present a capping-ligand-directed approach to tune the morphology and magnetic properties of Co _x Zn _y Fe_3‑(x+y)O₄ nanoparticles by adding sodium oleate as a cocapping ligand to oleic acid during synthesis, resulting in the formation of monodisperse tetrahedral nanoparticles. Increasing the molar ratio of sodium oleate to oleic acid promotes facet-selective passivation along {111} facets, leading to progressive truncation of tetrahedra and yielding morphologies ranging from truncated tetrahedra to extremely truncated rod-like shapes. Our electron microscopy studies show that the synthesis of tetrahedron-shaped nanoparticles does not require a symmetry-breaking transformation from octahedra, as the initial crystallite formed is tetrahedra. When sodium oleate is removed from the synthesis, thermodynamically driven monodisperse octahedral nanoparticles are formed. We find that ligand composition also influences the doping of ions into the crystal structure, with higher sodium oleate concentrations reducing Zn²⁺ incorporation due to modified metal-ligand coordination. Tetrahedral nanoparticles synthesized under optimal conditions exhibit the highest room temperature saturation magnetization among other morphologies, highlighting their potential for magnetic-nanoparticle-based biosensing applications. Our study underscores that not only morphology but also magnetic characteristics of nanoparticles can be tuned by a ligand-guided chemistry.

The electrification of chemical transformations central to sustainable fuel production and waste valorization, such as overall water splitting (OWS), hydrogen evolution reaction (HER), and electrochemical reduction of CO₂ (CO₂R), presents a powerful opportunity to advance carbon-neutral energy technologies. Transition metal dichalcogenides (TMDs), particularly MoS₂, have emerged as promising electrocatalyst candidates, owing to their abundance, tunable active sites, and defect-rich structures. This review highlights recent progress in leveraging metal doping and heterostructure engineering of MoS₂ to enhance the electrocatalytic activity and selectivity. By compiling insights from experimental studies and density functional theory (DFT) predictions, we examine how defect creation, electronic structure modification, and interface design contribute to improved charge transport and catalytic efficiency. Particular emphasis is placed on rational design principles, synthetic strategies, and operando characterization methods that provide a pathway to understanding and optimizing MoS₂-based materials. We also discuss the challenges of stability, mechanistic ambiguity, and scaling while outlining opportunities to bridge theory and experiment. Collectively, this review underscores how defect and heterostructure engineering of MoS₂ can accelerate the development of efficient, sustainable electrocatalysts for both fuel generation and waste-to-value generation.

In this report, the role that a high-boiling-point solvent type plays on the nucleation and growth, morphology, and crystal-phase transformation of cesium lead bromide nanocrystals (CsPbBr₃) is studied. The CsPbBr₃ products were compared between a one-pot growth mechanism at room temperature (RT) versus a hot-injection mechanism (HI) control using dibenzyl ether (DBE), diphenyl ether (DPE), dioctyl ether (DOE), or 1-octadecene (ODE). The coordination between these solvents and the PbBr₂ salt precursors resulted in different plumbate [PbSBr _n ]^2-n precursors being formed. The S-to-Pb²⁺ coordination within [PbSBr _n ]^2-n was probed by UV-vis and solvent-phase ²⁰⁷Pb NMR, both of which showed considerable coordination between [PbSBr _n ]^2-n and the π-rich DBE and DPE, whose reactivity affected CsPbBr₃ growth. The effect was more pronounced for CsPbBr₃ prepared via RT, where the morphology was tunable, with π-rich solvents producing thin rod-like CsPbBr₃ with a blue emission, compared to the green-emitting thicker platelets formed via HI. While XRD showed crystalline products for both RT and HI, with orthorhombic and cubic forms, respectively, the RT products had considerable surface defects, as was indicated by lower quantum yields, and to understand this the photoluminescent lifetimes were measured by time-correlated single photon counting.

We demonstrate that the etching chemistry used during MXene synthesis from Ti₃AlC₂ MAX phase significantly influences surface functionalization and structural vacancies, which in turn affect ruthenium (Ru) ion interactions. Using hydrofluoric acid (HF) and ammonium bifluoride (NH₄HF₂) as etchants, we obtained MXene surfaces with distinct functional groups and Ti vacancies that impact Ru ion interactions and electrochemical performance. Both MXene variants (labeled MX-(H) and MX-(N), respectively) exhibited negative zeta potentials in their pristine state, but upon the addition of Ru the zeta potential for MX-(H) reached 12.9 mV while that for MX-(N) remained negative at -6.4 mV. This adsorption resulted in a 14.4-fold increase in the specific capacitance of MX-(H)/Ru compared to pristine MX-(H), whereas MX-(N)/Ru exhibited only a 4.4-fold increase over its pristine counterpart. X-ray diffraction analysis identified the formation of ammonium titanium oxide fluoride, (NH₄)₃TiOF₅, on MX-(N), which likely contributed to its reduced Ru adsorption. X-ray photoelectron spectroscopy suggested the presence of Ti vacancies in both MXene variants; however, their behavior toward Ru accommodation differed markedly, with MX-(H) showing the most obvious shift in the Ti 2p peak in the XPS survey spectrum, while MX-(N) showed the most obvious shift in the C 1s peak. Electron paramagnetic resonance spectroscopy further demonstrated a distinct alteration in the spectral signatures of MX-(H) upon Ru addition, in contrast to the negligible changes in MX-(N), indicating effective passivation of the Ti defect sites in MX-(H) via vacancy-assisted Ru doping. Cyclic voltammetry showed that Ru-incorporated MX-(H) nanocomposites exhibit more efficient redox-active sites, as reflected in their higher capacitance values. These findings highlight the pivotal role of MXene surface chemistry in controlling cation adsorption, providing valuable insights for the rational design of high-performance electrodes.

Quantum phase slips (QPSs) have emerged as a key mechanism driving the breakdown of superconductivity in one-dimensional (1D) systems, especially under strong quantum fluctuations and disorder. In this context, we report the observation of a quantum phase slip event in quasi-1D Nb₂PdS₅ nanowires. Our findings reveal that as the wire width is reduced below the magnetic penetration depth, the superconducting transition (T _c) broadens significantly, a behavior that aligns well with the QPS theoretical model. The temperature-dependent resistance under magnetic fields applied perpendicular and parallel to the applied current (b-axis) of the Nb₂PdS₅ nanowire device shows the highest upper critical field (B _c2) at around 73.3 T for B//I. The upper critical field B _c2 exhibits strong anisotropy and exceeds the Pauli limit (B _p ^BCS ≈ 11.96 T) under parallel magnetic fields, which is consistent with the enhanced role of QPSs. Current-voltage (I-V) characteristics reveal discrete voltage steps during the superconducting transition to the normal state, further confirming the occurrence of the QPS event in the quasi-1D superconducting system. The reduction in critical current I _c with decreasing wire width provides an experimental signature of the QPS.

Dual plasmonic heterostructures composed of gold nanoparticles (Au NPs) and nonstoichiometric copper chalcogenides (Cu_2‑xE) have garnered attention for their unique electronic interactions between two intrinsically dissimilar constituent domains. However, the site-selective deposition of Cu_2‑xE on Au NPs remains extremely challenging due to the difficulty in controlling nucleation and regioselective overgrowth. Herein, we propose a universal Selenide (Se)-mediated approach for precise spatial control of Cu_2‑xSe on gold nano bipyramids (Au NBPs). By deliberately tuning the surfactant environment, Cu_2‑xSe can be selectively deposited on one waist, both lateral sides, and tips of Au NBPs to form UFO-like, segregated islands, and spindle-like morphologies, respectively. Furthermore, the domain size of the Cu_2‑xSe and the plasmonic properties of Au@Cu_2‑xSe can be controlled by adjusting the amount of selenium (SeO₂) precursor. This work establishes a new strategy for the rational design and fabrication of multicomponent functional nanoarchitectures with precisely controlled compositions and tailored plasmonic properties, thereby expanding their scope of applications.

This study examines the detection of oligonucleotide-specific signals in sensitive optomechanical experiments. Silica nanoparticles were functionalized using ZnCl₂ and 25-mers of single-stranded deoxyadenosine and deoxythymidine monophosphate which were optically trapped by a 1550 nm wavelength laser in vacuum. In the optical trap, silica nanoparticles behave as harmonic oscillators, and their oscillation frequency and amplitude can be precisely detected by optical interferometry. The data was compared across particle types, revealing differences in frequency, width, and amplitude of peaks with respect to motion of the silica nanoparticles which can be explained by a theoretical model. Data obtained from this platform was analyzed by fitting Lorentzian curves to the spectra. Dimensionality reduction detected differences between the functionalized and nonfunctionalized silica nanoparticles. Random forest modeling provided further evidence that the fitted data were different between the groups. Transmission electron microscopy was carried out but did not reveal any visual differences between the particle types.

Autonomous experiments (AEs) are transforming how scientific research is conducted by integrating artificial intelligence with automated experimental platforms. Current AEs primarily focus on the optimization of a predefined target; while accelerating this goal, such an approach limits the discovery of unexpected or unknown physical phenomena. Here, we introduce a novel framework, INS²ANE (Integrated Novelty Score-Strategic Autonomous Non-Smooth Exploration), to enhance the discovery of novel phenomena in autonomous microscopy experimentation. Our method integrates two key components: (1) a novelty scoring system that evaluates the uniqueness of experimental results and (2) a strategic sampling mechanism that promotes exploration of under-sampled regions even if they appear less promising by conventional criteria. We validate this approach on a preacquired data set with a known ground truth comprising of image-spectral pairs. We further implement the process on autonomous scanning probe microscopy experiments. INS²ANE significantly increases the diversity of explored phenomena in comparison to conventional optimization routines, enhancing the likelihood of discovering previously unobserved phenomena. These results demonstrate the potential for autonomous microscopy experiments to enhance the scientific discovery by navigating complex experimental spaces to uncover novel phenomena.

We resort to first-principles molecular dynamics (FPMD) and density functional theory (DFT) calculations at the PBE and PBE0 levels of theory to examine the structure, stability, and electronic properties of zirconia nanoparticles (NPs) with diameters ranging from 0.9 to 2.0 nm. A procedure based on the use of water molecules and an appropriate MD thermal annealing cycle is developed to generate [ZrO₂] _n models with different sizes (n = 14, 16, 43, 80, and 141) and different surface passivation states. It is shown that the rate of passivation has a significant influence on the NP structure and that NP models corresponding to saturated passivation exhibit the best structural characteristics, featuring close agreement with experimental atomic pair distribution functions (PDFs). It is also found that the Zr-O bond length varies as a function of the position of Zr and O atoms from the core to the surface of NPs, providing a descriptor capable of separating core and surface regions in ZrO₂ NPs. A core-shell structure has been demonstrated for NP models as small as 1.3 nm, while for even smaller NPs, no separation between the core and shell is possible. For the largest NP models, the core atoms show local environments closer to the cubic phase of zirconia, while the local structure of atoms close to the surface shows a large similarity with the monoclinic phase. Finally, the study of electronic properties has shown that ZrO₂ NPs exhibit very moderate quantum confinement effects. Moreover, the evolution of the band gap as a function of size does not correspond well with the d ^-2 trend expected from the effective mass approximation model. These differences can only be partly attributed to the shell atoms, which induce a slight decrease in the band gap compared to the contribution of the core atoms.

Plasmonics is a rapidly growing field of research based on plasmonic nanostructures. To exploit the full potential of this fascinating class of materials, it is indispensable to tune and optimize the properties of these structures, which requires precise knowledge and optimization of their synthesis processes. Plasmonic silver nanocubes for applications in nonpolar media are obtained by an AgCl-mediated hot-injection method. In this process, catalysis by Fe species is of central importance, as the Fe species influence the reaction in multiple ways, enabling a finely balanced control of the nanocube synthesis. Using electron microscopy, optical spectroscopy, and X-ray photoelectron spectroscopy, it is shown that the Fe species not only direct the reaction of the Ag precursor to the formation of AgCl nanoparticles instead of icosahedral Ag nanoparticles but also enhance the reduction rate of AgCl, from which the Ag nanocubes are formed and grow. Based on these results, a detailed reaction mechanism is proposed. An additional comparison of the effects of different metal ions on the reaction shows that iron ions are highly likely to be specific as catalysts for this synthesis. The results also indicate that the Fe ions are likely present in the form of an organic iron complex, catalyzing the chloride transfer.