Small Methods最新文献

In situ monitoring is essential for catalytic process design, offering real-time insights into active structures and reactive intermediates. Electron paramagnetic resonance (EPR) spectroscopy excels at probing geometric and electronic properties of paramagnetic species during reactions. Yet, state-of-the-art liquid-phase EPR methods, like flat cells, require custom resonators, consume large amounts of reagents, and are unsuited for tracking initial kinetics or use with solid catalysts. To overcome these limitations, a droplet-based microfluidics platform is introduced for real-time EPR monitoring of liquid-phase catalytic reactions. By encapsulating solid and dissolved species within nanoliter droplets, this approach enables precise control over mass transport, reduces reagent consumption, and maintains uniform residence times irrespective of acquisition duration, permitting precise analysis of each spectral component under identical conditions. The platform's compatibility with standard resonators facilitates straightforward integration into any EPR spectrometer. Its versatility is demonstrated by monitoring dynamic ligand exchange processes, key for activating homogeneous catalysts, and tracking redox and radical kinetics in ascorbic acid oxidation by Cu(II) catalysts. Importantly, this method captures both supported and dissolved transition metal species, offering comprehensive insights into catalyst deactivation via metal leaching. This microfluidic approach sets a new standard for liquid-phase in situ EPR measurements, advancing studies of homogeneous and heterogeneous catalytic systems.

Photocatalytic transfer hydrogenation of biomass-derived aldehydes to alcohols often results in unwanted coupling co-products. Herein, an ultraselective hydrogen transfer system enabled by in situ oxidative C─C bond cleavage over a Janus single-atom palladium on titanium dioxide (0.5Pd/TiO₂) photocatalyst is presented. The TiO₂ carrier promotes hydrogen-donor activation, while Pd single atoms function as both electron and hydrogen transfer centers, enabling photocatalytic conversion of bio-based furfural to furfuryl alcohol in >99% yield using ethanol as solvent/H-donor at 25 °C. The control/in situ experiments and calculations reveal that ethanol on 0.5Pd/TiO₂ preferentially activates a co-formed coupling by-product to undergo C─C bond cleavage followed by proton-coupled electron transfer, exclusively producing furfuryl alcohol. 0.5Pd/TiO₂ with good reusability is applicable to hydrogenative upgrading of various aldehydes/diols into corresponding monoalcohols with 81‒99% yields. This in situ Janus photocatalytic conversion strategy offers a new approach to eliminate side reactions in reductive upgrading of unsaturated organics/biomass with high selectivity.

Commercial 3D zinc foam anodes with high deposition space and ion permeation have shown great potential in aqueous ion batteries. However, the local accumulated stress from its high-curvature surface exacerbates the Zn dendrite issue, leading to poor reversibility. Herein, we have employed zincophilic N-doped carbon@Sn composites (N-C@Sn) as nano-fillings to effectively release the local stress of high curvature surface of 3D Zn foams toward dendrite-free anode in aqueous zinc ion battery (AZIB). These electronegative and conductive N-C@Sn nano-fillings as supporters can provide a highly zincophilic channel for initial Zn nucleation and reduce local current density for regulating Zn deposition. Uniform Zn deposition further assists homogenous stress distribution on the platting surface, which gives a positive feedback loop to improve anode reversibility. As a result, zinc foam with N-C@Sn composite (ZCSn Foam) symmetric cell achieves a long cycle lifespan of 1100h at 0.5 mA cm^-2, much more than that of Zn Foam (∼80 h lifespan). The full cell ZCSn Foam||MnO₂ exhibits remarkable reversibility with 67% retention after 1000 cycles at 0.8 A g^-1 and 76% after 1600 cycles at 2 Ag^-1. This 3D-constructing strategy may offer a promising and practical pathway for metal anode application.

Flexible perovskite photovoltaic devices are typically constructed on flexible polyethylene naphthalate (PEN) substrates, which exhibit near-ultraviolet absorption and high visible-light reflection, leading to significant optical losses. To address this issue, a reusable optical-management sticker tailored for flexible substrates has been proposed in this work. The sticker incorporates a light-shifting material that converts near-ultraviolet light into visible light, enabling photoelectric conversion of near-ultraviolet light. Additionally, the sticker features a light-trapping microstructure that creates a refractive index gradient from PEN to air, thereby achieving a significant anti-reflection effect. As a result, the efficiency of a flexible perovskite solar cell reached 23.05% (certified 22.46%) under 1 sun AM1.5G illumination and 36.65% (certified 34.03%) under 1000 lux artificial light illumination. Furthermore, scaling this solution to large-area modules has yielded remarkable improvements, achieving a breakthrough certified efficiency of 20.48% (aperture area 21 cm²) in flexible perovskite photovoltaic modules.

Deoxyribonucleic acid (DNA), a fundamental biomacromolecule in living organisms, serves as the carrier of genetic information. Beyond its role in encoding biological functions, DNA's inherent ability to hybridize through base pairing has opened new avenues for its application in biological sciences. This review introduces DNA nanotechnology and DNA-encoded library (DEL), and highlights their shared design principles related to DNA assembly. First, a foundational overview of structural DNA nanotechnology, including its design strategies and historical development is provided. Subsequently, various approaches are examined to dynamic DNA nanotechnology, from strand displacement reactions to DNA-templated polymer synthesis. Second, how the principle of DNA assembly has facilitated the development of diverse formats of self-assembly-based DEL synthesis, DNA-template reactions (DTS), and DNA template-mediated proximity induction effects are examined. These advancements are all underpinned by the unique property of DNA assembly. Finally, this review summarizes the common principles shared by DNA nanotechnology and DEL in terms of methodology and design. Additionally, the potential synergies are explored between these two technologies, envisioning future applications where they can be combined to create more versatile and exquisite functionalities.

The Solid Electrolyte Interphase (SEI) is a nanoscale thickness passivation layer that forms as a product of electrolyte decomposition through a combination of chemical and electrochemical reactions in the cell and evolves over time with charge/discharge cycling. The formation and stability of SEI directly determine the fundamental properties of the battery such as first coulombic efficiency (FCE), energy/power density, storage life, cycle life, and safety. The dynamic nature of SEI along with the presence of spatially inhomogeneous organic and inorganic components in SEI encompassing crystalline, amorphous, and polymeric nature distributed across the electrolyte to the electrolyte-electrode interface, highlights the need for advanced in situ/operando techniques to understand the formation and structure of these materials in creating a stable interface in real-world operating conditions. This perspective discusses the recent developments in interface-sensitive in situ/operando techniques, providing valuable insights and addressing the challenges of understanding the composition/structure/property of SEI and their correlations during the formation processes at spatio-temporal resolution across various length scales.

The nucleophilic reaction between phosphorothioate oligonucleotides and electrophilic reagents has become a cost-effective and efficient approach for oligonucleotide functionalization. This method allows for the precise incorporation of desired chemical structures at specific sites on the phosphorothioate backbone through conjugation with electrophilic groups. The reaction is characterized by its high reactivity and yield, as well as its ability to enhance the hydrophilicity of otherwise hydrophobic compounds. Importantly, this modification preserves the structural and functional integrity of the oligonucleotides, making it a topic of significant interest in nucleic acid research. This article reviews recent advancements in the covalent conjugation of phosphorothioate oligonucleotides with various electrophilic compounds. The article starts with an overview of the mechanisms and general reaction conditions involved in nucleophilic reactions. It then proceeds to examine the distinctive properties and benefits of various electrophilic reagents, offering insights that can inform the rational design of phosphorothioate oligonucleotide functionalization. Finally, the article addresses both the challenges and opportunities in this field, providing perspectives on future theoretical and practical developments to enhance the application of phosphorothioate oligonucleotides in areas like structural analysis, drug develop, drug delivery, fluorescent labeling, and nucleic acid nanotechnology.

Knowledge of the structure-property relationships of functional nanomaterials, including, for example, their size- and composition-dependent photoluminescence (PL) and particle-to-particle variations, is crucial for their design and reproducibility. Herein, the Angstrom-resolution capability of an analytical ultracentrifuge combined with an in-line multiwavelength emission detection system (MWE-AUC) for measuring the sedimentation coefficient-resolved spectrally corrected PL spectra of dispersed nanoparticles is demonstrated. The capabilities of this technique are shown for giant-shell CdSe/CdS quantum dots (g-QDs) with a PL quantum yield (PL QY) close to unity capped with oleic acid and oleylamine ligands. The MWE-AUC PL measurements are calibrated and validated with certified fluorescence standards. The spectrally corrected and size-dependent PL spectra of the g-QDs derived from a single MWE-AUC experiment are then analyzed and compared with the results of single-particle spectroscopic studies, yielding the PL spectra, decay kinetics, and blinking behavior of individual g-QDs. This study underlines the vast potential of MWE-AUC with in-line optical detection for the characterization of advanced nanomaterials with a complex structure.

Exploring potential third-order nonlinear optical (NLO) materials attracts ever-increasing attention. Given that the atomically precise and rich adjustable structural features of silver nanoclusters (Ag NCs), as well as the unique π-electron conjugated system of carbon-based nanomaterials, a supramolecular co-assembly amplification strategy to enhance the luminescent intensity and NLO performance of the hybrids of the two components, are constructed and the relationship between structures and optical properties are investigated. By combining water soluble Ag NCs [(NH₄)₆[Ag₆(mna)₆] (H₂mna = 2-mercaptonicotinic acid, abbreviated to Ag₆─NCs hereafter) containing uncoordinated carboxyl groups with water-soluble fullerene derivatives modified with multiple hydroxyl groups (fullerenols, C₆₀─OH), the π-electron delocalization is expanded owing to non-covalent hydrogen bonding effect between Ag6─NCs and C₆₀─OH, which provides a feasible basis for realizing the NLO response. Then, the co-assemblies are doped into a PMMA matrix to prepare composite film and its NLO properties are evaluated by Z-scan technique. Remarkably, the effective nonlinear absorption coefficients β is of two orders magnitude higher than those of the Ag₆─NCs assemblies at the absence of C₆₀─OH. This work showcases a new approach for amplifying NLO responses which greatly facilitates the development of integrated photonic devices.

Bilayer graphene ribbons (GRs) hold great promise for the fabrication of next-generation nanodevices, thanks to unparalleled electronic properties, especially the tunable bandgap in association with twist angle, ribbon width, edge structure, and interlayer coupling. A common challenge in manufacturing bilayer GRs via templated chemical vapor deposition (CVD) approach is uncontrollable dewetting of micro- and nano-scaled patterned metal substrates. Herein, a confined CVD synthetic strategy of bilayer GR arrays is proposed, by utilizing the bifunctional Ni as a buffered adhesion layer to regulate the anisotropic dewetting of metal film in the V-groove and as a carbon-dissolution regulated metal to initiate the bilayer nucleation. Using C₂H₄ as direct donor of C dimer species, high-quality bilayer GR arrays are synthesized on regular CuNi ribbons with twist angles at 900 °C, harnessing the non-equilibrium jointly induced by confined V-groove and C dimer species. The nucleation and growth mechanism of bilayer GR are investigated with density functional theory (DFT) calculations. The as-grown bilayer GRs display distinctive variable temperature Raman and photoluminescence properties. Our results contribute to a highly controllable technique for fabricating twisted bilayer GR arrays and deep insights into the optical properties of bilayer GRs for potential optoelectronics applications.