Small Methods最新文献

Scanning electrochemical cell microscopy (SECCM) is a versatile tool for localized electrochemical mapping, material modification, and microfabrication. In its hopping mode, the pipette-based system confines reactions to the meniscus contact area, allowing precise deposition control. Here, an SECCM-driven strategy for polypyrrole (PPy) microfabrication using phosphate buffer as the electrolyte, combined with an intermediate cleaning step to remove side products and prevent pipette clogging, is reported. This approach enables the production of uniform, circular PPy deposits with high reproducibility on gold substrates. A multi-microscopy "conveyor-belt" analysis - combining SEM, AFM, EDX, and Raman spectroscopy - reveals that phosphate ions intercalate into the PPy matrix during polymerization, as also seen in bulk studies. This intercalation is found to be reversible via post-deposition rinsing. Furthermore, this work demonstrates that cyclic voltammetry-based deposition enables patterned PPy growth on complex surfaces such as boron-doped carbon nanowalls, overcoming surface charge and wetting challenges. These findings expand the applicability of SECCM for 2D conducting polymer micro-/nanofabrication on both flat and structurally complex substrates.

3D printing via direct ink writing (DIW) enables the precise fabrication of macroscale architectures for high-performance electromagnetic wave absorption elastomers (EMWAEs). However, achieving inks that combine excellent printability with superior electromagnetic and mechanical properties remains challenging. Here, a scalable fabrication strategy employing MXene@modified-RGO@SiO₂ microspheres synthesized through continuous spheroidization is presented. The incorporation of SiO₂ nanoparticles on the microsphere surface preserves the spherical morphology, enhances dispersion within the silicone elastomer matrix, and optimizes rheological behavior for stable DIW extrusion. Guided by electromagnetic simulations, three-layer gradient-porous structures is designed and printed that maximize interfacial polarization and multiple scattering effects. The resulting elastomers exhibit a minimum reflection loss (RL_min) of -44 dB and a maximum effective absorption bandwidth of 7.2 GHz at a thickness of only 3 mm. In addition to their outstanding electromagnetic performance, the printed materials demonstrate improved thermal conductivity and tensile strength, offering a multifunctional platform suitable for flexible and wearable electronic devices. This approach provides a simple, effective, and customizable route for integrating advanced fillers into 3D-printable elastomers, paving the way for next-generation EMWAEs with tunable architectures, broad bandwidth absorption, and mechanical robustness.

Nano-lignocellulose exhibits great potential for high-value utilization due to its large specific surface area and excellent dispersibility. However, conventional fabrication methods typically rely on chemical reagents, leading to inevitable environmental concerns. Here, a dry processing method for the fabrication of nano-lignocellulose powder is proposed. A mechanical pulverization device based on electromagnetic acceleration is designed, in which multiple coils are sequentially energized to generate magnetic fields, driving magnetic microparticles into high-speed motion. These high-speed magnetic particles collide with lignocellulose and induce its fragmentation, thus enabling the nanoscale fabrication of lignocellulose. Compared with conventional shear-based mechanical pulverization methods, this electromagnetic approach achieves significantly finer particle sizes. Scanning electron microscopy reveals particle sizes of ≈300-400 nm, while Brunauer-Emmett-Teller analysis indicates a 177.2% increase in specific surface area. The absence of solvents ensures retention of the native chemical components. The magnetic fragmentation does not disrupt the lattice, and the original crystalline structure and thermal stability remain unchanged. Mechanical testing of modified biomass composites demonstrates that tensile strength increases with decreasing lignocellulosic particle size. Incorporation of nano-lignocellulose results in a remarkable 72% enhancement in tensile strength compared to neat polylactic acid.

Since the discovery of graphene, control of its carrier density via doping or functionalization has been a crucial need. Despite significant progress, precise control of the carrier density for epitaxial graphene on SiC remains a challenge. Multiple cycles of doping and characterization are often required before achieving a desired carrier density. In this work, a new approach is demonstrated to precisely program the doping level in top-gated epitaxial graphene devices that are exposed to nitric acid vapor before the gate deposition. With the help of an applied gate voltage, the modification of carrier concentration introduced by the nitric acid can be reversibly controlled, while the corresponding carrier density at zero gate voltage can be accurately tuned by more than 4 × 10¹³ cm^-2 across the charge neutrality point. This gate-assisted molecular doping enables tuning of the charge neutrality point to the desired gate voltage value and can be stabilized by cooling the sample below 200 K.

Strengthening delocalized singlet exciton (DSE) is an effective strategy to improve open-circuit voltage (V_oc) and short-circuit current density (J_sc) in organic solar cells (OSCs); however, practical methods to achieve this are still severely limited. In this work, the novel guest acceptor J-OC is introduced to modulate DSE formation as well as bulk heterojunction morphology within the PM6:BTP-eC9 host system. J-OC's low nucleation barrier enables it to act as a seed crystal, effectively accelerating nucleation and optimizing crystallization kinetics. This process significantly enhances crystallinity and crystal perfection, facilitating DSE formation and contributing to improved V_oc. Furthermore, GIWAXS and morphology analyses reveal J-OC's multifunctional role in enhancing component miscibility, optimizing exciton distribution, and promoting a fiber-like morphology. Consequently, ternary devices based on PM6:BTP-eC9:J-OC achieved an outstanding power conversion efficiency (PCE) of 20.02%, with simultaneous increases in V_oc, J_sc, and fill factor. This performance surpasses binary devices based on PM6:BTP-eC9 (PCE = 19.08%) and PM6:J-OC (PCE = 17.05%). This work demonstrates the synergistic effects of employing a low-nucleation-barrier guest acceptor in a ternary strategy to concurrently optimize DSE formation and morphology.

Understanding and establishing the relationship between the defect and macroscopic characteristics is crucial for materials. It is great challenge for linking atomic-scale defect structures to device performance owing to the difficulty in isolating single-type defects in a material. In this work, single-crystal and twin-structured GaN nanowires are prepared, and the performance of photodetectors based on two types of nanowires differs by two order of magnitude. Through analysis of the microstructure at the atomic scale, it is revealed that this difference in performance is due to the presence of unique disconnection structure in the twin nanowires. The embedded dual stacking faults at the disconnection position will introduce stacking mismatch boundaries in the crystal. Combining density functional theory calculations, it is revealed that the stacking mismatch boundary generates deep defect states in the band structure, which explains the performance degradation caused by the { $10\overline{1}3$ } twin boundary.

Spatial transcriptomics has transformed the understanding of gene regulation by enabling high-resolution mapping of RNA molecules within their native cellular and tissue environments. This is typically accomplished by capturing or imaging RNA in situ, thereby preserving spatial context. Here, an in situ RNA imaging method based on split-probe ligation and rolling circle amplification (RCA) for profiling spatial gene expression is introduced. In this approach, split-probes hybridize to adjacent regions of a target RNA fragment and are then enzymatically ligated to form circular DNA templates, which are subsequently amplified via RCA to boost the signal. It is demonstrated that this method enables robust in situ RNA detection and genotyping in both tissue sections and whole-mount tissue samples. By coupling this technique with in situ sequencing, the spatial expression patterns of 82 genes in the kidneys of healthy and diabetic male and female mice are mapped. This analysis reveals distinct localization of Aqp4 in proximal tubules and principal cells of the collecting ducts, and uncovers sex-specific transcriptomic alterations in diabetic kidneys with spatial resolution.

The formation of lithium dendrites and dead lithium during deposition/stripping process restricts battery performance especially in wide temperature range. However, due to the lack of real-time detection methods, the intrinsic mechanism of how operational temperature affects the dynamic process on lithium metal anodes is still unclear. Here, an in situ investigation of lithium deposition and dead lithium formation during the first charge-discharge cycle in an ether-based electrolyte system is presented. Both the deposition process and stripping process are found to be temperature dependent. Below 293 K, the lithium deposition is less dense plating and the dead lithium is formed, which contributes to the capacity loss. Above 293 K, the lithium deposition becomes denser, and dead lithium formation is significantly reduced. The capacity loss is primarily driven by the formation of solid electrolyte interphase (SEI) resulting from reactions between lithium and ether-based electrolyte. Further study reveals that the ratio of lithium oligoethoxides on the SEI changes abruptly with temperature above 293 K and thus significantly alters the conductivity and reactivity of SEI, which leads to the abrupt change of the deposition/stripping process. These findings highlight the critical role of temperature in lithium deposition/stripping processes in ether-based anode-free lithium metal batteries.

Solid polymer electrolytes (SPEs) offer flexibility and processability but suffer from low ionic conductivity and inadequate mechanical strength. Here, a facile, solvent-free electron beam (EB) irradiation method is introduced to modify poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PDADMATFSI)-based SPEs for lithium metal batteries. At an optimal dose, EB irradiation simultaneously generates polar carbonyl groups and induces a crosslinked network. The carbonyl groups facilitate lithium-ion transport and contribute to forming a robust, Li₂O-rich solid electrolyte interphase. Concurrently, the crosslinked architecture enhances mechanical integrity and suppresses the growth of lithium dendrites. As a result, Young's modulus increases from 170 to 921 MPa, ionic conductivity rises from 4.7 × 10^-4 to 8.2 × 10^-4 S cm^-1, the lithium-ion transference number (t_Li ⁺) improves from 0.29 to 0.48, and the dielectric constant increases from 6.5 to 16.6. Consequently, Li||Li symmetric cells with modified SPE cycle stably for 2000 h (0.05 mA cm^-2), 600 h (0.1 mA cm^-2), and 180 h (0.2 mA cm^-2), with a critical current density of 1.1 mA cm^-2. Li||NCM811 (LiNi_0.8Co_0.1Mn_0.1O₂) full cells deliver 83.7% capacity retention after 300 cycles at 1C and superior rate performance. This work demonstrates that EB irradiation is a promising and effective strategy for developing high-performance solid-state lithium metal batteries.

Molybdenum disulfide (MoS₂) has attracted a wide range of research attention due to its distinct electronic structures and the great potential for use in emerging microelectronic and photonic devices. However, the development of MoS₂-based micro-electronic/photonic devices lags far behind expectations mainly because of the lack of efficient microfabrication technology. Here, a high-resolution precision photoreduction technology is presented for directly printing MoS₂ micropatterns that can be decorated into gold nanoparticle (AuNP)/ MoS₂ heterostructure for ultrasensitive surface-enhanced Raman spectroscopy (SERS) sensing. Micropatterns of MoS_x nanoparticles are initially grown toward a target size in a light-controlled manner and then transformed into a micropatterned pure MoS₂ nanofilm through thermal annealing. Thereafter, size and gap-controlled AuNPs are grown selectively on the surface of MoS₂ to form a self-aligned AuNP/MoS₂ heterostructure with desired optical properties. Thanks to both electromagnetic and chemical enhancements, the directly printed plasmonic AuNP/ MoS₂ substrate can greatly enhance Raman signals to detect crystal violet (CV) and 4-mercaptobenzoic acid (4-MBA) at 10^-12 m under the excitation of 785-nm laser. This multiscale-engineered plasmonic AuNP/MoS₂ substrate is rapidly printed without relying on expensive and time-consuming nanofabrication processes, offering a new technical approach for future development of MoS₂-based micro-devices and sensing platforms.