Small Methods最新文献

Microscale patterning of delicate materials such as colloidal nanoparticle monolayers, solvent-swollen polymer substrates, and 3D resonators in millimeter/terahertz (mm/THz) dielectric metasurface remains a formidable challenge for conventional photolithography. Overcoming these limitations is critical for the next generation of wearable electronics, photonic devices, and metamaterials. Here, a versatile strategy using photocurable perfluoropolyether (PFPE) is introduced to create high-precision, reusable soft template guided by predesigned photomasks. These templates enable non-destructive, high-fidelity transfer of diverse functional materials including metal films, composites, and nanoparticle monolayer onto a wide range of substrates. Remarkably, the PFPE template can be reused multiple times without compromising patterning fidelity, offering a cost-effective solution for large-scale manufacturing. Beyond general microscale patterning, this approach provides unprecedented control over 3D dielectric resonators in mm/THz all-dielectric metasurfaces, delivering superior electromagnetic performance. With its combination of precision, reusability, and adaptability to various surfaces, this method opens exciting opportunities for microscale fabrications across flexible electronics, advanced photonics, and metasurfaces, redefining what is possible with soft-template patterning.

The Sb₂S₃ absorber has received tremendous attention in recent years for high-performance solar cells due to its excellent optoelectronic properties, especially for indoor photovoltaics that have gained significant interest as a sustainable solution for powering Internet of Things electronics. However, the Sb₂S₃ absorber suffers from its complicated defect characteristic, which is closely associated with the quasi-1D crystal structure. Herein, a chemical bath deposition (CBD) based precursor engineering strategy is developed to deposit high-quality Sb₂S₃ absorber films via pH regulation and nominal cation doping. The careful characterization of Sb₂S₃ films reveals that the manipulation of the chemical environment of CBD precursor solutions promotes the heterogeneous nucleation and growth of Sb₂S₃ films on the substrate, further resulting in the reduction in the grain boundary (GB) density. The reduced GB contributes to the decrease in defect density in Sb₂S₃ films. Benefitting from the suppressed nonradiative recombination and increased carrier concentration, the resultant planar Sb₂S₃ solar cells yield a competitive power conversion efficiency of 7.90%. Furthermore, a high-performance Sb₂S₃ solar minimodule with an active area of 16.25 cm² is first constructed using laser scribing. This work underscores the importance of the precursor engineering for solution-processed antimony chalcogenide solar cells.

The evaluation of the oxygen evolution reaction (OER) electrocatalytic activity of established electrocatalysts is key for the rational design of new electrocatalysts. In this study, scanning electrochemical cell microscopy (SECCM) is employed to assess, under identical conditions, the OER electrocatalytic activity of Ni₂B and Ni₃B, simultaneously present in a Ni₇₀B₃₀ ingot. An important finding is that the gas environment surrounding the nanodroplet formed at the tip of the SECCM probe and the Ni₇₀B₃₀ ingot impacts the measured current density. The presence of a gas flowing (air, Ar, CO₂, and O₂) outside the electrolyte droplet increases the measured OER current recorded on both phases, compared to a situation without gas convection, revealing one of the key parameters that can be used to enable higher OER current densities to be recorded on the same catalyst. Notably, the presence of CO₂, even in small concentrations (2% O₂ in Ar) in the surrounding atmosphere, leads to a significant apparent decrease of the OER activity. The study reveals that Ni₃B shows an almost 20% enhanced OER electrocatalytic activity compared to Ni₂B, which contradicts previous findings and highlights the importance of precisely controlled experiments enabled by SECCM when establishing catalytic trends.

The combination of structural DNA nanotechnology and lithographic surface patterning has recently advanced from proof-of-principle demonstrations to device-relevant applications, including field-effect transistors, prototypical photodiodes, plasmonic metasurfaces, quantum light sources, dynamic nanomachines, and single-molecule sensor arrays where molecular devices are patterned on the sub-micrometer scale. Recent advances now allow the deterministic placement of DNA nanostructures of varying geometries, sizes, and complexities onto chip surfaces, as well as subsequent on-surface assembly into hierarchical architectures. In this review, we summarize fabrication strategies for DNA self-assembly on lithographically patterned substrates, focusing on two main areas: (i) methods for designing and depositing DNA nanostructures and enabling surface self-assembly, and (ii) techniques for fabricating patterned surfaces through lithography and chemical functionalization. We then highlight advances across optoelectronics, quantum technologies, and biotechnology, identify key remaining challenges, and conclude with a perspective on how the combination of DNA nanotechnology and lithography may provide a foundation for next-generation nanoscale devices.

This study introduces the direct growth of WO₃ and W₁₈O₄₉ nanowires on patterned fluorine-doped tin oxide (FTO) by a hydrothermal technique, obviating the necessity for traditional interdigitated electrode designs based on Pt, Ag, Au, or Cu. The resulting W₁₈O₄₉ nanowires network exhibits a distinctive interconnected morphology with an average diameter of 11 ± 1.80 nm that is reminiscent of clusters with structural linkages, thereby augmenting both surface area and electronic pathways. This architecture facilitates the selective detection of NO₂ gas with a significantly superior response value of ≈152 at 100 °C, in contrast to WO₃ nanowires, which exhibit a response of ≈110 under identical conditions. The W₁₈O₄₉ nanowires network further demonstrates quick response and recovery times of 9 and 20 s, respectively, compared to the WO₃ nanowires network, which has 24 and 31 s, respectively. Comparative analysis with WO₃ nanowires synthesized with and without the support of FTO scaffold underscores the advantages of this configuration. In contrast to powdered forms that generate nanowires without interconnectedness, direct growth on FTO results in a robustly networked nanowire structure crucial for enhanced gas sensing performance. These results establish W₁₈O₄₉ nanowires on patterned FTO as a prospective architecture for the high-performance, selective detection of NO₂.

Developed an efficient bifunctional electrocatalyst for alkaline and seawater environments, crucial for sustainable hydrogen production. In this study, Ru/P dual-doped self-supported cobalt molybdate (Ru/P-CoMoO₄) nanorod array catalysts with large surface areas and abundant catalytic sites are synthesized. Additionally, Ru/P co-doping optimizes the electronic structure to facilitate electron transfer and enhance reaction kinetics. Density-functional theory calculations reveal this modulation also optimizes H* adsorption and confers Cl⁻ poisoning resistance, resulting in superior hydrogen evolution reaction (HER)/oxygen evolution reaction (OER) performance in alkaline freshwater and seawater. Consequently, the self-supported Ru/P-CoMoO₄ electrode delivers exceptional HER performance (η₁₀ = 29 mV, η₁₀₀₀ = 231 mV), OER performance (η₁₀₀ = 308 mV, η₅₀₀ = 399 mV). The catalyst also shows outstanding overall water splitting (OWS) performance, requiring only 1.535 V in alkaline media and 1.581 V in alkaline seawater to achieve a current density of 10 mA cm⁻², with excellent long-term durability of 200 h at 100 mA cm⁻². This work effectively deploys sustainable green-hydrogen systems powered by wind and solar energy, offering a viable strategy for future large-scale sustainable hydrogen production.

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.

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.

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.