Small Methods最新文献

Self-assemble monolayers (SAMs) have become state-of-the-art hole-selective contacts for high-efficiency perovskite-based solar cells due to their easy processing, passivation capability, and low parasitic absorption. Nevertheless, for the deposition of SAMs with a monolayer thickness and a high packing density on metal oxide substrates, critical challenges persist. To overcome these, the study focuses on the impact of annealing temperature - an intrinsic yet so far unexplored process parameter - during the formation of SAMs. By performing in situ angle-resolved X-ray photoelectron spectroscopy combined with advanced data analysis routines, it is revealed that increasing the annealing temperature reduces the formed SAM layer thickness from a multilayer stack of ≈5 nm at 100 °C (conventional temperature employed in literature) to a monolayer at 150 °C. Furthermore, denser adsorption of the SAM to the metal oxide surface is promoted at high temperatures, which enhances the interfacial SAM/perovskite passivation quality. With this strategy, a 1.3%_abs power conversion efficiency (PCE) increment is obtained in fully-textured perovskite/silicon tandem solar cells, with improved reproducibility, and a champion device approaching 30% PCE. This study advances the understanding of SAMs formation and presents a promising strategy for further progress in high-efficiency perovskite-based solar cells.

Silver nanostructures are highly valued in nanophotonic devices due to their appealing plasmonic properties and affordability relative to gold. Yet, fabricating high-quality, monocrystalline silver nanostructures, with full control over the shape, is challenging. A mild, liquid-phase method for the epitaxial welding of adjacent monocrystalline silver nanocubes in reductant-free conditions is introduced to prevent the formation of detrimental nuclei on the surface that can degrade the nanostructures' optical qualities. The mechanism is thoroughly investigated and it is found that the nanocubes themselves can act as reducing agents, promoting growth preferentially into the gap as a result of electrostatic interactions. By controlling experimental parameters such as temperature, pH, and the introduction of capping agents, a balance between nanocube epitaxy and shape retention is achieved. Finally, by applying this procedure to nanoparticle assembled in predefined meta-atoms, the feasibility of creating intricate silver nanostructures, that are monocrystalline as verified by transmission electron microscopy (TEM), is demonstrated. This advancement paves the way for bottom-up fabrication of optical metasurfaces that can be swiftly integrated in devices.

Single-molecule fluorescence techniques provide exceptional sensitivity to probe biomolecular interactions. However, their application to accurately quantify analytes at the picomolar concentrations relevant for biosensing remains challenged by a severe degradation in the signal-to-background ratio. This so-called "low concentration barrier" is a major factor hindering the broad application of single-molecule fluorescence to biosensing. Here, the low concentration limit is broken into while keeping intact the confocal microscope architecture and without requiring complex microfluidics or preconcentration stages. Using fluorescence lifetime correlation spectroscopy (FLCS) and adding a diaphragm to the laser excitation beam, a limit of quantitation (LOQ) down to 0.1 pM is achieved, significantly below the state-of-the-art. The physical parameters setting the LOQ and introduce a broadly applicable figure of merit (FoM) is identified that determines the LOQ and allows for a clear comparison between experimental configurations. The approach preserves the ability to monitor dynamic interactions, and diffusion times, and distinguish species in complex mixtures. This feature is illustrated by measuring the biotin-streptavidin association rate constant which is highly challenging to assess quantitatively due to the strong affinity of the biotin-streptavidin interaction. These findings push the boundaries of single-molecule fluorescence detection for biosensing applications at sub-picomolar concentrations with high accuracy and simplified systems.

Milk-derived extracellular vesicles (mEVs) are promising therapeutic delivery platforms due to their natural bioactivity, biocompatibility, and ability to cross biological barriers. However, analyzing their cellular uptake and trafficking is limited by existing fluorescent labeling methods, which often cause dye leakage and disrupt vesicle integrity. Here, a glycan-anchored fluorescence labeling strategy for mEVs is developed, involving periodate oxidation of surface sialic acids followed by aniline-catalyzed ligation of hydrazide-functionalized fluorophores. Nano-flow cytometry characterization confirmed ≈100% labeling efficiency without compromising mEVs integrity or uptake behavior. This approach enabled quantitative analysis of mEVs internalization, identifying clathrin-mediated endocytosis and macropinocytosis as the primary pathways and confirming mEVs' capacity for lysosomal escape. Comparative analyses showed that traditional lipophilic dyes induced vesicle aggregation, dye leakage, and transfer, potentially misrepresenting mEVs behavior. Additionally, co-labeling mEVs with glycan-anchored fluorophores and FITC-conjugated paclitaxel enabled real-time tracking of drug delivery, revealing a burst release from lysosomes that led to significant cytotoxicity. Overall, the glycan-anchored fluorescence labeling allows precise analysis of mEVs uptake and intracellular fate, paving the way for further research and application in targeted drug delivery.

Metal halide perovskite solar cells (PSCs) are emerging as promising candidates for next-generation photovoltaics aimed at green energy production. However, during solution-processed film deposition, the distinct rheological behaviors of blade coating, compared to spin coating, result in less controlled crystallization, leading to inferior film quality and limiting the power conversion efficiency (PCE) of blade-coated photovoltaics. In this work, ethylene glycol (EG) is introduced as an inert co-solvent in perovskite precursor solutions to achieve high-quality perovskite films via blade coating. The high viscosity of EG facilitates the deposition of thick perovskite films ranging from 400 to 2000 nm, while its low vapor pressure effectively suppresses premature nucleation before vacuum flashing, leading to films with enhanced morphology. As a result, the blade-coated PSCs achieve an impressive champion PCE of 24.10% and retain 89% of their initial efficiency after 600 h of continuous operation.

Developing high-performance electrodes derived from cellulosic wastes is an effective strategy for promoting large-scale energy storage and achieving carbon neutrality, yet how to enhance capacitive activity from the perspective of surface-interface structure regulation remains a challenge. Herein, a disulfide bond reinforced self-assembly of cellulosic wastes strategy is demostrated to fabricate 3D carbon foams with thiram and bio-straws as examples. The cellulose-enriched piths of straws (EP) are impregnated with thiram solution followed by pyrolysis, where thiram can form a stable 3D cross-linked networks via disulfide-centered hydrogen bonds reinforced self-assembly of EP and thiram, endowing the obtained starfish-like skeleton connected 3D carbon foams with high N/S contents and hierarchical porous structure. Consequently, The resultant EPCF-800 as a binder-free and conductive agent-free electrode achieves an ultrahigh specific capacitance of 342 F g^-1 in aqueous electrolyte at 0.5 A g^-1, meanwhile, DFT calculations reveal that the high-level N/S-doping can effectively weaken the adsorption barriers of K-ions. Moreover, the EPCF-800 assembles flexible solid-state supercapacitors delivering a high energy density of 30.11 Wh kg^-1 and a long cycle-life. This work will shed light on the value-added utilization of cellulosic wastes from surface-interface engineering and molecular chemical engineering to pave the way for fabricating high-performance supercapacitors.

With their low density and high porosity, aerogels are widely used as supporting frameworks for phase change materials (PCMs). However, the host-guest solid-liquid phase-change systems often encounter difficulties in optimizing the balance between mechanical properties and thermal energy storage performance, the intrinsic advantages of aerogels not being fully realized. Herein, an aerogel-functionalization-PCM strategy, a completely converse route compared to traditional aerogel-filling-PCM method, toward lightweight, flexible PCM for robust thermal management is developed. As a proof of concept, silica aerogel particles (SAPs) as functional components are added to a polyvinyl alcohol-polyethylene glycol network to produce composite PCMs. The addition of SAP reduces the composite PCM's latent heat by 25% but significantly decreases the heating rate by 190% and enhances thermal insulation by 147%, achieving a 28 °C temperature drop at 80 °C. This work provides a fresh perspective on the design of flexible and thermally robust PCMs and demonstrates the feasibility of enhancing thermal protection under reduced latent heat conditions.

Impacting droplets on hot solid surfaces is a widely used method for thermal management across various applications. Efficient heat transfer relies on the rapid detachment and directional shedding of these impacting droplets. Additionally, suppressing the Leidenfrost effect is crucial. However, there are currently no engineered surfaces that can simultaneously achieve reduced contact time, directional droplet shedding, and Leidenfrost suppression at high temperatures. This work introduces a novel type of surface with asymmetric re-entrant microgrooves (ARG surfaces) to address this challenge. ARG surfaces demonstrate Leidenfrost points (LFPs) as high as 725 °C and contact times lower than the theoretical limit at temperatures ranging from 350 to 650 °C. Additionally, they exhibit superior droplet centroid velocities and non-dimensional displacement factors. A theoretical model is also developed to predict the LFPs of these surfaces. Furthermore, temperature profiles of plain Si and ARG surfaces upon droplet impact confirm the superior cooling performance of ARG surfaces compared to plain Si. These results highlight the potential of ARG surfaces for achieving efficient cooling in diverse high-temperature applications.

Photodegradation

In article number 2301541, Vomiero, Moretti, Polo, and co-workers set up a new synthetic protocol to obtain nickel hexacyanoferrate (Ni-HCF) nanocubes as suitable photocatalysts toward organic contaminants in water. Ni-HCF nanocubes were tested to remove metronidazole (MDZ), a water contaminant antibiotic. Under simulated solar light, Ni-HCF display substantial photocatalytic activity, degrading 94.3% of MDZ in 6 hours. These achievements highlight the possibility to combine the performance of an earth-abundant catalysts with a renewable energy source for environmental remediation, thus meeting the requirements for a sustainable development.

Front Cover

Two-dimensional metal compounds exhibit unique properties when confined at the nanoscale, offering significant potential for electrochemical applications. In article number 2301782, Kim, Lee, and co-workers comprehensively cover recent advancements in the nanoscale structural control and electrochemical applications of materials such as TMDs, LDHs, MXenes, and their hybrids. The physicochemical properties of these materials and future challenges for high-performance electrochemical systems are also discussed.