Microfluidic technologies have emerged as advanced tools for surface‐enhanced Raman spectroscopy (SERS). They have proved to be particularly appealing for in situ and real‐time detection of analytes ...at extremely low concentrations and down to the 10 × 10−15 m level. However, the ability to prepare reconfigurable and reusable devices endowing multiple detection capabilities is an unresolved challenge. Herein, a microfluidic‐based method that allows an extraordinary spatial control over the localization of multiple active SERS substrates in a single microfluidic channel is presented. It is shown that this technology provides for exquisite control over analyte transport to specific detection points, while avoiding cross‐contamination; a feature that enables the simultaneous detection of multiple analytes within the same microfluidic channel. Additionally, it is demonstrated that the SERS substrates can be rationally designed in a straightforward manner and that they allow for the detection of single molecules (at concentrations as low as 10−14 m). Finally, it is shown that rapid etching and reconstruction of SERS substrates provides for reconfigurable and reusable operation.
A microfluidic approach for surface‐enhanced Raman spectroscopy (SERS) substrate fabrication and multiple analyte detection is presented. Combining the controlled diffusion of analytes with pneumatic clamp actuation enables the spatially controlled synthesis of custom shaped SERS substrates, where regioselective localization and detection is ensured. The method enables the reconfiguration and reuse of these substrates without cross‐contamination, hence generating SERS barcodes.
Here, a two‐step method is reported that enables imparting new functionalities to covalent organic frameworks (COFs) by nanoparticle confinement. The direct reaction between ...1,3,5‐tris(4‐aminophenyl)benzene and 1,3,5‐benzenetricarbaldehyde in the presence of a variety of metallic/metal‐oxide nanoparticles resulted in embedding of the nanoparticles in amorphous and non‐porous imine‐linked polymer organic spheres (NP@a‐1). Post‐treatment reactions of NP@a‐1 with acetic acid under reflux led to crystalline and porous imine‐based COF‐hybrid spheres (NP@c‐1). Interestingly, Au@c‐1 and Pd@c‐1 were found to be catalytically active.
Keeping nanoparticles in their place: A simple two‐step method allows encapsulating several functional nanoparticles into porous and crystalline imine‐based covalent organic framework (COF) spheres. The embedded nanoparticles are accessible to external species, thereby expanding the scope of these COF–nanoparticle hybrids to applications such as catalysis.
Abstract Covalent organic frameworks (COFs) possess intrinsic nanoscale pores, limiting mass transport and impacting their utility in many applications, such as catalysis, supercapacitors, and gas ...storage, demanding efficient diffusion throughout the material. Hierarchical porous structures, integrating larger macropores with inherent micro‐/meso‐pores, facilitate rapid mass transport. Recently, the fabrication of aerogel monoliths is reported exclusively from imine‐linked COFs, offering flexibility in aerogel composition. However, challenges in synthesizing robust β‐ketoenamine‐based COFs with comparable surface areas prompted innovative synthetic approaches. Leveraging the dynamic nature of COF bonds, in this work efficient monomer exchange from imine to partially β‐ketoenamine‐linked COFs within the gel phase is demonstrated. These aerogels can be transformed into electrodes using the compression technique. The new flexible electrodes‐based β‐ketoenamine‐linked COF composites with C super P exhibit superior durability and redox activity. Through supercapacitor assembly, the β‐ketoenamine‐linked COF electrodes outperform their imine‐based counterparts, showcasing enhanced capacitance (88 mF cm −2 ) and stability at high current densities (2.0 mA cm −2 ). These findings underscore the promise of β‐ketoenamine‐linked COFs for pseudocapacitor energy storage applications.
Abstract
Control over the functionalization of graphenic materials is key to enable their full application in electronic and optical technologies. Covalent functionalization strategies have been ...proposed as an approach to tailor the interfaces’ structure and properties. However, to date, none of the proposed methods allow for a covalent functionalization with control over the grafting density, layer thickness and/or morphology, which are key aspects for fine-tuning the processability and performance of graphenic materials. Here, we show that the no-slip boundary condition at the walls of a continuous flow microfluidic device offers a way to generate controlled chemical gradients onto a graphenic material with 2D and 3D control, a possibility that will allow the sophisticated functionalization of these technologically-relevant materials.
Antimonene, a novel group 15 two‐dimensional material, is functionalized with a tailormade perylene bisimide through strong van der Waals interactions. The functionalization process leads to a ...significant quenching of the perylene fluorescence, and surpasses that observed for either graphene or black phosphorus, thus allowing straightforward characterization of the flakes by scanning Raman microscopy. Furthermore, scanning photoelectron microscopy studies and theoretical calculations reveal a remarkable charge‐transfer behavior, being twice that of black phosphorus. Moreover, the excellent stability under environmental conditions of pristine antimonene has been tackled, thus pointing towards the spontaneous formation of a sub‐nanometric oxide passivation layer. DFT calculations revealed that the noncovalent functionalization of antimonene results in a charge‐transfer band gap of 1.1 eV.
Flake off: Reported for the first time is the noncovalent functionalization of antimonene using perylene bisimides (PDI). The significant quenching of the fluorescence of the PDI allows straightforward characterization of the antimonene flakes deposited on Si/SiO2 substrates. This work paves the way for the development of novel applications based on antimonene by tailoring its electronic properties.
Few-Layer Antimonene by Liquid-Phase Exfoliation Gibaja, Carlos; Rodriguez-San-Miguel, David; Ares, Pablo ...
Angewandte Chemie (International ed.),
November 7, 2016, Letnik:
55, Številka:
46
Journal Article
Recenzirano
Odprti dostop
We report on a fast and simple method to produce highly stable isopropanol/water (4:1) suspensions of few‐layer antimonene by liquid‐phase exfoliation of antimony crystals in a process that is ...assisted by sonication but does not require the addition of any surfactant. This straightforward method generates dispersions of few‐layer antimonene suitable for on‐surface isolation. Analysis by atomic force microscopy, scanning transmission electron microscopy, and electron energy loss spectroscopy confirmed the formation of high‐quality few‐layer antimonene nanosheets with large lateral dimensions. These nanolayers are extremely stable under ambient conditions. Their Raman signals are strongly thickness‐dependent, which was rationalized by means of density functional theory calculations.
Very stable suspensions of high‐quality single‐ or few‐layer antimonene were obtained by liquid‐phase exfoliation under sonication without the need for a surfactant. The Raman spectrum of antimonene was found to strongly depend on its thickness, which was also rationalized by quantum‐mechanical calculations.
•Covalent Organic Frameworks timeline evolution.•Strategies of preparation of Covalent Organic Frameworks.•Developments in the processability of Covalent Organic Frameworks.•Perspectives on potential ...uses of Covalent Organic Frameworks.
Covalent Organic Frameworks are highly versatile porous materials that have attracted much attention over the last few years. This review summarizes the timeline of its development, highlighting the shifts in the targets deemed necessary to use them in real-world applications. We have collected aspects concerning COF formation and the strategies developed to gain chemical stability by using different linkages between the initial building blocks and modulating the structural characteristics of COFs. Importantly, we have also included elements concerning material processability that has been incorporated in the research field of COFs but are essential to solving many different applications of COFs. Finally, we included a summary section providing headlines of this research field to get closer to real applications.
A promising way to address modern environmental and energy supply challenges is via rapid implementation of decarbonization and hydrogen production technologies. Development of gas separation ...membranes with high selectivity and permeability is essential for these processes but is still a bottleneck. Our research focuses on achieving precise control of gas diffusion pathways through on-demand regulation of material interactions in thin composite membranes. We combine 2D covalent organic frameworks (COFs) and graphene oxide (GO) to create COF-GO composite membranes with desirable nanosheet stacking, controllable thicknesses and pathways for gases. By pH-assisted self-assembly, we fine-tune material interactions and achieve simultaneous enhancement of permeability and selectivity by increasing membrane thickness and regulating the interactions between COF and GO nanosheets by pH. At a thickness of 1.3 μm, the COF-GO membrane, assembled under pH 4, demonstrates good working characteristics for H2/CO2 equimolar mixture (at room temperature and 1 bar), with a H2 permeability of 366 Barrer, selectivity of 15.6, and long-term stability exceeding 200 h. This work paves the way for tailored, performing gas separation with long-term stability. It guides the unique 2D transport mechanism to be utilized under practical conditions. Our research offers a novel strategy for the design of composite membranes from two-dimensional (2D) materials for gas separation technologies. It contributes to sustainable decarbonization and hydrogen production solutions, bringing us closer to a greener, more environmentally friendly future.
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•Sustainable, highly controllable, water-based self-assembly of COF-GO membranes.•Self-assembly regulated by COF/GO ratio and pH to form membranes with structure and gas diffusion pathway on demand.•Our strategy overcomes traditional permeability-selectivity trade-off commonly observed in gas separation membranes.
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