Nanofluidic devices have been widely used for diode‐like ion transport and salinity gradients energy conversion. Emerging reverse electrodialysis (RED) nanofluidic systems based on nanochannel membrane display great superiority in salinity gradient energy harvesting. However, the imbalance between permeability and selectivity limits their practical application. Here, a new mesoporous carbon‐silica/anodized aluminum (MCS/AAO) nanofluidic device with enhanced permselectivity for temperature‐ and pH‐regulated energy generation was obtained by interfacial super‐assembly method. A maximum power density of 5.04 W m−2 is achieved, and a higher performance can be obtained by regulating temperature and pH. Theoretical calculations are further implemented to reveal the mechanism for ion rectification, ion selectivity and energy conversion. Results show that the MCS/AAO hybrid membrane has great superiority in diode‐like ion transport, temperature‐ and pH‐regulated salinity gradient energy conversion.
The rational design and controllable synthesis of hollow nanoparticles with both a mesoporous shell and an asymmetric architecture are crucially desired yet still significant challenges. In this work, a kinetics-controlled interfacial super-assembly strategy is developed, which is capable of preparing asymmetric porous and hollow carbon (APHC) nanoparticles through the precise regulation of polymerization and assembly rates of two kinds of precursors. In this method, Janus resin and silica hybrid (RSH) nanoparticles are first fabricated through the kinetics-controlled competitive nucleation and assembly of two precursors. Specifically, silica nanoparticles are initially formed, and the resin nanoparticles are subsequently formed on one side of the silica nanoparticles, followed by the co-assembly of silica and resin on the other side of the silica nanoparticles. The APHC nanoparticles are finally obtained via high-temperature carbonization of RSH nanoparticles and elimination of silica. The erratic asymmetrical, hierarchical porous and hollow structure and excellent photothermal performance under 980 nm near-infrared (NIR) light endow the APHC nanoparticles with the ability to serve as fuel-free nanomotors with NIR-light-driven propulsion. Upon illumination by NIR light, the photothermal effect of the APHC shell causes both self-thermophoresis and jet driving forces, which propel the APHC nanomotor. Furthermore, with the assistance of phase change materials, such APHC nanoparticles can be employed as smart vehicles that can achieve on-demand release of drugs with a 980 nm NIR laser. As a proof of concept, we apply this APHC-based therapeutic system in cancer treatment, which shows improved anticancer performance due to the synergy of photothermal therapy and chemotherapy. In brief, this kinetics-controlled approach may put forward new insight into the design and synthesis of functional materials with unique structures, properties, and applications by adjusting the assembly rates of multiple precursors in a reaction system.
The capture of sustainable energy from a salinity gradient, in particular, using renewable biomass-derived functional materials, has attracted significant attention. In order to convert osmotic energy to electricity, many membrane materials with nanofluidic channels have been developed. However, the high cost, complex preparation process, and low output power density still restrict the practical application of traditional membranes. Herein, we report the synthesis of highly flexible and mechanically robust nanofiber-arrays-based carbonaceous ordered mesoporous nanowires (CMWs) through a simple and straightforward softtemplating hydrothermal carbonization approach. This sequential superassembly strategy shows a high yield and great versatility in controlling the dimensions of CMWs with the aspect ratio changes from about 3 to 39. Furthermore, these CMWs can be used as novel building blocks to construct functional hybrid membranes on macroporous alumina. This nanofluidic membrane with asymmetric geometry and charge polarity exhibits low resistance and highperformance energy conversion. This work opens a solution-based route for the one-pot preparation of CMWs and functional heterostructure membranes for various applications.
Asymmetric hollow and magnetic mesoporous silica nanocomposites have great potential applications due to their unique structural-functional properties. Here, asymmetric multilayer-sandwich magnetic mesoporous silica nanobottles (MMSNBs) are presented through an interfacial super-assembly strategy. Asymmetric hollow silica nanobottles (SNBs) are first prepared, and Fe 3 O 4 nanoparticles monolayers and mesoporous silica layers are uniformly super-assembled on the surfaces of SNBs, respectively. The high Fe 3 O 4 nanoparticles loading endows MMSNBs with a high magnetization (8.5 emu g −1 ), while the mesoporous silica layers exhibit high surface area (613.4 m 2 g −1 ) and large pore size (3.6 nm). MMSNBs can be employed as a novel type of enzyme-powered nanomotors by integrating catalase (Cat-MMSNBs), which show an average speed of 7.59 µm s −1 (≈25 body lengths s −1 ) at 1.5 wt% H 2 O 2 . Accordingly, the water quality can be monitored by evaluating the movement speed of Cat-MMSNBs. Moreover, MMSNBs act as a good adsorbent for removing more than 90% of the heavy metal ions with the advantage of the mesoporous structure. In addition, the good magnetic response enables the MMSNBs with precise directional control and is conducive to recycling for repeated operation. This bottom-up interfacial super-assembly construction strategy allows for a new understanding of the rational design and synthesis of multi-functional nanomotors.
Hydrogen evolution reaction (HER) through water splitting is a potential technology to realize the sustainable production of hydrogen, yet the tardy water dissociation and costly Pt-based catalysts inhibit its development. Here, a trapping–bonding strategy is proposed to realize the superassembly of surface-enriched Ru nanoclusters on a phytic acid modified nitrogen-doped carbon framework (denoted as NCPO-Ru NCs). The modified framework has a high affinity to metal cations and can trap plenty of Ru ions. The trapped Ru ions are mainly distributed on the surface of the framework and can form Ru nanoclusters at 50 °C with the synergistic effect of vacancies and phosphate groups. By adjusting the content of phytic acid, surface-enriched Ru nanoclusters with adjustable distribution and densities can be obtained. Benefiting from the adequate exposure of the active sites and dense distribution of ultrasmall Ru nanoclusters, the obtained NCPO-Ru NCs catalyst can effectively drive HER in alkaline electrolytes and show an activity (at overpotential of 50 mV) about 14.3 and 9.6 times higher than that of commercial Ru/C and Pt/C catalysts, respectively. Furthermore, the great performance in solar to hydrogen generation through water splitting provides more flexibility for wide applications of NCPO-Ru NCs.
Osmotic energy existing between seawater and freshwater is a potential blue energy source that can mitigate the energy crisis and environmental pollution problems. Nanofluidic devices are widely utilized to capture this blue energy owing to their unique ionic transport properties in the nanometer scale. However, with respect to nanofluidic membrane devices, high membrane inner resistance and a low power density induced by disordered pores and thick coating as well as difficulty in manufacturing still impede their real-world applications. Here, we demonstrate an interfacial super-assembly strategy that is capable of fabricating ordered mesoporous silica/macroporous alumina (MS/AAO) framework-based nanofluidic heterostructure membranes with a thin and ordered mesoporous silica layer. The presence of a mesoporous silica layer with abundant silanol and a high specific surface area endows the heterostructure membrane with a low membrane inner resistance of about 7 KΩ, excellent ion selectivity, and osmotic energy conversion ability. The power density can reach up to 4.50 W/m2 by mixing artificial seawater and river water through the membrane, which is 20 times higher than that of the conventional 2D nanofluidic membrane, and outperforms about 30% compared to other 3D porous membranes. More intriguingly, the interesting pH-sensitive osmotic energy conversion property of the MS/AAO membrane is subsequently recognized, which can realize a higher power density even in acidic or alkaline wastewater, expanding the application range, especially in practical applications. This work presents a valuable paradigm for the use of mesoporous materials in nanofluidic devices and provides a way for large-scale production of nanofluidic devices.
physical/chemical functionalization is capable of optimization of mechanical properties, [7] interfacial adhesion, [8] and self-healing ability of hydrogels. [9] These protocols normally introduced functional elements or structures that elicited physical/chemical interactions for the performance improvements of hydrogels. For example, polymeric nanoparticles from crystallization-driven self-assembly enabled mechanical improvements on hydrogel by physical hybridization with matrix. [10] Grafting silica nanoparticles to a double-network polymer also improved the hydrogel mechanical performances. [11] Construction of electrostatic interaction between carboxyl groups and various surfaces resulted in a catechol-chemistrybased hydrogel for the long-term adhesiveness. [12] Treatment by metal ions resulted in a hydrophobic surface that promoted formation of a water-resistant molecular bridge between the hydrogel surface and hydrophobic domains on the substrates, endowing the hydrogels prominent underwater-adhesion capability. [13] Similar adhesive hydrogel could also be achieved by dopamine-modified clay nanosheets. [14] An effective molecular structure design based on acid-ether hydrogen bonding and imine bonds was capable of accelerating hydrogel healing time to 30 min. [15] A dynamic borate bond in network enabled 100% cure of hydrogel in air. [16] Reversible metal-ligand coordination bonding interaction could also be used to construct self-healing hydrogel. [17] These protocols are efficient for the construction of functional hydrogels, yet still challenging to synchronously improve the mechanical strength, self-healing, and interfacial adhesion of a hydrogel, and especially, hard to endow the hydrogel with modular sensitivity to external pressure. Therefore, the development of a new class of protocol is still essential.Herein, we proposed an electrochemistry functionalization protocol, in which the functional improvements on hydrogels were achieved by the electrode reactions, and electrochemistrytriggered ionic and molecular migration. This protocol was capable of enabling the function improvements of the hydrogel in mechanical strength, interfacial adhesion, and self-healing. In the meantime, it allowed generation of various patterns on the hydrogel surface, and endowed the hydrogel modular sensitivity to external pressure. The functional improvements Hydrogels have demonstrated great potential in biomedical and engineering areas. To improve the physical performance, development of efficient physical/chemical protocols is essential. Herein, an electrochemistry functionalization strategy that is capable of enabling the functional improvements of hydrogel is reported. The electrochemistry functionalization is demonstrated on a hydrogel model of polyacrylamide (PAAm)@κ-carrageenan. The electrochemistry reaction generates metal ions (Fe 3+ ) that migrate and coordinate with the sulfate groups of κ-carrageenan resulting in the prominent function improvements. In comparison with untreated PAAm@κcarrageenan hydrogel, it c...
Boron nanoclusters and few‐layer borophenes have received considerable attention in recent years due to their unique structural and bonding patterns. Based on extensive global searches and density‐functional theory calculations, we present herein the possibility of a new series of bilayer medium‐sized boron clusters including C2 B54 (I), C2h B60 (II), and C1 B62 (III) in a universal structural pattern, with one, two, and three B6 hexagonal windows on the waist around a B38 bilayer hexagonal prism at the center, respectively. Detailed orbital and bonding analyses indicate that these three‐dimensional aromatic bilayer clusters follow the σ + π double delocalization bonding pattern, with three or four effective interlayer B–B σ‐bonds formed to further stabilize the system. The IR, Raman, and UV/Vis spectra of the bilayer species are theoretically simulated to facilitate their future spectral characterizations.
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