Two-Dimensional Sodium Channels with High Selectivity and Conductivity for Osmotic Power Generation from Wastewater.

Conducting target ions rapidly while rejecting rival ions efficiently is challenging yet highly demanded for ion separation related applications. Two-dimensional (2D) channels are widely used for ion separation, but highly selective 2D channels generally suffer from a relatively low ionic conductivity. Here we report that the 2D vermiculite channels have a Na+ conductivity higher than bulk and at the same time reject heavy metal ions with a selectivity of a few hundreds. Such performance is attributed to the highly electronegative crystal surface and the extremely narrow channel (0.2 nm high), as also supported by the ab initio molecular dynamics simulation. We demonstrate that the highly selective and conductive sodium channels can be utilized to harvest osmotic power from industrial wastewater, achieving a power density of more than 20 W m-2 while preventing pollution from waste heavy metal ions. This work provides a strategy for wastewater utilization as well as treatment. Moreover, the investigation suggests the possibility to break the ionic permeability-selectivity trade-off by combining Ångstrom-scale confinement with proper surface engineering, which could lead to applications that are challenging for previous materials.

Biomimetic Superhydrophobic Materials through 3D Printing: Progress and Challenges.

Superhydrophobicity, a unique natural phenomenon observed in organisms such as lotus leaves and desert beetles, has inspired extensive research on biomimetic materials. Two main superhydrophobic effects have been identified: the "lotus leaf effect" and the "rose petal effect", both showing water contact angles larger than 150°, but with differing contact angle hysteresis values. In recent years, numerous strategies have been developed to fabricate superhydrophobic materials, among which 3D printing has garnered significant attention due to its rapid, low-cost, and precise construction of complex materials in a facile way. In this minireview, we provide a comprehensive overview of biomimetic superhydrophobic materials fabricated through 3D printing, focusing on wetting regimes, fabrication techniques, including printing of diverse micro/nanostructures, post-modification, and bulk material printing, and applications ranging from liquid manipulation and oil/water separation to drag reduction. Additionally, we discuss the challenges and future research directions in this burgeoning field.

Non-covalent metalation of carbon nitride for photocatalytic NADH regeneration and enzymatic CO2 reduction.

An artificial photocatalyst with a Rh complex immobilized onto polymeric carbon nitride (CN) through non-covalent interaction was constructed for photocatalytic NADH regeneration. DFT calculations verified the adsorption of the bipyridine ligand onto the CN photocatalyst. By further coupling the in situ formed NADH with FDH immobilized on a hydrophobic membrane, an enhanced HCOOH production (3.1 mM) from CO2 could be realized on the gas-liquid-solid three-phase interface. This work provides an alternative and efficient strategy for promoting artificial photosynthesis.

Electric field modulated water permeation through laminar Ti3C2Tx MXene membrane.

Controlling water transport is central to a wide range of water-related energy and environment issues. In particular, enhancing the water permeation is highly demanded for practical membrane applications such as water treatment. In this work, we demonstrate that the water permeation through the laminar and electrically conductive MXene membrane can be facilely modulated with electric field. By applying a negative voltage of a few volts on the membrane, the water permeation rate was enhanced by 70 times. Density functional theory calculations and experimental characterizations suggest that the enhancement arises from the enhanced water/MXene interaction under electric field, which manifests itself as enhanced hydrophilicity of the MXene nanosheets. Along with the facilitated water permeation, the rejection rate to dyes of the membrane was kept at a relatively high level, which was 93.1% to Congo red and 94.8% to aniline blue under an applied voltage of -3 V, showing the potential for dye separation and water purification. Considering that there has been increasing interest in utilizing MXene for separations and water treatment, this work should inspire a range of future works in the related area to improve the membrane performance with external stimuli.

Biomimetic Nanochannels: From Fabrication Principles to Theoretical Insights.

Biological nanochannels which can regulate ionic transport across cell membranes intelligently play a significant role in physiological functions. Inspired by these nanochannels, numerous artificial nanochannels have been developed during recent years. The exploration of smart solid-state nanochannels can lay a solid foundation, not only for fundamental studies of biological systems but also practical applications in various fields. The basic fabrication principles, functional materials, and diverse applications based on artificial nanochannels are summarized in this review. In addition, theoretical insights into transport mechanisms and structure-function relationships are discussed. Meanwhile, it is believed that improvements will be made via computer-guided strategy in designing more efficient devices with upgrading accuracy. Finally, some remaining challenges and perspectives for developments in both novel conceptions and technology of this inspiring research field are stated.

Graphdiyne-Supported Atomic Catalysts: Synthesis and Applications.

Graphdiyne (GDY) has been ideal candidate support for atomic catalysts (ACs) due to its unique conjugated two-dimensional (2D) structure comprising both sp- and sp2 -hybrid carbon atoms. ACs/GDY can display excellent catalytic ability and high selectivity, emerging as a cutting-edge research area in the past few years. Recently, a growing body of work has been done in ACs/GDY, ranging from screening appropriate combinations theoretically, continuous improvement to prepare few-layered GDY to meet the critical challenge in this area, and successfully fabricating ACs/GDY in facile way. This Minireview briefly introduces recent advanced progress in this field, including the synthetic method for both thin GDY film and ACs/GDY, as well as theoretical analysis of different ACs/GDY systems, characterization, and applications. In the end, the challenges and further opportunities of ACs/GDY are summarized and proposed. It is hoped that this article brings new insights into the current study of ACs/GDY and promotes better development in this area.

Confined Interfacial Synthesis of Highly Crystalline and Ultrathin Graphdiyne Films and Their Applications for N2 Fixation.

Graphdiyne (GDY), as a new carbon allotrope, possessing both sp- and sp2 -hybridized carbon atoms, has attracted extensive attention due to great application potentials in various fields. To realize a fundamental understanding of the intrinsic properties of GDY, the controllable synthesis of ultrathin and highly crystalline GDY is necessary and challenging. Herein, a confined interfacial synthetic strategy towards highly crystalline ultrathin GDY at the water/oil/organogel interface, with greatly improved control over GDY structures, is reported. The morphology and chemical composition of GDY was characterized accordingly. After loading with gold, the as-prepared hydrophobic Au/GDY system showed excellent performance in the nitrogen reduction reaction, reaching the highest yield of 4.15 µg cm-2 h-1 with a Faraday efficiency of 1.95 %.

Charge transfer co-crystals based on donor-acceptor interactions for near-infrared photothermal conversion.

A co-crystal was obtained based on donor-acceptor interactions. The obvious charge transfer from the linear donor to the triangular acceptor units results in a quasi-two-dimensional CT complex with excellent near-infrared photothermal conversion efficiency. The co-crystals further acted as an excellent photothermal material in seawater desalination.

Computer-Guided Discovery of a pH-Responsive Organic Photocatalyst and Application for pH and Light Dual-Gated Polymerization.

In this work, we adopted a fully computer-guided strategy in discovering an efficient pH-switchable organic photocatalyst (OPC), unprecedentedly turning colorless at pH 5 and recovering strong visible-light absorption and photoactivity at pH 7. This is the first example of an OPC design fully guided by comprehensive density functional theory (DFT) studies covering electrostatic, electrochemical, and photophysical predictions. Characterization of the designed OPC after synthesis confirmed the computational predictions. We applied this OPC to mediate an aqueous photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization under green LED light (nominal emission wavelength: 530 nm, 5 mW/cm2). We demonstrated that the polymerization can be reversibly ceased by a slight change of pH (pH ≤ 5.0) or in the absence of light. Furthermore, we demonstrated that the polymerization rate could be significantly retarded by bubbling carbon dioxide into the reaction solution under visible light. Conversely, the rate could be fully recovered via exposure to nitrogen gas. This is the first example of a pH and light dual-gated polymerization system with complete and reversible inhibition.

Preparation of N-Graphdiyne Nanosheets at Liquid/Liquid Interface for Photocatalytic NADH Regeneration.

Two-dimensional (2D) N-graphdiyne (N-GDY) nanosheets containing different number of N were synthesized by polymerization of triazine, pyrazine, and pyridine-based monomers at liquid/liquid interface. The configurations and nanostructures of N-GDY were well-characterized. The wettability changed to more hydrophilic as the N contents increased. The collected N-GDY was further employed as metal-free photocatalyst for NADH regeneration. The catalytic performance was related with the N content in the graphdiyne. The N3-GDY demonstrated the best activity. This strategy provided a new promising platform of designing unique 2D N-GDY with tunable performance in biorelated catalysis.

Interfacial Synthesis of Conjugated Two-Dimensional N-Graphdiyne.

We explored the interfacial synthesis of 2D N-graphdiyne films at the gas/liquid and liquid/liquid interfaces. Triazine- or pyrazine-based monomers containing ethynyl group were polymerized through the Glaser coupling reactions at interfaces. Several layered, highly ordered and conjugated 2D N-graphdiyne were obtained. Their structures were characterized by TEM, SEM, AFM, XPS, and Raman spectra. Thin films with minimum thickness of 4 nm could be prepared.

Superlyophilicity-Facilitated Synthesis Reaction at the Microscale: Ordered Graphdiyne Stripe Arrays.

As a new member of carbon allotropes, graphdiyne is a promising material with excellent electronic performance and high elasticity, indicating the possibility of graphdiyne to serve as the building blocks in flexible electronics. However, precise positioning/patterning of graphdiyne is still a challenge for the realization of large-area and flexible organic electronic devices and circuits. Here, the direct in situ synthesis of patterning graphdiyne stripe arrays dominated by the superlyophilic grooved templates is reported, whereas the superlyophilicity of grooved templates plays a key role in allowing continuous mass transport of raw reactants into the microscale spacing. After the completion of cross-coupling reaction procedure, precisely patterned graphdiyne stripes can be generated accordingly. The size of graphdiyne stripe arrays is depending on the silicon substrate size (1 cm × 1.5 cm), and the layer thickness can be manipulated from just several nanometers to hundreds of nanometers by varying the primary concentration of hexaethynylbenzene monomers. As a proof-of-principle demonstration, a stretchable sensor based on the graphdiyne stripe arrays is performed to monitor the human finger motion. It is expected that this wettability-facilitated strategy will provide new insights into the controlled synthesis of graphdiyne toward promising flexible electronics and other optoelectronic applications.

A Dewetting-Induced Assembly Strategy for Precisely Patterning Organic Single Crystals in OFETs.

Simple methods for patterning single crystals are critical to fully realize their applications in electronics. However, traditional vapor and solution methods are deficient in terms of crystals with random spatial and quality distributions. In this work, we report a dewetting-induced assembly strategy for obtaining large-scale and highly oriented organic crystal arrays. We also demonstrate that organic field-effect transistors (OFETs) fabricated from patterned n-alkyl-substituted tetrachloroperylene diimide (R-4ClPDI) single crystals can reach a maximum mobility of 0.65 cm(2) V(-1) s(-1) for C8-4ClPDI in ambient conditions. This technique constitutes a facile method for fabricating OFETs with high performances for large-scale electronics applications.

A general strategy for assembling nanoparticles in one dimension.

Alignment of 1D assemblies of a wide variety of nanoparticles (e.g., metal, metal oxide, semiconductor quantum dots, or organic microspheres) in one direction upon diverse substrates (including industrial silicon wafers and transparent glass plates) by a general strategy is demonstrated. This sandwich method provides an efficient way of rapidly and precisely assembling nanoparticles on a large scale (up to 10 cm × 10 cm) for device applications.