In-plane Pores Research Articles

In-situ confined preparation of COF@GO nanofiltration membranes for high-efficiency dye removal

Graphene oxide membrane (GOM) possesses ultrafast and tunable two-dimensional water transport pathways, making it an ideal candidate for nanofiltration separation of dye wastewater. However, GOM also faces great challenges such as poor aqueous stability, collapse of non-oxygenated regions under high pressure, and limitations imposed by trade-off effects. In this study, covalent organic frameworks (COFs) were in-situ formed within GOM interlayers and on membrane surface to enlarge interlayer spacings and enhance hydrophilicity of GOM simultaneously via a two-step method including monomer retention in GOM and in-situ confined interfacial polymerization of COFs. Fourier transformation infrared spectroscopy (FT-IR) and X-ray photoelectron spectrometry (XPS) results confirmed the successful synthesis of COF on GOM surface, which enhanced membrane surface hydrophilicity and bridged the split defects of GOM. According to X-ray diffraction measurements (XRD) and scanning electron microscope (SEM) results, COF@GO membranes possessed enlarged interlayer spacings and increased thickness of selective layer, which indicated the successful intercalation of COF into GO interlayer. COF@GO-50 membrane exhibited an ultrahigh pure water permeability (PWP) of 148.1 L/(m2·h·bar), with 99.0 % rejection for direct red 80 (DR80) aqueous solution and 9.6 % NaCl rejection. The ultrahigh water permeance might be ascribed to the enlarged interlayer pathways, the shortened vertical pathways provided by in-plane pores of COF nanosheets, and enhanced water adsorption capacity due to enhanced membrane hydrophilicity. Moreover, COF@GO nanofiltration membrane demonstrated excellent anti-fouling properties and long-term stability in 30h continuous operation, maintaining considerable separation efficiency under harsh conditions. This work provides a straightforward and applicable strategy to simultaneously enlarge interlayer spacings and enhance surface hydrophilicity of GOM via in-situ confined preparation of COFs, achieving ultrahigh water permeance and overcoming the trade-off effect between permeability and selectivity of GOM.

Polyelectrolyte intercalated two-dimensional covalent organic framework membranes for efficient desalination

Two-dimensional covalent organic frameworks (2D COFs) have been proven to be ideal membrane materials for highly efficient separation. However, synergistic manipulation of the in-plane pores and interlayer channel structures of 2D COF membranes (COFMs) to acquire both high permeability and selectivity has rarely been reported. In this work, we synthesized TbTG COF nanosheets with intrinsic sub-nanometer pores, which were assembled with polyelectrolytes to form intercalated 2D COFMs. The sub-nanometer in-plane pores of the COF nanosheets endowed the COFM with size sieving capacity toward hydrated multivalent ions. The polyelectrolyte introduces numerous charged groups to the interlayer channels, enhancing the Donnan effect for desalination and also enlarging the interlayer distance to facilitate permeability. Accordingly, the in-plane pores and interlayer channels of the 2D COFM were synergistically engineered to simultaneously enhance the selectivity and permeability of COFMs. By adjusting the polyelectrolytes with different charged groups, the intercalated COFMs exhibited a high Na2SO4 rejection of 97.5 % and MgCl2 rejection of 99.4 %, respectively, as well as about a fourfold increase in permeability. Compared with the pure COFM. This work highlights the significance of interlayer channel structure of 2D COFMs for precise separations, providing new guidelines on the design and construction of advanced COFMs.

Synergy of modulating in-plane pores and zincophilic sites on the flexible graphene paper for efficient and dendrite-free hosted Zn anode

The practical advancement of Zn-ion batteries (ZIBs) in the portable/wearable electronics field is still hindered by the notorious Zn dendrites formation and the lack of an appropriate host to construct a highly effective flexible Zn anode. Herein, we present a three-dimensional (3D) N-doped graphene paper framework with abundant in-plane pores (rHGP-N) as an efficient Zn plating/stripping scaffold. Remarkably, the rHGP-N paper electrode exhibits an unprecedentedly low Zn nucleation overpotential of 5.2 mV and maintains a high average Coulombic efficiency (∼99.3%) over a superior long Zn plating/stripping cycling of 1400 h. DFT calculation results demonstrate that pyrrolic-nitrogen on graphene possesses the strongest adsorption energy for Zn2+, serving as zincophilic sites to guide Zn uniform nucleation. Moreover, the finite elements simulation results illustrate that flexible graphene paper with abundant in-plane pores can mitigate structural stress and inhibit the formation of Zn dendrites by spatially homogenizing Zn2+ ions flux throughout the entire electrode. The assembled ZIBs full cell (rHGP-N@Zn//rHGP-N@Mn3(PO4)2) demonstrates an impressive volumetric energy density of 77 mWh/cm3, as well as excellent flexibility and mechanical stability with negligible capacity decay under harsh deformation conditions. Our approach can be potentially utilized in designing dendrite-free metal-based flexible anodes for Mg, Ca, or Al-ion batteries.

Ultrathin Two-Dimensional Porous Fullerene Membranes for Ultimate Organic Solvent Separation.

Two-dimensional (2D) materials with high chemical stability have attracted intensive interest in membrane design for the separation of organic solvents. As a novel 2D material, polymeric fullerenes (C60)∞ with distinctive properties are very promising for the development of innovative membranes. In this work, we report the construction of a 2D (C60)∞ nanosheet membrane for organic solvent separation. The pathways of the (C60)∞ nanosheet membrane are constructed by sub-1-nm lateral channels and nanoscale in-plane pores created by the depolymerization of the (C60)∞ nanosheets. Attributing to ordered and shortened transport pathways, the ultrathin porous (C60)∞ membrane is superior in organic solvent separation. The hexane, acetone, and methanol fluxes are up to 1146.3±53, 900.4±41, and 879.5±42 kg ⋅ m-2 ⋅ h-1, respectively, which are up to 130 times higher than those of the state-of-the-art membranes with similar dye rejection. Our findings demonstrate the prospect of 2D (C60)∞ as a promising nanofiltration membrane in the separation of organic solvents from macromolecular compounds such as dyes, drugs, hormones, etc.

Porous rGO/networked cellulose composite membranes: Towards enhanced nanofiltration performance of rGO-based membranes

Graphene-based materials have been widely used for the fabrication of superior separation membranes for water treatment and purification. In particular, reduced graphene oxide (rGO), which has better water stability than graphene oxide (GO), has been demonstrated to be a good building block. However, rGO laminates are characterized by narrow interlayer spacing leading to dense packing and consequently lower flux limiting their direct utilization for membrane development. In this study, we report the fabrication of networked cellulose (NC)/porous rGO composite membranes with enhanced separation performance. We observed a synergistic effect due to the incorporation of NC and the presence of nano-pores on the rGO sheets. Firstly, in addition to the enhanced hydrophilicity and mechanical stability, the presence of NC with networked fibers reduced the horizontal transport resistance within the interlayer channels due to the formation of voids and wrinkles. Secondly, in-plane pores created by H2O2 oxidation of GO effectively contributed to additional transport channels providing shortened transport length for water molecules. Results showed that composite membranes maintained stable long-term performance with a pure water permeance up to 25.1 ± 2.2 Lm−2h−1bar−1 and salt rejection of 70.2 %, 63.08 %, 17.13 % and 25.62 %, for Na2SO4, MgSO4, MgCl2 and NaCl respectively. Unlike many previously reported rGO membranes that rely on ultra-thin selective layers, this work demonstrates an effective strategy for fabricating superior rGO membranes for water treatment and desalination.

Biopolyphenol stabilized CoFe2O4-rGO/GO catalytic cleaning membrane for fast and high-efficiency contaminants removal

Utilizing membrane materials for the purification of wastewater represents an effective approach to address water scarcity. Nonetheless, the issues of membrane fouling and stability hinder their widespread application. Herein, an effective biopolyphenols (PP) modification strategy was proposed to construct strongly stable cobalt ferrite-loaded graphene oxide (CoFe2O4-rGO-PP/GO) membranes with catalytic cleaning function. Compared with the membranes without PP modification, the incorporation of polymerized tannic acid (pTA), green tea polyphenol (GTP), and black tea polyphenol (BTP) significantly improved membrane separation efficiencies of methylene blue (MB), with high removal reaching 99.11, 98.92, and 99.20 %, respectively. Notably, the CoFe2O4-rGO-pTA/GO membrane demonstrated high rejection and outstanding permeability of 167.2 L m−2 h−1 bar−1. Introducing pTA, GTP, and BTP could enhance MB degradation rate constants by 61.54, 38.46, and 19.23 % via peroxymonosulfate (PMS) activation, respectively. Remarkably, CoFe2O4-rGO-pTA/GO membrane achieved near-complete MB degradation within 12 min. Moreover, CoFe2O4-rGO-PP/GO membranes maintained high MB rejection exceeding 97 % even after ten cycles, highlighting exceptional stability and catalytic cleaning performance. The separation mechanism of these membranes was dominantly governed by the nano-confined adsorption under pressure-driven flow-through process, which was greatly distinguished from a size-sieving mechanism of densely stacked 2D lamellar membranes replying on their in-plane pores or interlayer nano/subnano-channels. This PP modification strategy can be extended to design diversified 2D lamellar membranes with guest intercalation, to achieve high stability, superior separation and multi-function.

Detection and identification of single ribonucleotide monophosphates using a dual in-plane nanopore sensor made in a thermoplastic via replication.

We report the generation of ∼8 nm dual in-plane pores fabricated in a thermoplastic via nanoimprint lithography (NIL). These pores were connected in series with nanochannels, one of which served as a flight tube to allow the identification of single molecules based on their molecular-dependent apparent mobilities (i.e., dual in-plane nanopore sensor). Two different thermoplastics were investigated including poly(methyl methacrylate), PMMA, and cyclic olefin polymer, COP, as the substrate for the sensor both of which were sealed using a low glass transition cover plate (cyclic olefin co-polymer, COC) that could be thermally fusion bonded to the PMMA or COP substrate at a temperature minimizing nanostructure deformation. Unique to these dual in-plane nanopore sensors was two pores flanking each side of the nanometer flight tube (50 × 50 nm, width × depth) that was 10 μm in length. The utility of this dual in-plane nanopore sensor was evaluated to not only detect, but also identify single ribonucleotide monophosphates (rNMPs) by using the travel time (time-of-flight, ToF), the resistive pulse event amplitude, and the dwell time. In spite of the relatively large size of these in-plane pores (∼8 nm effective diameter), we could detect via resistive pulse sensing (RPS) single rNMP molecules at a mass load of 3.9 fg, which was ascribed to the unique structural features of the nanofluidic network and the use of a thermoplastic with low relative dielectric constants, which resulted in a low RMS noise level in the open pore current. Our data indicated that the identification accuracy of individual rNMPs was high, which was ascribed to an improved chromatographic contribution to the nano-electrophoresis apparent mobility. With the ToF data only, the identification accuracy was 98.3%. However, when incorporating the resistive pulse sensing event amplitude and dwell time in conjunction with the ToF and analyzed via principal component analysis (PCA), the identification accuracy reached 100%. These findings pave the way for the realization of a novel chip-based single-molecule RNA sequencing technology.

MXene nanomesh for high-performance supercapacitor

The merits of excellent electrical conductivity, good hydrophilicity, and large specific capacitances render MXene film electrodes attractive in supercapacitors (SCs). However, the tortuous ion transfer in restacked nanosheets limits the electrochemical performance of dense film electrodes. To solve the ion transfer issue, we propose a strategy to produce porous films assembled by Ti3C2 nanomesh via the chemical oxidation-etching process. The rich in-plane pores in Ti3C2 nanomesh provide abundant pathways and new active sites for ion transfer/adsorption, greatly improving the electrochemical activity. Specifically, the obtained Ti3C2 nanomesh films exhibit high specific capacitances of 235 F g-1 at 1 A g-1 and 184 F g-1 at 10 A g-1 in 6 M KOH, which are ∼2 times higher than the pristine Ti3C2 films (118 F g-1 at 1 A g-1 and 90 F g-1 at 10 A g-1). Furthermore, hybrid capacitors, composed of the Ti3C2 nanomesh films as the negative electrodes and Ni-Co layered double hydroxides as the positive electrodes, in KOH electrolytes, are also demonstrated to show practicability. This work provides an opportunity to develop high-performance energy storage devices with the 2D nanomesh.

Constructing defective-functionalized g-C3N4 homojunction for efficient photocatalytic detoxification of lemon yellow in an aqueous solution and beverage.

The content of food colorant in food and environment should be limited to a safe range. Thus, cost-effective, and environmental-friendly detoxification technology is urgent for food safety and environmental protection. In this work, defective-functionalized g-C3N4 was successfully fabricated via intermediate engineering strategy. The prepared g-C3N4 possesses large specific surface area with abundant in-plane pores. Carbon vacancy and N-CO unit are introduced into g-C3N4 molecular framework, endowing the different degrees of n-type conductivity in varied domains. And then the n-n homojunction is generated. This homojunction structure is demonstrated to be efficient in separation and transfer of photoinduced charge carriers, and causes enhanced photocatalytic detoxification of lemon yellow under visible light. Furthermore, as-prepared g-C3N4 in lemon tea enable completely removed lemon yellow without obvious effect on its overall acceptability. The findings deepen the understanding on the defect-induced self-functionality of g-C3N4, and prove the application potential of photocatalytic technology in contaminated beverages.

Precisely regulated in-plane pore sizes of Co-MOF nanosheet membranes for efficient dye recovery

Nanofiltration (NF) is widely used to treat highly saline textile waters, but its efficiency in dye recovery is limited by low permeance. This study presents a novel class of Co-based metal-organic framework (Co-MOF) nanosheet membranes for efficient and selective dye recovery. The Co-MOF membranes have precisely regulated in-plane pore sizes and exhibit superior permeance and selectivity compared to non-porous nanosheet membranes. By adjusting the length of the ligand, the in-plane pore size was precisely tuned from 1.01 × 0.63 to 1.43 × 0.64 nm2. The Co-MOF membranes exhibited high selectivity for salts over dye in both diffusion and pressure-driven filtration modes, along with excellent and tunable pure water permeance and high rejection of the dye OII. The remarkable permeability and selectivity of the Co-MOF membranes were attributed to the in-plane pores on the nanosheets, which serve as extra fast “lifts” for water and salts while exhibiting high rejection to the dye molecules. Long-term filtration performance and Co leaching tests demonstrated the stability of the Co-MOF membranes, making them promising candidates for practical dye recovery applications. Overall, this work provides a new approach for the development of high-performance membranes for textile wastewater treatment.

Metal cation cross-linked 3D frameworks of Fe3O4 nanospheres encapsulated in graphene nanomesh with enhanced anode performance for lithium-ion batteries

Transition metal oxide (TMO) particles encapsulated in graphene shell has been reported to be an ideal lithium-ion batteries (LIBs) anode due to its well TMO particles volumetric adaptability upon cycling. In this paper, to further enhance the structural stability as well as electrochemical performance of Fe3O4-based electrodes for LIBs, 3D composite structures of Fe3O4 nanospheres (NSs) encapsulated in interconnected holey graphene nanosheets (Ca2+/p-rGO@Fe3O4) were fabricated by facile hydrothermal process using Ca2+ as crosslinker and hydrogen peroxide (H2O2) as etching agent. The composite was characterized by X-ray diffractometer (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Fourier Transform Infrared Spectrometer (FTIR), and other test methods. The morphological and structural tests show that Fe3O4 NSs are homogenously embedded in the 3D framework of interconnected graphene nanomesh aerogels. Based on its unique structure, the Ca2+/p-rGO@Fe3O4 composite electrode delivers an initial discharge and charge capacities of 1288 and 783 mA h g−1, respectively, remarkable rate capability at current densities from 0.1 to 2 A g−1 and excellent cyclic stability with respect to that of its counterparts Ca2+/rGO@Fe3O4 electrode, p-rGO@Fe3O4 electrode and rGO@Fe3O4 electrode, which are prepared using a similar synthetic procedure but without the addition of H2O2 or CaCl2 or neither. It is proved that the synergistic effects of Ca2+-induced crosslinking reaction at the edge of GO nanosheets and in-plane pores on graphene coated on the surface of Fe3O4 can enhance the whole electrochemical performance of anode for LIBs.

High Sensitivity Extended Nano-Coulter Counter for Detection of Viral Particles and Extracellular Vesicles.

We present a chip-based extended nano-Coulter counter (XnCC) that can detect nanoparticles affinity-selected from biological samples with low concentration limit-of-detection that surpasses existing resistive pulse sensors by 2-3 orders of magnitude. The XnCC was engineered to contain 5 in-plane pores each with an effective diameter of 350 nm placed in parallel and can provide high detection efficiency for single particles translocating both hydrodynamically and electrokinetically through these pores. The XnCC was fabricated in cyclic olefin polymer (COP) via nanoinjection molding to allow for high-scale production. The concentration limit-of-detection of the XnCC was 5.5 × 103 particles/mL, which was a 1,100-fold improvement compared to a single in-plane pore device. The application examples of the XnCC included counting affinity selected SARS-CoV-2 viral particles from saliva samples using an aptamer and pillared microchip; the selection/XnCC assay could distinguish the COVID-19(+) saliva samples from those that were COVID-19(-). In the second example, ovarian cancer extracellular vesicles (EVs) were affinity selected using a pillared chip modified with a MUC16 monoclonal antibody. The affinity selection chip coupled with the XnCC was successful in discriminating between patients with high grade serous ovarian cancer and healthy donors using blood plasma as the input sample.

Two-Dimensional Interlayer Space Induced Horizontal Transformation of Metal-Organic Framework Nanosheets for Highly Permeable Nanofiltration Membranes.

Laminar membranes comprising graphene oxide (GO) and metal-organic framework (MOF) nanosheets benefit from the regular in-plane pores of MOF nanosheets and thus can support rapid water transport. However, the restacking and agglomeration of MOF nanosheets during typical vacuum filtration disturb the stacking of GO sheets, thus deteriorating the membrane selectivity. Therefore, to fabricate highly permeable MOF nanosheets/reduced GO (rGO) membranes, a two-step method is applied. First, using a facile solvothermal method, ZnO nanoparticles are introduced into the rGO laminate to stabilize and enlarge the interlayer spacing. Subsequently, the ZnO/rGO membrane is immersed in a solution of tetrakis(4-carboxyphenyl)porphyrin (H2 TCPP) to realize in situ transformation of ZnO into Zn-TCPP in the confined interlayer space of rGO. By optimizing the transformation time and mass loading of ZnO, the obtained Zn-TCPP/rGO laminar membrane exhibits preferential orientation of Zn-TCPP, which reduces the pathway tortuosity for small molecules. As a result, the composite membrane achieves a high water permeance of 19.0Lm-2 h-1 bar-1 and high anionic dye rejection (>99% for methyl blue).

Engineering fast water-selective pathways in graphene oxide membranes by porous vermiculite for efficient alcohol dehydration

Graphene oxide (GO) lamellar membranes with well-aligned architecture hold promising potential for molecular separations. However, the tortuous transport pathways and weak interlamellar interactions between stacked GO nanosheets cause low flux and poor stability, which are major drawbacks for their practical applications. Herein, we report a strategy to engineer fast and robust water-selective pathways within GO-based lamellar membranes by porous vermiculite (PVMT), a naturally layered magnesium aluminosilicate. PVMT nanosheets conferred abundant in-plane pores, which decreased the tortuosity and shortened the mass transport distance inside lamellar membranes. Meanwhile, PVMT nanosheets enhanced the hydrophilicity and fixed the interlayer distance, contributing to robust water-selective transport. The physicochemical properties of membranes, such as thickness and hydrophilicity, were manipulated by the loading amount of PVMT nanosheets. The resulting lamellar membranes exhibited excellent n-butanol dehydration performance with a permeation flux of 9554 g m−2 h−1 and a separation factor of 2678, which increased by up to 91% and 328% compared to pristine GO/PTFE membranes. Moreover, membranes remain stable for 192 h operation. Our study may stimulate further research on precise construction of mass-transfer pathways within lamellar membranes.

Holey Ti3C2 MXene-Derived Anode Enables Boosted Kinetics in Lithium-Ion Capacitors.

Lithium-ion capacitors (LICs) attract enormous attention because of the urgent demands for high power and energy density devices. However, the intrinsic imbalance between anodes and cathodes with different charge-storage mechanisms blocks the further improvement in energy and power density. MXenes, novel two-dimensional materials with metallic conductivity, accordion-like structure, and regulable interlayer spacing, are widely employed in electrochemical energy storage devices. Herein, we propose a holey Ti3C2 MXene-derived composite (pTi3C2/C) with enhanced kinetics for LICs. This strategy effectively decreases the surface groups (-F and -O) and generates expanded interplanar spacing. The in-plane pores of Ti3C2Tx lead to increased active sites and accelerated lithium-ion diffusion kinetics. Benefiting from the expanded interplanar spacing and accelerated lithium-ion diffusion, the pTi3C2/C as an anode implements excellent electrochemical property (capacity retention about 80% after 2000 cycles). Furthermore, the LIC fabricated with a pTi3C2/C anode and an activated carbon cathode displays a maximum energy density of 110 Wh kg-1 and a considerable energy density of 71 Wh kg-1 at 4673 W kg-1. This work provides an effective strategy to achieve high antioxidant capability and boosted electrochemical properties, which represents a new exploration of structural design and tuneable surface chemistry for MXene in LICs.

Scalable Synthesis of Holey Deficient 2D Co/NiO Single-Crystal Nanomeshes via Topological Transformation for Efficient Photocatalytic CO2 Reduction.

Preparation of holey, single-crystal, 2D nanomaterials containing in-plane nanosized pores is very appealing for the environment and energy-related applications. Herein, an in situ topological transformation is showcased of 2D layered double hydroxides (LDHs) allows scalable synthesis of holey, single-crystal 2D transition metal oxides (TMOs) nanomesh of ultrathin thickness. As-synthesized 2D Co/NiO-2 nanomesh delivers superior photocatalytic CO2 -syngas conversion efficiency (i.e., VCO of 32460µmol h-1 g-1 CO and of 17840µmol h-1 g-1 H2 ), with VCO about 7.08 and 2.53 times that of NiO and 2D Co/NiO-1 nanomesh containing larger pore size, respectively. As revealed in high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), the high performance of Co/NiO-2 nanomesh primarily originates from the edge sites of nanopores, which carry more defect structures (e.g., atomic steps or vacancies) than basal plane for CO2 adsorption, and from its single-crystal structure adept at charge transport. Theoretical calculation shows the topological transformation from 2D hydroxide to holey 2D oxide can be achieved, probably since the trace Co dopant induces a lattice distortion and thus a sharp decrease of the dehydration energy of hydroxide precursor. The findings can advance the design of intriguing holey 2D materials with well-defined geometric and electronic properties.

Graphene oxide membranes with short-range pore channels toward ultrafast water transport via γ-ray etching

Graphene oxide (GO) has the characteristics of easy membrane formation and adjustable interlayer size, which can achieve molecular/ion separation precisely. However, the stacked GO nanosheets have a large tortuosity factor and long mass transfer channel, which limits the feasibility of GO membranes with high-flux. In this study, we propose the short-range pore channels construction strategy that a γ-ray irradiation pore-making technology is used to increase the in-plane porosity of GO nanosheets, thereby shortening the mass transfer channel and realizing the rapid transmission of water molecules. The in-plane defects and d-spacing of GO, used as the mass transfer channel of the membrane, were finely controlled by the irradiation dose of γ-rays. More in-plane pores and expanded interlayer pathway was introduced into the membrane by adjusting the irradiation dose, which leads to significantly strengthened water permeability. The optimized membrane has a higher pure water permeability (345.23 L m-2h−1 bar−1) and dye rejection (nearly 100 %) as well as excellent dye/salt separation performance (αmax: 109.27), which is superior to GO membranes previous reported in the literature. The porous membrane with short-range pore channels obtained by high-energy irradiation provides a new strategy for preparing two-dimensional membranes with efficient wastewater purification and recovery.

Scalable anisotropic cooling aerogels by additive freeze-casting

Cooling in buildings is vital to human well-being but inevitability consumes significant energy, adding pressure on achieving carbon neutrality. Thermally superinsulating aerogels are promising to isolate the heat for more energy-efficient cooling. However, most aerogels tend to absorb the sunlight for unwanted solar heat gain, and it is challenging to scale up the aerogel fabrication while maintaining consistent properties. Herein, we develop a thermally insulating, solar-reflective anisotropic cooling aerogel panel containing in-plane aligned pores with engineered pore walls using boron nitride nanosheets by an additive freeze-casting technique. The additive freeze-casting offers highly controllable and cumulative freezing dynamics for fabricating decimeter-scale aerogel panels with consistent in-plane pore alignments. The unique anisotropic thermo-optical properties of the nanosheets combined with in-plane pore channels enable the anisotropic cooling aerogel to deliver an ultralow out-of-plane thermal conductivity of 16.9 mW m−1 K−1 and a high solar reflectance of 97%. The excellent dual functionalities allow the anisotropic cooling aerogel to minimize both parasitic and solar heat gains when used as cooling panels under direct sunlight, achieving an up to 7 °C lower interior temperature than commercial silica aerogels. This work offers a new paradigm for the bottom-up fabrication of scalable anisotropic aerogels towards practical energy-efficient cooling applications.

MXene/Graphdiyne nanotube composite films for Free-Standing and flexible Solid-State supercapacitor

MXene with excellent flexibility, metallic conductivity, and ultra-high capacitance, makes a promising electrode for flexible supercapacitor. But the serious restacking phenomenon between MXene layers undesirably limits the ion transport kinetics and substantially reduces ion storage sites, badly restricting the rate capability and storage capacity of supercapacitor. Here, we constructed a free-standing, flexible, structurally 3D-interconnected and hydronium ion penetrable MXene/Graphdiyne nanotube (MG) composite film by employing graphdiyne nanotubes (GDY-NTs) with inherent in-plane pores for horizontal-vertical intercalation among MXene layers. Benefiting from the above synergistic effect, this composite film presents a greatly-improved capacitance of 337.4 F g−1 (337.4 C g−1) and an obviously-enhanced rate capability of 73 %-remaining at 100 mV s−1, which is much better than those of the pure Ti3C2Tx films (230.8 F g−1, 55 %-remaining). Based on it, we developed an asymmetric solid-state flexible supercapacitor with a high energy density of 19.7 Wh kg−1 at the power density of 750 W kg−1 and a capacitance retention of 88.2 % after 10 000 cycles at 8 A g−1. Evidently, this work provides a new route to solve the restacking issue of MXene for high-performance flexible supercapacitor.

Towards High-Performance Supercapacitor Electrodes via Achieving 3D Cross-Network and Favorable Surface Chemistry.

Transition metal phosphides/phosphates (TMPs) are considered appealing electrode materials in energy-related fields, especially in supercapacitors. However, the dilemma of inadequate electrode kinetics and dimensional unreliability evoked by a huge volume variation during cycling significantly plagues their progress. To mitigate this issue, in this work, a 3D cross-network in situ assembled via self-derived N-doped carbon hybrid Ni-Co-P/POx 2D sheets is fabricated. Particularly, high-Fermi-level N-doped carbon well confines Ni-Co-P/POx nanoparticles at the molecular level, and N-doping leads to redistribution of spin/electron density in the carbon skeleton, effectively regulating the electron environment of nearby Ni-Co-based moieties, resulting in a relatively lower surface work function, as known via experimental and Kelvin probe force microscopy (KPFM) results, which favors electron flee from the electrode surface and facilitates electron transport toward a rapid supercapacitor response. Moreover, the well-defined 3D cross-network architectures featured with in-plane pores and interconnected with each other can provide more ion/electron transfer pathways and 2D sheets with excellent surface chemistry available for sustainable ion/electron mobility, synergistically affording the favorable electrode kinetics. Accordingly, the resultant Ni-Co-P/POx@NC electrode shows admirable specific capacitance, excellent rate survivability, and long-term cyclability. The as-assembled asymmetric device exhibits remarkable energy and power outputs (48.5 Wh kg-1 and 7500 W kg-1), superior to many reported devices. Furthermore, our devices possess the prominent ability to power a commercial electronic thermometer for 1560 s at least, showcasing superb application prospects.