Nanosheet Membranes Research Articles

Hydrogel-embedded vertically aligned metal-organic framework nanosheet membrane for efficient water harvesting.

Highly porous metal-organic framework (MOF) nanosheets have shown promising potential for efficient water sorption kinetics in atmospheric water harvesting (AWH) systems. However, the water uptake of single-component MOF absorbents remains limited due to their low water retention. To overcome this limitation, we present a strategy for fabricating vertically aligned MOF nanosheets on hydrogel membrane substrates (MOF-CT/PVA) to achieve ultrafast AWH with high water uptake. By employing directional growth of MOF nanosheets, we successfully create superhydrophilic MOF coating layer and pore channels for efficient water transportation to the crosslinked flexible hydrogel membrane. The designed composite water harvester exhibits ultrafast sorption kinetics, achieving 91.4% saturation within 15 min. Moreover, MOF-CT/PVA exhibits superior solar-driven water capture-release capacity even after 10 cycles of reuse. This construction approach significantly enhances the water vapor adsorption, offering a potential solution for the design of composite MOF-membrane harvesters to mitigate the freshwater crisis.

Engineering of Covalent Organic Framework Nanosheet Membranes for Fast and Efficient Ion Sieving: Charge-Induced Cation Confined Transport.

Artificial membranes with ion-selective nanochannels for high-efficiency mono/divalent ion separation are of great significance in water desalination and lithium-ion extraction, but they remain a great challenge due to the slight physicochemical property differences of various ions. Here, the successful synthesis of two-dimensional TpEBr-based covalent organic framework (COF) nanosheets, and the stacking of them as consecutive membranes for efficient mono/divalent ion separation is reported. The obtained COF nanosheet membranes with intrinsic one-dimensional pores and abundant cationic sites display high permeation rates for monovalent cations (K+, Na+, Li+) of ≈0.1-0.3mol m-2 h-1, while the value of divalent cations (Ca2+, Mg2+) is two orders of magnitude lower, resulting in an ultrahigh mono/divalent cation separation selectivity up to 130.4, superior to the state-of-the-art ion sieving membranes. Molecular dynamics simulations further confirm that electrostatic interaction controls the confined transport of cations through the cationic COF nanopores, where multivalent cations face i) strong electrostatic repulsion and ii) steric transport hindrance since the large hydrated divalent cations are retarded due to a layer of strongly adsorbed chloride ions at the pore wall, while smaller monovalent cations can swiftly permeate through the nanopores.

Highly Efficient, Flexible, and Self-Healable Moisture-Driven Energy Harvester Based on 2D Vanadium Pentoxide Nanosheets

The ubiquitous source of atmospheric moisture brought about a fascinating research avenue of extracting atmospheric water to generate sustainable electricity. Energy may be extracted from ambient moisture with obvious and substantial advantages. This point-of-use technology provides a decentralized alternative to meet the energy needs in isolated off-grid places. Unlike traditional energy generators which predominantly rely upon fossil fuel, moisture-induced energy generators can extract energy from moisture in a sustainable and eco-friendly way. Herein, we demonstrated a self-healable moist electric generator (MEG) based on vanadium pentoxide (V2O5) 2D nanosheet membranes. Lamellar membranes of V2O5 nanosheets have been shown to be excellent cation conductors and excellent materials for harvesting energy from ambient moisture. Ultra-thin 2D nanosheets of V2O5 was obtained by treatment of bulk V2O5 crystals with hydrogen peroxide. V2O5 nanosheet membrane was fabricated by vacuum-assisted filtration of 2D V2O5 nanosheets dispersion over a PTFE support membrane. The V2O5 membrane was easily peeled off from the support membrane on drying to obtain a flexible and freestanding V2O5 membrane. The V2O5 membrane consisting of percolated nanofluidic channels was sandwiched between a bottom solid copper foil and a perforated copper foil as the bottom electrode. The top electrode is perforated for exposure to atmospheric humidity. As the atmospheric water molecules come in contact with the V2O5 surface, an open-circuit voltage of 0.5 Volts and a short-circuit current of 0.3 microamperes is generated. The generated voltage and current is attributed to the preferential flow of cations through the V2O5 nanochannels. The exposed surface and edges of V2O5 nanosheets have a high negative surface charge which results in the splitting of water molecules into H3O+ and OH- ions. An electrical double layer (EDL) is established at the V2O5/water interface which selectively permits H3O+ ions through the channels. The mobile ions of the EDL transport through the nanofluidic channels creating a gradient between the two electrodes, resulting in a constant potential difference between the top and bottom electrodes which is harvested as electric current. The MEGs can be easily connected in parallel or series to enhance the current and voltage respectively. We demonstrate ten MEGs connected in series to power small electronic devices such as calculators and humidity meters. One of the key features of the V2O5 MEG is its ability to repair any physical damage to the active material owing to the water-assisted healing characteristics V2O5 membrane. Figure 1

Biomimetic designing MOFs nanosheet based membranes with self-recovery two-dimensional selective channels for specific molecules long-lasting precise separation

Two-dimensional (2D) materials-based membranes with artificial transfer channels have shown significant potential for selective separation. However, the challenges such as uncontrollable interlayer spacing and undesirable molecular sieving capabilities of 2D channels have impeded their further application in separation. Inspired by biological selectivity transport channels with proper steric and affinity sites, herein we have designed biomimetic 2D selective transport channels based on a ZIF-L nanosheet membrane. In this design, the UiO-66-NH2 nanoparticles tune the appropriate interlayer confinement and compensate for laminate framework defects of 2D selectivity transport channels, the artificial imprinting recognition sites establishes the essential chemical environment for specific separation. As a result, the obtained MOFs nanosheet based membranes with imprinted recognition sites (MN-IMs) exhibited enhanced permeation flux (J = 1.0847 × 10−3 and 1.0423 × 10−3 mg min−1 cm−2) and permselectivity (α = 3.77 and 4.10), outperforming state-of-the-art similar technologies. Besides, the composite MOFs demonstrated good photoinduced self-recovery ability, which also enables MN-IMs to have long-lasting selective separation performance (the separation efficiency is 90.76 %) in the continuous separation process. This study introduces a novel design strategy for developing sophisticated 2D materials-based membranes and offers new insights into the precise separation of specific molecules.

Electrochemically assisted preparation of graphitic carbon nitride nanosheet membranes for efficient water purification

The development of a highly effective nanofiltration membrane for water purification is crucial for wastewater recovery. The graphitic carbon nitride (g-C3N4) membrane can be an ideal candidate for advanced water treatment due to its intrinsic porous structure and superior physicochemical stability. However, the developments of the g-C3N4 membranes are limited by their traditional preparation methods involving complicated processes, long reaction time and high-temperature conditions. A simple electrochemical-assisted strategy for the rapid preparation of the g-C3N4 nanosheet membranes at room temperature has been developed in this study. The ultra-thin g-C3N4 membrane with a uniform structure can be synthesized within 40 min, which is at least 7 times quicker compared to the traditional methods. The as-prepared g-C3N4 membrane shows a high water flux rate of ∼ 90 L m−2 h−1 bar−1. Simultaneously, an excellent rejection rate of 99.1% toward Evans blue is achieved based on the synergistic effect of size sieving and electrostatic repulsion. The breakthrough in the preparation method of g-C3N4 nanosheet membranes in this work is of great significance to the development of g-C3N4 membranes in the field of water purification.

Hydrogen-Bonded Metal-Organic Framework Nanosheet as a Proton Conducting Membrane for an H2/O2 Fuel Cell.

Proton-conducting metal-organic frameworks (MOFs) have attracted attention as potential electrolytes for fuel cells. However, research progress in utilizing MOFs as electrolytes for fuel cells has been limited, mainly due to challenges associated with issues such as the fabrication of MOF membranes, and hydrogen crossover through the MOF's pores. Here, proton conductivity and fuel cell performance of a self-standing membrane prepared from of a bismuth subgallateMOF nanosheets with non-porous structure are reported. The fabricated MOF nanosheet membrane with no binding agent exhibits structural anisotropy. The proton conductivity in the membrane thickness direction (4.4×10-3Scm-1) at 90°C and RH 100% is observed to be higher than that in the in-plane direction of the membrane (3.3×10-5Scm-1). The open circuit voltage (OCV) of a fuel cell with ≈120µm proton conducting membrane is 1.0V. The non-porous nature of the MOF nanosheets contributes to the relatively high OCV. A fuel cell using ≈40µm membrane as proton conducting electrolyte records a maximum of 25mWcm-2 power density and a maximum of 109mAcm-2 current density with 0.91V OCV at 80°C in humid conditions.

Ultrathin Two‐Dimensional Porous Fullerene Membranes for Ultimate Organic Solvent Separation

AbstractTwo‐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.

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.

A computational investigation of DMSO/water separation through functionalized GO multilayer nanosheet membrane using molecular dynamics simulation and deep neural network model for membrane performance prediction

In this molecular dynamics (MD) simulation study, the separation of dimethyl sulfoxide (DMSO) from water was investigated using multilayer functionalized graphene oxide (GO) membranes. The GO nanosheets were modified with chemical groups (-F, -H) to alter their properties. The study analyzed the influence of pressure and functional groups on the separation rate. Additionally, a deep neural network (DNN) model was developed to predict membrane behavior under different conditions in water treatment processes. Results revealed that the fluorine-functionalized membrane exhibited higher permeation compared to the hydrogen-functionalized one, with potential of mean force (PMF) analysis indicating higher energy barriers for water molecules passing through the hydrogen-functionalized membrane. The study used density profile, water density map analysis, and radial distribution function (RDF) analysis to understand water and DMSO molecule interactions. The diffusion coefficient of water molecules was also calculated, showing higher diffusion in the fluorine-functionalized system. Overall, the findings suggest that functionalized GO membranes are effective for DMSO-water separation, with the fluorine-functionalized membrane showing superior performance. The DNN model accurately predicts membrane behavior, contributing to the optimization of membrane separation systems.

MOF-derived 2D Co@C nanosheet membrane with enhanced catalytic activity: Mechanism and stability insights

Two-dimensional (2D) metal-organic frameworks (MOFs) membranes have recently gained attention as novel material membranes for advanced oxidation processes (AOPs). Nonetheless, the susceptibility of 2D MOFs to reactive oxygen species (ROS) limits 2D MOF membranes’ effectiveness in AOPs. In this study, we introduce a novel approach, fabricating a 2D Co-MOF-derived nanosheet membrane (referred to as Co@C NS), assembled from pyrolyzed and exfoliated Co-MOF nanosheets, for the activation of peroxymonosulfate (PMS) in the removal of bisphenol A (BPA). Crucially, the synthesis process involves the pyrolysis of a carbon layer, serving as a protective barrier. This barrier effectively prevents the release of Co ions, ensuring the long-term structural and catalytic stability of the Co@C NS membrane. Notably, the membrane exhibits remarkable capabilities in discriminating between natural organic matter (NOM) and BPA through size exclusion, significantly mitigating the impact of NOM competition for ROS. Additionally, our study demonstrates an exceptional removal efficiency, achieving 100% BPA removal at an ultrahigh permeance of 1100 L m−2 h−1 bar−1, corresponding to an exceedingly short retention time of 0.14 s. Our mechanistic investigation reveals the involvement of singlet oxygen and sulfate radicals in the removal of BPA within the nanochannels, facilitated by the nanoconfinement effect. This study introduces valuable strategies for the development of 2D MOF-derived nanosheet membranes characterized by high catalytic activity and excellent stability, underlining their practical potential in AOP applications.

Dual-module integration of large-area tubular 2D MXene membranes for H2 purification

Construction of large-area two-dimensional (2D) nanosheet membranes for gas separation, particularly tubular membranes, is extremely challenging. Here, electrophoretic deposition technology was employed to construct large-area tubular 2D MXene membranes for H2/CO2 gas separation, where the membrane with a single tube area of 25 cm2 could be successfully manufactured in approximately 5 min under optimal process conditions. The membrane exhibited good H2/CO2 separation performance with H2/CO2 selectivity of 53.0 and hydrogen permeance of 133.8 GPU, exceeding the 2008 Robeson upper bound, and showed excellent stability in long-term test with water vapor evaluations for more than 350 h. Additionally, some engineering issues and operation parameters concerning the separation performance of H2/CO2 in single-module and dual-module separators have been thoroughly investigated and analyzed. This work has taken an important step toward the industrialization of 2D MXene membranes and also provided significant guidance to other 2D material-based membranes in approaching practical applications.

Tuning the Stacking Modes of Ultrathin Two‐Dimensional Metal–Organic Framework Nanosheet Membranes for Highly Efficient Hydrogen Separation

AbstractTwo‐dimensional (2D) metal–organic framework (MOF) membranes are considered potential gas separation membranes of the next generation due to their structural diversity and geometrical functionality. However, achieving a rational structure design for a 2D MOF membrane and understanding the impact of MOF nanosheet stacking modes on membrane separation performance remain challenging tasks. Here, we report a novel kind of 2D MOF membrane based on [Cu2Br(IN)2]n (IN=isonicotinato) nanosheets and propose that synergetic stacking modes of nanosheets have a significant influence on gas separation performance. The stacking of the 2D MOF nanosheets is controlled by solvent droplet dynamic behaviors at different temperatures of drop coating. Our 2D MOF nanosheet membranes exhibit high gas separation performances for H2/CH4 (selectivity >290 with H2 permeance >520 GPU) and H2/CO2 (selectivity >190 with H2 permeance >590 GPU) surpassing the Robeson upper bounds, paving a potential way for eco‐friendly H2 separation.

Tuning the Stacking Modes of Ultrathin Two-Dimensional Metal-Organic Framework Nanosheet Membranes for Highly Efficient Hydrogen Separation.

Two-dimensional (2D) metal-organic framework (MOF) membranes are considered potential gas separation membranes of the next generation due to their structural diversity and geometrical functionality. However, achieving a rational structure design for a 2D MOF membrane and understanding the impact of MOF nanosheet stacking modes on membrane separation performance remain challenging tasks. Here, we report a novel kind of 2D MOF membrane based on [Cu2 Br(IN)2 ]n (IN=isonicotinato) nanosheets and propose that synergetic stacking modes of nanosheets have a significant influence on gas separation performance. The stacking of the 2D MOF nanosheets is controlled by solvent droplet dynamic behaviors at different temperatures of drop coating. Our 2D MOF nanosheet membranes exhibit high gas separation performances for H2 /CH4 (selectivity >290 with H2 permeance >520 GPU) and H2 /CO2 (selectivity >190 with H2 permeance >590 GPU) surpassing the Robeson upper bounds, paving a potential way for eco-friendly H2 separation.

Holey Ti3C2Tx nanosheets membrane with high PM removal efficiency for air pollution

Developing air filters with high efficiency, low airflow resistance, good chemical and thermal stability is a great challenge for PM purification applications. MXene membranes with controlled interlayer nano-channels and abundant hydrophilic groups exhibit excellent separation potential. However, the easy stacking between neighboring nanosheets in two-dimensional lamellar membranes increases the resistance during the separation process. In this study, metal oxides were assembled with Ti3C2Tx nanosheets by electrostatic interaction, and holey Ti3C2Tx (H-Ti3C2Tx) nanosheets with abundant through-hole structures were prepared by calcination and etching with a specific surface of 13.2 m2g−1, 6 times higher than that of Ti3C2Tx (2.2 m2g−1). H-Ti3C2Tx nanosheet membranes with transverse and longitudinal channels were produced using vacuum filtering. The membrane has excellent PM filtration performance, with filtration efficiency higher than 94.59% for PM 0.3 and 99.97% for PM 2.5 and 99.99% for PM 10.0, respectively, and the pressure drop of 120 Pa after 12 h of operation, which is better than that of pure Ti3C2Tx membrane (>1300 Pa). Excellent PM filtration was also demonstrated under high humidity conditions. Our findings provide a scalable strategy for the synthesis of holes MXene materials as well as demonstrate their potential in air purification.

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.

Graphitic carbon nitride membranes intercalated with nano-sized Fe-MOF for enhanced water purification via synergistic separation and Fenton-like processes

Versatile two-dimensional nanomaterials have offered a promising prospect to enhance the water purification efficiency and overcome the fouling obstacle in membrane technology. In this work, a graphitic carbon nitride (g-C3N4) nanosheet membrane intercalated with the nano-sized Fe-based metal-organic framework (MIL-100(Fe)) is developed for the enhanced removal of aqueous organic contaminants by synergically promoting separation and Fenton-like processes. The g-C3N4/MIL-100(Fe) membrane is constructed through a self-assembly route in which the nano-MIL-100(Fe) is anchored into g-C3N4 layers by the coordination bonds between Fe nodes and pyridinic N. The MIL-100(Fe) intercalation not only enlarges the interlayer spacing to raise the membrane permeability, but also expedites the electron transfer between Fe2+ and Fe3+ to improve the Fenton-like activity. With a stable water flux of 98.2 L m2·h−1·bar−1 under wide-range pH and pressures, the g-C3N4/MIL-100(Fe) membrane shows high dye removal efficiency (≥99%) and prominent self-cleaning ability. Mechanism insight proposes a combination of size exclusion, electrostatic interaction and steady radical generation. The intercalation of nano-MIL-100(Fe) into g-C3N4 membranes can realize the mutual promotion between separation and Fenton-like processes, the synergistic effect of which provides an effective and feasible strategy for aqueous pollution abatement.

Tunable Photoluminescence of Bismuth‐ and Trivalent‐Lanthanide‐Doped Monolayer Perovskite Oxide Nanosheets

AbstractMulticolor photoluminescent Bi0.4Ln0.1Na0.5Ta2O72− nanosheets (Ln = Eu, Tb, Dy, Sm, La) are prepared by delaminating an Aurivillius‐phase layered perovskite, Bi2.4Ln0.1Na0.5Ta2O9. Both Bi3+ and Ln3+ (except La3+) successfully function as luminescent centers under UV‐light illumination (λex. = 240–340 nm), which result in a photoluminescence color that can be tuned by changing the lanthanide doping. The emission spectra are influenced by pH because the energy distribution to Ln3+ or to Bi3+ is different in acidic or in basic solutions. Freestanding Bi0.4Ln0.1Na0.5Ta2O72− nanosheet membranes are prepared by vacuum filtration, and the relationship between the photoluminescence and structural properties of the nanosheet membranes is investigated. The results indicate that differences in the electron orbitals involved in the photoluminescence of Bi3+ (6s2–6s6p) and Ln3+ (4fn–4fn) influence the responsiveness to changes in the environment surrounding those luminescent centers.

Superhigh and Robust Ion Selectivity in Membranes Assembled with Monolayer Clay Nanosheets.

It is crucial to control the ion transport in membranes for various technological applications such as energy storage and conversion. The emerging functional two-dimensional (2D) nanosheets such as graphene oxide and MXenes show great potential for constructing ordered nanochannels, but the assembled membranes suffer from low ion selectivity and stability. Here a class of robust charge-selective membranes with superhigh cation/anion selectivity, which are assembled with monolayer nanosheets of cationic/anionic clays that inherently have permanent and uniform charges on each layer is reported. The transport number of cations/anions of cationic vermiculite nanosheet membranes (VNMs)/anionic Co-Al layered double hydroxide (CoAl-LDH) nanosheet membranes is over 0.90 in different NaCl concentration gradients, outperforming all the reported ion-selective membranes. Importantly, this excellent ion selectivity can persist at high-concentration salt solutions, under acidic and alkaline conditions, and for a wide range of ions of different sizes and charges. By coupling a pair of cation-selective vermiculite membrane and anion-selective CoAl-LDH membrane, a reverse electrodialysis device which shows an output power density of 0.7W m-2 and energy conversion efficiency of 45.5% is constructed. This work provides a new strategy to rationally design high-performance ion-selective membranes by using 2D nanosheets with inherent surface charges for controllable ion-transport applications.

IRMOF-3 nanosheet-filled glass fiber membranes for efficient separation of hydrogen and carbon dioxide

Metal-organic framework (MOF) nanosheets have been identified as promising membrane materials for various separation applications. However, the development of MOF nanosheet membranes for practical applications is impeded by the difficulties in preparing ultrathin nanosheets and the limitations of conventional membrane production methods. For the first time, conveniently prepared and purified isoreticular MOF-3 (IRMOF-3) nanosheets are filled into macroporous glass fiber (GF) filters to prepare IRMOF-3 nanosheet-filled GF (IRMOF-3@GFX, X = filling amount expressed in mg) membranes. The IRMOF-3@GF2.0 membrane exhibits an impressively high H2/CO2 selectivity of 1341 ± 134, and the H2 permeance reaches 974 ± 41 gas permeance units (GPU). In addition, the IRMOF-3@GF2.0 membrane shows excellent durability with no performance degradation during a 150-h test. Grand Canonical Monte Carlo simulations are performed to investigate the H2/CO2 separation mechanism and the results suggest a synergistic separation mode based on selective adsorption and size exclusion. The innovative filled-membrane fabrication route and the presented gas separation mechanism offer a new strategy to design and prepare MOF nanosheet-based gas separation membranes.

Structure Regulation of MOF Nanosheet Membrane for Accurate H2/CO2 Separation

AbstractHigh‐purity H2 production accompanied with a precise decarbonization opens an avenue to approach a carbon‐neutral society. Metal–organic framework nanosheet membranes provide great opportunities for an accurate and fast H2/CO2 separation, CO2 leakage through the membrane interlayer galleries decided the ultimate separation accuracy. Here we introduce low dose amino side groups into the Zn2(benzimidazolate)4 conformation. Physisorbed CO2 served as interlayer linkers, gently regulated and stabilized the interlayer spacing. These evoked a synergistic effect of CO2 adsorption‐assisted molecular sieving and steric hinderance, whilst exquisitely preserving apertures for high‐speed H2 transport. The optimized amino membranes set a new record for ultrathin nanosheet membranes in H2/CO2 separation (mixture separation factor: 1158, H2 permeance: 1417 gas permeation unit). This strategy provides an effective way to customize ultrathin nanosheet membranes with desirable molecular sieving ability.