Composite Membranes Research Articles

Flexible Multimodal Sensors Enhanced by Electrospun Lead-Free Perovskite and PVDF-HFP Composite Form-Stable Mesh Membranes for In Situ Plant Monitoring.

The pH and humidity of the crop environment are essential indicators for monitoring crop growth status. This study reports a lead-free perovskite/polyvinylidene fluoride-hexafluoropropylene composite (LPPC) to enhance the stability and reliability of in situ plant pH and humidity monitoring. The mesh composite membrane of LPPC illustrates a hydrophobic contact angle of 101.982°, a tensile strain of 800%, and an opposing surface potential of less than -184.9 mV, which ensures fast response, high sensitivity, and stability of the sensor during long-term plant monitoring. The LPPC-coated pH electrode possesses a sensitivity of -63.90 mV/pH, which provides a fast response within 5 s and is inert to environmental temperature interference. The LPPC-coated humidity sensor obtains a sensitivity of -145.7 Ω/% RH, responds in 28 s, and works well under varying light conditions. The flexible multimodal sensor coated with an LPPC membrane completed real-time in situ monitoring of soilless strawberries for 17 consecutive days. Satisfactory consistency and accuracy performance are observed. The study provides a simple solution for developing reliable, flexible wearable multiparameter sensors for in situ monitoring of multiple parameters of crop environments.

Photocatalytic hydrogen evolution on tubular shape cellulose acetate/crystalline nanocellulose/polyvinyl alcohol membranes with embedded nanocrystalline catalysts

In this work, we design an efficient and cost-effective porous membrane composed by polymeric blend that supports different photocatalytic materials. The thin (300 μm) porous photocatalytic membrane has a tubular shape and was flexible for easy handle in the reactor. The membrane is composed of a polymeric blend based on cellulose acetate, crystalline nanocellulose and polyvinyl alcohol, obtained by the phase inversion method, using cold water as non-solvent. Bismuthates (KBiO3, NaBiO3) and aluminates (ZnAl2O4 and Cu0·9Zn0·1Al2O4) powders were synthesized by diverse methodologies and were embedded into polymeric matrix. The hydrogen evolution performance of photocatalyst powders and photocatalytic composite membranes, under UV light irradiation during 180 min, were compared. The best result of hydrogen evolution was obtained by Cu0·9Zn0·1Al2O4 powders reaching 117.74 μmolg−1h−1 and the M−CuZn membrane reaching 90.07 μmolg−1h−1. The obtained results show the high potential of these polymeric membranes as a green alternative support for photocatalysts for hydrogen evolution.

Multiscale Approach for Tuning Communication among Chemical Oscillators Confined in Biomimetic Microcompartments.

ConspectusInspired by the biological world, new cross-border disciplines and technologies have emerged. Relevant examples include systems chemistry, which offers a bottom-up approach toward chemical complexity, and bio/chemical information and communication technology (bio/chemical ICT), which explores the conditions for propagating signals among individual microreactors separated by selectively permeable membranes. To fabricate specific arrays of microreactors, microfluidics has been demonstrated as an excellent method. In particular, droplet-based microfluidics is a powerful tool for encapsulating biological entities and chemical reagents in artificial microenvironments, mostly water-in-oil microdroplets. In these systems, the interfaces are liquid-liquid, and their physicochemical properties are key factors for tuning the coupling between molecular diffusion. Simple and double emulsions, where aqueous domains are in equilibrium with oil domains through boundary layers of amphiphilic molecules, are organized assemblies with high interfacial-area-to-volume ratios. These membranes can be engineered to obtain different surface charges, single- or multilayer stacking, and a variable degree of defects in molecular packing. Emulsions find application in many fields, including the food industry, pharmaceutics, and cosmetics. Furthermore, micro- and nanoemulsions can be used to model the propagation of chemical species through long distances, which is not only vital for cell signaling but also significant in molecular computing. Here we present in-depth research on the faceted world of solutions confined in restricted environments. In particular, we focused on the multiscale aspects of structure and dynamics from molecular to micro and macro levels. The Belousov-Zhabotinsky chemical reaction, known for its robustness and well-documented oscillatory behavior, was selected to represent a generic signal emitter/receiver confined within microenvironments separated by liquid-liquid interfaces. In this pulse generator, the temporal and spatial progressions are governed by periodic fluctuations in the concentration of chemical species, which act as activatory or inhibitory messengers over long distances. When organized into "colonies" or arrays, these micro-oscillators exhibit emergent dynamical behaviors at the population level. These behaviors can be finely tuned by manipulating the geometrical distribution of the oscillators and the properties of the interfaces at the nanoscale. By carefully selecting the membrane composition, it is possible to drive the system toward either in-phase, antiphase, or mixed synchronization regimes among individual oscillators, depending on messenger molecules. This relatively simple lab-scale model replicates some of the communication strategies commonly found in biological systems, particularly those based on the passive diffusion of chemical and electrical signals. It can help shed light on fundamental life processes and inspire new implementations in molecular computing and smart materials.

Control of G protein–coupled receptor function via membrane-interacting intrinsically disordered C-terminal domains

G protein-coupled receptors (GPCRs) control intracellular signaling cascades via agonist-dependent coupling to intracellular transducers including heterotrimeric G proteins, GPCR kinases (GRKs), and arrestins. In addition to their critical interactions with the transmembrane core of active GPCRs, all three classes of transducers have also been reported to interact with receptor C-terminal domains (CTDs). An underexplored aspect of GPCR CTDs is their possible role as lipid sensors given their proximity to the membrane. CTD-membrane interactions have the potential to control the accessibility of key regulatory CTD residues to downstream effectors and transducers. Here, we report that the CTDs of two closely related family C GPCRs, metabotropic glutamate receptor 2 (mGluR2) and mGluR3, bind to membranes and that this interaction can regulate receptor function. We first characterize CTD structure with NMR spectroscopy, revealing lipid composition-dependent modes of membrane binding. Using molecular dynamics simulations and structure-guided mutagenesis, we then identify key conserved residues and cancer-associated mutations that modulate CTD-membrane binding. Finally, we provide evidence that mGluR3 transducer coupling is controlled by CTD-membrane interactions in live cells, which may be subject to regulation by CTD phosphorylation and changes in membrane composition. This work reveals an additional mechanism of GPCR modulation, suggesting that CTD-membrane binding may be a general regulatory mode throughout the broad GPCR superfamily.

PH controllably induced PPTA/PEMs composite nanofiltration membranes for long-term acid-resistant separation

In this study, we deposited polyelectrolyte multilayers (PEMs) on Poly (p-phenylene terephthamide) (PPTA) ultrafiltration (UF) substrates with strong polyelectrolytes (PEs): polystyrene sulfonic acid (PSS) and poly (diallyldimethylammonium chloride) (PDADMAC). The growth pattern of PEMs was shifted from linear to exponential by changing substrate potential, which was attributed to synergism and antagonism of dispersion of PEs on hydrophilic substrates and electrostatic interaction between PEs and substrates. Eventually, PEMs of layer-dominated and pore-dominated regimes were successfully obtained. We focused on the transition from the pore-dominated to the layer-dominated regime of PEMs. The PEMs nanofiltration (NF) membranes in this situation showed a better separation performance due to the together work of the interface and in-pore energy barriers. The retention rate of Na2SO4 and MgSO4 was 98 % and 91 %. The eosin Y retention rate was 99.9 % and only declined 2 % after 100 h. The hindered deposition of pore-dominated regimes led to denser and thinner layers, which achieved long-term acid resistance. It maintained a stable salt retention after 185 h cross-filtration of 0.1 M H2SO4 feed solution. The performance of PEMs NF membrane was improved from a new perspective, and excellent acid-resistant nanofiltration membranes were obtained, which are expected to be used to treat industrial acidic wastewater.

High permeability Performance TFC Nanofiltration Membrane with Two dimensional Nanochannels Support Layer Fabricated by Dissolving of Nanosheets

A synthesized thin film composite (TFC) nanofiltration membrane was prepared by incorporating Mg(OH)2 nanosheets at different ratios (from 0 to 0.5 wt%) into polysulfone (PSf) support layer. The polypiperazinamide (PPA) layer was prepared on the polysulfone support layer by means of interfacial polymerization. Then TFC membrane was then etched with H2SO4 and a PPA selective layer was established using trimesoyl chloride (TMC) and piperazine (PIP). The characterization results show that the modifications of the PSf substrate with Mg(OH)2 alter the physicochemical properties of the poly(piperazine amide) selective layer. Through the introduction of Mg(OH)2, the hydrophilicity of the TFC membrane was increased (WCA: 20.5°), promoting more linear polypiperinamide. The addition of 0.4 wt% Mg(OH)₂ to the PSf substrate, followed by sulfuric acid etching, resulted in a 196 % increase in membrane flux and with Na₂SO₄ retention at 97.72 %. The change in matrix composition favoured the generation of a lighter and rougher selective layer. The two-dimensional nanochannels in the support layer provided additional channels for water molecule transport. The membrane with two-dimensional nanochannels exhibited excellent resistance to contamination, with a flux recovery of 92.8 % for bovine serum albumin (BSA).

Synthesis of SrAl2O4: Eu, DY @ polymer composite membrane using eugenol as a cross-linking agent to minimize nanoparticle agglomeration

Synthesis of SrAl2O4: Eu, DY @ polymer composite membrane using eugenol as a cross-linking agent to minimize nanoparticle agglomeration

Chemistry of zeolites and zeolite based composite membranes as a cutting-edge candidate for removal of organic dyes & heavy metal ions: Progress and future directions

The quality of water has become a serious concern due to excessive industrial effluent production and poor wastewater treatment. Membrane technology has received immense attention due to its mild operating conditions, and highly efficient process. Polymer-based membranes are generally applied in various separation operations for their highly reproducible fabrication and low-cost approaches. Fouling aspects and the trade-off between selectivity and permeability are the main disadvantages of polymeric membranes. In this regard, zeolites are an attractive and promising candidate with 3D crystalline microporous systems, large and medium-pore molecular sieves, low-cost, and due to their distinct framework, are considered potential ceramic membranes for water treatment. Incorporating inorganic zeolite particles into the polymer matrix improves permeability while maintaining selectivity, and promotes mechanical strength in challenging environments and fouling conditions. Zeolite-based composite membranes can remove heavy metals and dye effluents from the aqueous medium thanks to their high adsorption capability and well-defined pore size. In this review, we focused on the significance of membranes in water treatment, structural/chemical features of zeolite-based membranes, and their design. The various strategies involved in integrating zeolites to obtain composite based membranes, an overview of toxicity issues of dyes, and heavy metals followed by an exploration of zeolite based composite membranes for the treatment of various dyes and heavy metal pollutants. Also, we tried to provide a cost analysis of zeolite-based membranes followed by commercial and industrial outlooks. Lastly, conclusion and future perspectives are drawn for the zeolite-based composite membranes.

Construction of X-Co-tri@SSNF reinforced PPS composite proton exchange membranes and their performance in fuel cells

In this study, we pioneered the introduction of benzophenone (DPK) as a solid solvent into polyphenylene sulfide (PPS) melt-blown, which effectively reduced the PPS melt-blown processing temperature and significantly improved the coefficients of variation of PPS melt-blown nonwoven materials. X-Co-tri@SSNF proton exchange membranes with excellent performance were prepared by functionalized modification of PPS melt-blown fabric as a substrate. The structure and properties of X-Co-tri@SSNF proton exchange membranes were systematically characterized. The results demonstrate that the 1-Co-tri@SSNF PEM exhibited a high proton conductivity of 0.183 S cm−1 at 80 °C and high humidity, significantly higher than the commercial Nafion 117 (0.135 S cm−1). Due to the heat resistance of PPS itself and the continuous dense network structure substrate of PPS nonwoven fabrics as well as the high compatibility with the membrane casting liquid, the hybrid membrane interfaces were tightly connected, so it makes the hybrid membrane perform better in terms of mechanical stability (tensile strength of 36.7 MPa), methanol permeability (4.78 × 10−7 cm2 s−1), selectivity (16.32 × 104 S s cm−3), and thermal stability (thermal decomposition temperature of around 450 °C). In addition, the 1-Co-tri@SSNF membrane electrode module exhibited excellent single-cell performance with an open-circuit voltage of 629.91 V and a peak power density of 96.29 mW cm−2 (162.9 % higher than that of Nafion 117). Therefore, the composite PEM with PPS melt-blown fabric as the matrix has a more environmentally friendly process than the commercial Nafion 117 membrane, a theoretical guidance for advancing the large-scale production of low-cost PEM.

Control of Microporous Structure in Conjugated Microporous Polymer Membranes for Post‐Combustion Carbon Capture

AbstractMembranes offer a potentially energy‐efficient and space‐saving solution to reduce CO2 emissions and combat global warming. However, engineering membranes with advanced materials for high permeance and reasonable selectivity is a pressing need. In this context, a series of carbazole‐based conjugated microporous polymer (CMP) membranes are fabricated with thicknesses of a few hundred nanometers through in situ electropolymerization for post‐combustion carbon capture. The findings reveal that various experimental conditions, including the monomer concentration, electric potential, and cyclic voltammetry (CV) cycling number, largely impact the polymerization degree of the carbazole‐based CMP, thus influencing the mode of polymer chain packing. An optimal polymerization degree leads to a larger micropore size and a higher fractional free volume (FFV), thus allowing fast CO2 transport. The study first demonstrates the feasibility of using CMPs to fabricate thin film composite (TFC) membranes for post‐combustion carbon capture and confirms the high controllability of their micropores. These insights provide instructive guidance for the future advancement of CMP applications in membrane fabrication for gas separation and other fields that require precise micropore generation and design.

Dual-aeolotropic electrically conductive flexible composite membrane with enhanced red fluorescence

New-typed dual-aeolotropic conductive flexible composite membrane (DCFCM), was devised and fabricated by parallel electrospinning. DCFCM consists of two layers that are strongly coupled to form a top-to-bottom structure. Janus nanoribbon (JN), possessing two distinct sides (respectively conducting and insulating-fluorescent side), is highly oriented in each layer of DCFCM. The top-to-bottom structure of DCFCM effectuates the macro-level zoning, and the JN as a conductive and constitutive function in DCFCM realizes the micro-level zoning, which achieves the combination of microstructure and macroscopic structure in DCFCM. Thus, DCFCM simultaneously performs dual-aeolotropic electrical conduction and enhanced red luminescence due to the partitioning structures which aid in minimizing adverse interactions between the conductive and luminescent materials. The conducting anisotropy of each layer in the DCFCM can be adjusted by varying the PANI content. The conductance ratio can reach 108 when the PANI content is 60–70 %. Additionally, DCFCM exhibits strong red emission, originating from the allowed 5D0→7F2 (593 nm), 5D0→7F2 (616 nm) energy levels transitions of Eu3+ ions. This work provides a simple and effective method to fabricate aeolotropic conductive membranes with novel multifunctional properties.

Analytical and experimental study on bilayer membrane-type Capacitive Micromechanical Ultrasonic Transducer

In this work, analytical and experimental studies on thin bilayer membrane-type Capacitive Micromechanical Ultrasonic Transducer (CMUT) have been carried out, and results are reported and discussed. The bilayer membrane, consisting of two layers — one of PMMA and the other of graphene — is the key component of the designed CMUT. Because of its high diameter/thickness ratio and relative thinness, the PMMA/graphene membrane primarily relies on tension-induced restoring force. A membrane-type model is constructed for the bilayer circular membranes and the PMMA/graphene composite membrane’s vibrational properties have been determined from the motion characteristics of rectangular and circular shaped membranes. The outcomes of the FEA simulation validate the accuracy of the theoretical analysis. A CMUT based on an ultra-thin PMMA/graphene membrane was designed and fabricated by combining graphene with PMMA to form a bi-layered structure. Subsequently, a CMUT based on the PMMA/graphene composite membrane was developed. The fundamental frequency of the fabricated device is 1.69 MHz, closely agreeing with theoretical predictions based on simulation results.

Novel zirconium phosphate/MXene/ionic liquid membranes for PEM fuel cells operating up to 145°C

In this work, zirconium phosphate, MXene, and a hexyl-based ionic liquid were incorporated into a porous PTFE polymer to synthesize novel composite proton exchange membranes (PEM) for fuel cell applications. The synthesized composite membranes were evaluated for their conductivity at temperatures above the boiling point of water as well as their water uptake properties, thermal stability, surface morphology, and structural characteristics via several characterization techniques. It was observed that the inclusion of MXene had a direct impact on the thermal stability of these membranes and caused substantial structural modifications within the membrane’s matrix. The fabricated membranes displayed a high proton conductivity at room temperature, reaching a peak of approximately 10−2 S/cm when all materials were combined. The membranes exhibited good proton conductivity of 10−4 S/cm at high temperature ranges up to 145℃ and appeared to be stable at higher temperatures, as thermogravimetric analyses showed. The results reported here demonstrate the suitability of the MXene-based synthesized membranes for hydrogen-fueled PEM fuel cell applications. This, in turn, will contribute to enhanced energy efficiency and cleaner energy transition.

Production and stability of cultured red blood cells depends on the concentration of cholesterol in culture medium

The production of cultured red blood cells (cRBC) for transfusion purposes requires large scale cultures and downstream processes to purify enucleated cRBC. The membrane composition, and cholesterol content in particular, are important during proliferation of (pro)erythroblasts and for cRBC quality. Therefore, we tested the requirement for cholesterol in the culture medium during expansion and differentiation of erythroid cultures with respect to proliferation, enucleation and purification by filtration. The low cholesterol level (22 µg/dl) in serum free medium was sufficient to expand (pro)erythroblast cultures. Addition of 2.0 or 5.0 mg/dL of free cholesterol at the start of differentiation induction inhibited enucleation compared to the default condition containing 3.3 mg/dl total cholesterol derived from the addition of Omniplasma to serum free medium. Addition of 5.0 mg/dl cholesterol at day 5 of differentiation did not affect the enucleation process but significantly increased recovery of enucleated cRBC following filtration over leukodepletion filters. The addition of cholesterol at day 5 increased the osmotic resistance of cRBC. In conclusion, cholesterol supplementation after the onset of enucleation improved the robustness of cRBC and increased the yield of enucleated cRBC in the purification process.

Coenzyme Q10 supplementation affects cellular ionic balance: relevance to aging.

Aging results into disruptive physiological functioning and cellular processes that affect the composition and structure of the plasma membrane. The plasma membrane is the major regulator of ionic homeostasis thatregulates the functioning of membrane transporters and exchangers. Coenzyme Q10 is a lipid-soluble antioxidant molecule that declines during aging and age-associated diseases. The presentstudy aims to explore the role of Coenzyme Q10 supplementation to rats during aging on membrane transporters and redox biomarkers. The studywas conducted on young and old male Wistar rats supplemented with 20 mg/kg b.w. of Coenzyme Q10 per day. After a period of 28days, rats were sacrificed and erythrocyte membrane was isolated. The result exhibits significant decline in biomarkers of oxidative stress in old control rats when compared with young control. The effect of Coenzyme Q10 supplementation was more pronounced in old rats. Thefunctioning of membrane transporters and Na+/H+ exchanger showed potential return to normal levels in the Coenzyme Q10 treated rats. Overall, the results demonstrate that Coenzyme Q10 plays an important role in maintaining redox balance in cells which interconnects with membrane integrity. Thus, Coenzyme Q10 supplementation may play animportant role in protecting age related alterations inerythrocyte membrane physiology.

Analysis and Quantification of the Mitochondrial-ER Lipidome.

Mitochondria are vital organelles essential for cellular functions, but their lipid composition and response to stressors are not fully understood. Recent advancements in lipidomics reveal insights into lipid functions, especially their roles in metabolic perturbations and diseases. Previous methods have focused on the protein composition of mitochondria and mitochondrial-associated membranes. The advantage of our technique is that it combines organelle isolation with targeted lipidomics, offering new insights into the composition and dynamics of these organelles in pathological conditions. We developed a mitochondria isolation protocol for L6 myotubes, enabling lipidomics analysis of specific organelles without interference from other cellular compartments. This approach offers a unique opportunity to dissect lipid dynamics within mitochondria and their associated ER compartments under cellular stress. Key features • Analysis and quantification of lipids in mitochondria-ER fraction through liquid chromatography-tandem mass spectrometry-based lipidomics (LC-MS/MS lipidomics). • LC-MS/MS lipidomics provide precise and unbiased information on the lipid composition in in vitro systems. • LC-MS/MS lipidomics facilitates the identification of lipid signatures in mammalian cells.

A novel Janus composite membrane and its enhanced antifouling strategy for emulsion purification

The development of advanced membranes for the efficient separation of oil-water emulsions and the degradation of soluble pollutants is crucial for environmental protection. This study presents a Janus composite membrane with Co(CO3)0.5OH·0.11H2O nanoneedle arrays, fabricated through electrospinning, membrane assembly, surface hydrophobization, and chemical bath deposition (CBD). By controlling the amount of carbon nanofiber (CNF) and CBD time, the membrane's morphology can be optimized for improved performance. In dead-end filtration driven by gravity, the membrane effectively separates stabilized oil-in-water emulsions and demonstrates strong anti-fouling capabilities. Furthermore, the membrane exhibits significant catalytic activation for peroxymonosulfate (PMS), enabling complete restoration of water flux of polluted membranes and purifying emulsions with soluble organic pollutants. To further enhance anti-fouling performance, a novel separation strategy integrating pulse current is proposed. Under the influence of a pulsed electric field, the membrane achieves a permeate flux nearly twice as high as that observed without this external stimulus, while maintaining high separation efficiency. This research advances Janus nanofiber membrane development via electrospinning techniques and supports sustainable treatment of oily wastewater.

Optimization of mass transfer-enhanced chlorine-resistant crosslinked PVA composite membranes for pervaporation desalination

Pervaporation (PV) is characterised by good hydrophilicity and antifouling properties. However, it is still unavoidable to need cleaning during long-term operation. Sodium hypochlorite (NaClO) is a commonly used purifying agent for organic pollutants, but it may cause damage to the polymer membrane. In this study, a grafting method was proposed to enhance the chlorine resistance and water permeability of membrane composite polyvinyl alcohol (PVA) pervaporation membrane. Modified PVA (SPVA) was prepared by grafting 5-sulfosalicylic acid (SSA) to improve the hydrophilicity of the membrane using the sulfonic acid group on SSA. SPVA-FA/PTFE composite membranes were prepared by using perfluoroglutaric acid (PFGA) as crosslinking agent to improve the chlorine resistance of the membranes by utilising the C-F chain contained therein. The water flux was 120.38 ± 1.72 kg/(m2·h), which was 84.2 % higher than that before grafting, when tested at 70 °C and 3.5 wt% NaCl. The chlorine resistance of SPVA-PFGA/PTFE composite membrane was tested in 2000 ppm (pH = 12) NaClO solution for 480 h, and the salt rejection remained above 99.93 %. When desalinating 20 wt% NaCl at 70 °C, the water flux of SPVA-PFGA/PTFE membrane is 51.95 ± 0.6 kg/(m2·h), which has the potential to treat high concentration brine.

Controlled Twill Surface Structure Endowing Nanofiber Composite Membrane Excellent Electromagnetic Interference Shielding

HighlightsInspired by the Chinese Knotting weave structure, an electromagnetic interference (EMI) nanofiber composite membrane with a twill surface was prepared.The EMI shielding efficiency (SE) of the composite membrane was 103.9 dB when the MXene/silver nanowires (MXene/AgNW) content was only 7.4 wt% and the surface twill structure improved the EMI by 38.5%.The nanofiber composite membrane demonstrated an excellent thermal management performance, hydrophobicity, non-flammability, and performance stability, which was demonstrated by an EMI SE of 97.3% in a high-temperature environment at 140 °C.

Green ammonia production via recycle membrane reactor: Experiment and process simulation

With the increasing demand for ammonia (NH3) and the environmental benefits, green and sustainable NH3 production has been urgently developed and is expected to replace the traditional Haber-Bosch (HB) process with high energy consumption and COx emission. In this work, a recycle membrane reactor (RMR) process where a catalytic reactor relates to a membrane separator in series and the retentate stream is recycled to the reactor was designed and executed to produce NH3, in which a Ru (10 wt%)/Cs/MgO catalyst and two membranes with different permeation properties and NH3 selectivity were used. By independently controlling the temperature of the reactor and membrane separator, the synthesized NH3 was selectively extracted from feed side to permeate side by Aquivion/ceramic composite and sulfonated (3-mercaptopropyl)trimethoxysilane membranes. Impressively, NH3 mole fraction was greatly increased from 0.01 of equilibrium state to 0.1–0.45 in permeate stream, which is ascribed to the permeation properties and NH3 selectivity of membrane at different temperatures. Moreover, a one-dimensional, isothermal, and plug-flow model was proposed to simulate RMR, which can be successfully applied to deeply understand the mechanism of RMR. Furthermore, a green NH3 production process based on RMR was simulated to give rationalized suggestions for the NH3 synthesis under mild conditions.