The performance of mixed-matrix membranes (MMMs) based on Matrimid® and benzimidazole-linked polymers (BILPs) have been investigated for the separation CO2/N2 and the dependency on the filler porosity. BILPs with two different porosities (BILP-101 and RT-BILP-101) were synthesized through controlling the initial polymerization rate and further characterized by several techniques (DRIFTs, 13C CP/MAS NMR, SEM, TEM, N2 and CO2 adsorption). To investigate the influence of porosity, the two types of fillers were incorporated into Matrimid® to prepare MMMs at varied loadings (8, 16 and 24 wt%). SEM confirmed that both BILP-101 and RT-BILP-101 are well dispered, indicating their good compatibility with the polymeric matrix. The partial pore blockage in the membrane was verified by CO2 adsorption isotherms on the prepared membranes. In the separation of CO2 from a 15:85 CO2:N2 mixture at 308 K, the incorporation of both BILPs fillers resulted in an enhancement in gas permeability together with constant selectivity owing to the fast transport pathways introduced by the porous network. It was noteworthy that the initial porosity of the filler had a large impact in separation permeability. The best improvement was achieved by 24 wt% RT-BILP-101 MMMs, for which the CO2 permeability increases up to 2.8-fold (from 9.6 to 27 Barrer) compared to the bare Matrimid®.@en

The use of an azine-linked covalent organic framework (ACOF-1) as filler in mixed-matrix membranes (MMMs) has been studied for the separation of CO2 from N2. To better understand the mechanisms that govern separation in complex composites, MMMs were prepared with different loadings of ACOF-1 and three different polymers as continuous phase: low flux-mid selectivity Matrimid®, mid flux-high selectivity Polyactive™ and high flux-low selectivity 6FDA:DAM. The homogeneous distribution of ACOF-1 together with the good adhesion between the ACOF-1 particles and the polymer matrices were confirmed by scanning electron microscopy. In mixed-gas CO2/N2 separation a clear influence of the polymer used was observed on the performance of the composite membranes. While for Matrimid® and 6FDA:DAM an overall enhancement of the polymer's separation properties could be achieved, in case of Polyactive™ penetration of the more flexible polymer into the COF porosity resulted in a decreased membrane permeability. The best improvement was obtained for Matrimid®-based MMMs, for which a selectivity increase from 29 to 35, together with an enhancement in permeability from 9.5 to 17.7 Barrer for 16 wt% COF loading, was observed. Our results demonstrate that the combination of the filler-polymeric matrix pair chosen is crucial. For a given filler the polymer performance improvement strongly depends on the polymeric matrix selected, where a good match between the discontinuous and continuous phase, both in the terms of compatibility and gas separation properties, is necessary to optimize membrane performance.@en

Membrane technology has attracted great industrial interest in carbon capture and separation owing to the merits of energy-efficiency, environmental friendliness and low capital investment. Conventional polymeric membranes for CO2 separation suffer from the trade-off between permeability and selectivity. Introducing porous fillers in polymers is one approach to enhance membrane separation performance. Metal-organic frameworks (MOFs), with ordered porous structure and diverse chemical functionalities, are promising fillers to prepare mixed matrix membranes (MMMs) for CO2 separation. However, the main issue of MOF based MMMs in industry is their stability and processability. This review analyses recent work on stable and scalable MOF based MMMs for CO2 separation. The typical stable MOFs, MOF-based MMMs and the scalable MOF synthesis are summarized. A large number of MOF-based MMM suffer from instability upon exposure to contaminants. For that reason, we also discuss the use of covalent organic frameworks (COFs) as an alternative to prepare MMMs for CO2 separation, considering their excellent stability and good compatibility with polymers. Finally, a brief conclusion and current challenges on obtaining scalable and stable MMMs are outlined. This review may provide some guidance for designing high performance MMMs for industrial CO2 capture and separation to help achieving carbon neutrality.@en

Increasing helium use in research and production processes necessitates separation techniques to secure sufficient supply of this noble gas. Energy-efficient helium production from natural gas is still a big challenge. Membrane gas separation technology could play an important role. Herein, a novel poly(p-phenylene benzobisimidazole) (PBDI) polymeric membrane for helium extraction from natural gas with low He abundance is reported. The membranes were fabricated by a facile interfacial polymerization at room temperature. The thin and defect-free membrane structure was manipulated by the confined polymerization of monomers diffusing through the interface between two immiscible liquids. Both He/CH4 selectivity and He permeance are competitive over those of other commercial perfluoropolymers. Even at low He content of 1%, separation performance of the PBDI membrane transcended the current upper bound. The unprecedented selectivity (>1000) together with the excellent stability (∼360 h) endows PBDI membranes with a great potential for energy-efficient industrial recovery and production of this precious He resources from reservoirs with low abundance.@en

The preparation and the performance of mixed matrix membranes based on metal-organic polyhedra (MOPs) are reported. MOP fillers can be dispersed as discrete molecular units (average 9 nm in diameter) when low filler cargos are used. In spite of the low doping amount (1.6 wt %), a large performance enhancement in permeability, aging resistance, and selectivity can be achieved. We rationalize this effect on the basis of the large surface to volume ratio of the filler, which leads to excellent dispersion at low concentrations and thus alters polymer packing. Although membranes based only on the polymer component age quickly with time, the performance of the resulting MOP-containing membranes meets the commercial target for postcombustion CO2 capture for more than 100 days.@en

Mixed-matrix membranes (MMMs) comprising Matrimid and a microporous azine-linked covalent organic frameworks (ACOF-1) were prepared and tested in the separation of CO2 from an equimolar CO2/CH4 mixture. The COF-based MMMs show a more than doubling of the CO2 permeability upon 16 wt % ACOF-1 loading together with a slight increase in selectivity compared to the bare polymer. These results show the potential of COFs in the preparation of MMMs.@en

High permeable and selective membranes are expected to be a promising alternative for low cost and energy efficient CO2 separation. However, the preparation and development of highly permeable and selective membranes are limited by the trade-off effect. Here, we prepared a stabilized high permeable and selective mixed matrix membrane based on the structural regulation of the NH2-functionalized Co/ZIF-8 heterometallic nanoparticles (NH2-Co/ZIF-8). The NH2-Co/ZIF-8 can be homogeneously dispersed in the polymer via chelation of the ester group and the metal node in the methacrylate-terminated PEO and the acrylate-terminated PEO. The amphiphilic interaction between the polymer and NH2-Co/ZIF-8 significantly increased the CO2 solubility resulting in the boost of both CO2 permeability and CO2/N2 selectivity. The best performance membrane exhibits a CO2 permeability of 2916 Barrer and a CO2/N2 selectivity of 47, surpassing the Robeson's upper bond (2008) by a wide margin.@en

High permeable and selective membranes are expected to be a promising alternative for low cost and energy efficient CO2 separation. However, the preparation and development of highly permeable and selective membranes are limited by the trade-off effect. Here, we prepared a stabilized high permeable and selective mixed matrix membrane based on the structural regulation of the NH2-functionalized Co/ZIF-8 heterometallic nanoparticles (NH2-Co/ZIF-8). The NH2-Co/ZIF-8 can be homogeneously dispersed in the polymer via chelation of the ester group and the metal node in the methacrylate-terminated PEO and the acrylate-terminated PEO. The amphiphilic interaction between the polymer and NH2-Co/ZIF-8 significantly increased the CO2 solubility resulting in the boost of both CO2 permeability and CO2/N2 selectivity. The best performance membrane exhibits a CO2 permeability of 2916 Barrer and a CO2/N2 selectivity of 47, surpassing the Robeson's upper bond (2008) by a wide margin.@en

High permeable and selective membranes are expected to be a promising alternative for low cost and energy efficient CO2 separation. However, the preparation and development of highly permeable and selective membranes are limited by the trade-off effect. Here, we prepared a stabilized high permeable and selective mixed matrix membrane based on the structural regulation of the NH2-functionalized Co/ZIF-8 heterometallic nanoparticles (NH2-Co/ZIF-8). The NH2-Co/ZIF-8 can be homogeneously dispersed in the polymer via chelation of the ester group and the metal node in the methacrylate-terminated PEO and the acrylate-terminated PEO. The amphiphilic interaction between the polymer and NH2-Co/ZIF-8 significantly increased the CO2 solubility resulting in the boost of both CO2 permeability and CO2/N2 selectivity. The best performance membrane exhibits a CO2 permeability of 2916 Barrer and a CO2/N2 selectivity of 47, surpassing the Robeson's upper bond (2008) by a wide margin.@en

High permeable and selective membranes are expected to be a promising alternative for low cost and energy efficient CO2 separation. However, the preparation and development of highly permeable and selective membranes are limited by the trade-off effect. Here, we prepared a stabilized high permeable and selective mixed matrix membrane based on the structural regulation of the NH2-functionalized Co/ZIF-8 heterometallic nanoparticles (NH2-Co/ZIF-8). The NH2-Co/ZIF-8 can be homogeneously dispersed in the polymer via chelation of the ester group and the metal node in the methacrylate-terminated PEO and the acrylate-terminated PEO. The amphiphilic interaction between the polymer and NH2-Co/ZIF-8 significantly increased the CO2 solubility resulting in the boost of both CO2 permeability and CO2/N2 selectivity. The best performance membrane exhibits a CO2 permeability of 2916 Barrer and a CO2/N2 selectivity of 47, surpassing the Robeson's upper bond (2008) by a wide margin.@en

High permeable and selective membranes are expected to be a promising alternative for low cost and energy efficient CO2 separation. However, the preparation and development of highly permeable and selective membranes are limited by the trade-off effect. Here, we prepared a stabilized high permeable and selective mixed matrix membrane based on the structural regulation of the NH2-functionalized Co/ZIF-8 heterometallic nanoparticles (NH2-Co/ZIF-8). The NH2-Co/ZIF-8 can be homogeneously dispersed in the polymer via chelation of the ester group and the metal node in the methacrylate-terminated PEO and the acrylate-terminated PEO. The amphiphilic interaction between the polymer and NH2-Co/ZIF-8 significantly increased the CO2 solubility resulting in the boost of both CO2 permeability and CO2/N2 selectivity. The best performance membrane exhibits a CO2 permeability of 2916 Barrer and a CO2/N2 selectivity of 47, surpassing the Robeson's upper bond (2008) by a wide margin.@en

High permeable and selective membranes are expected to be a promising alternative for low cost and energy efficient CO2 separation. However, the preparation and development of highly permeable and selective membranes are limited by the trade-off effect. Here, we prepared a stabilized high permeable and selective mixed matrix membrane based on the structural regulation of the NH2-functionalized Co/ZIF-8 heterometallic nanoparticles (NH2-Co/ZIF-8). The NH2-Co/ZIF-8 can be homogeneously dispersed in the polymer via chelation of the ester group and the metal node in the methacrylate-terminated PEO and the acrylate-terminated PEO. The amphiphilic interaction between the polymer and NH2-Co/ZIF-8 significantly increased the CO2 solubility resulting in the boost of both CO2 permeability and CO2/N2 selectivity. The best performance membrane exhibits a CO2 permeability of 2916 Barrer and a CO2/N2 selectivity of 47, surpassing the Robeson's upper bond (2008) by a wide margin.@en

We demonstrate that b-oriented MFI (Mobil Five) zeolite membranes can be manufactured by in situ crystallization using an intermediate amorphous SiO2 layer. The improved in-plane growth by using a zeolite growth modifier leads to fusion of independent crystals and eliminates boundary gaps, giving good selectivity in the separation of CO2/Xe mixtures. The fast diffusion of CO2 dominates the overall membrane selectivity toward the CO2/Xe mixture. Because of the straight and short [010] channels, the obtained CO2 permeation fluxes are several orders of magnitude higher than those of carbon molecular sieving membranes and polymeric membranes, opening opportunities for Xe recovery from waste anesthetic gas.@en

We demonstrate that b-oriented MFI (Mobil Five) zeolite membranes can be manufactured by in situ crystallization using an intermediate amorphous SiO2 layer. The improved in-plane growth by using a zeolite growth modifier leads to fusion of independent crystals and eliminates boundary gaps, giving good selectivity in the separation of CO2/Xe mixtures. The fast diffusion of CO2 dominates the overall membrane selectivity toward the CO2/Xe mixture. Because of the straight and short [010] channels, the obtained CO2 permeation fluxes are several orders of magnitude higher than those of carbon molecular sieving membranes and polymeric membranes, opening opportunities for Xe recovery from waste anesthetic gas.@en

It is demonstrated that moderate oxygen vacancies can greatly improve the photo-responsive performance of Zinc oxide (ZnO) nanoparticles thin film/p-Si heterojunctions. The ZnO nanoparticles thin film/p-Si heterojunctions shows a stable, repeatable photo response at 365 nm or 900 nm. Under 900 nm of 0.1 mWcm −2 the sensitivity of device reaches an excellent value of 1.2 × 10 6 cm 2 /W, with outstanding detectivity of 3.6 × 10 12 cmHz 1/2 W −1 and ultrahigh responsivity of 3.5 AW -1 at −2 V, and a fast response speed with rising time (∼ms). The comprehensive properties of present device are significantly better than those reported ZnO thick film/Si heterojunctions and even compared with that of some new 2D nanomaterials/Si heterojunctions in all aspects of performance, achieving an optimal balance among all the critical features. The excellent performance of ZnO nanoparticles thin film/p-Si heterojunctions may be attributed to rising Fermi level of ZnO nanoparticles thin film due to moderate oxygen vacancies, the excellent optical absorption characteristics of ZnO nanoparticles thin film and the interface effect between ZnO nanoparticles thin film and Si. This high-performance heterojunctions photodetector should have important prospects for practical applications, and the integration of such metal oxide nanostructures with traditional Si semiconductor would open up great opportunities for next-generation optoelectronic devices. @en

It is demonstrated that moderate oxygen vacancies can greatly improve the photo-responsive performance of Zinc oxide (ZnO) nanoparticles thin film/p-Si heterojunctions. The ZnO nanoparticles thin film/p-Si heterojunctions shows a stable, repeatable photo response at 365 nm or 900 nm. Under 900 nm of 0.1 mWcm −2 the sensitivity of device reaches an excellent value of 1.2 × 10 6 cm 2 /W, with outstanding detectivity of 3.6 × 10 12 cmHz 1/2 W −1 and ultrahigh responsivity of 3.5 AW -1 at −2 V, and a fast response speed with rising time (∼ms). The comprehensive properties of present device are significantly better than those reported ZnO thick film/Si heterojunctions and even compared with that of some new 2D nanomaterials/Si heterojunctions in all aspects of performance, achieving an optimal balance among all the critical features. The excellent performance of ZnO nanoparticles thin film/p-Si heterojunctions may be attributed to rising Fermi level of ZnO nanoparticles thin film due to moderate oxygen vacancies, the excellent optical absorption characteristics of ZnO nanoparticles thin film and the interface effect between ZnO nanoparticles thin film and Si. This high-performance heterojunctions photodetector should have important prospects for practical applications, and the integration of such metal oxide nanostructures with traditional Si semiconductor would open up great opportunities for next-generation optoelectronic devices. @en

It is demonstrated that moderate oxygen vacancies can greatly improve the photo-responsive performance of Zinc oxide (ZnO) nanoparticles thin film/p-Si heterojunctions. The ZnO nanoparticles thin film/p-Si heterojunctions shows a stable, repeatable photo response at 365 nm or 900 nm. Under 900 nm of 0.1 mWcm −2 the sensitivity of device reaches an excellent value of 1.2 × 10 6 cm 2 /W, with outstanding detectivity of 3.6 × 10 12 cmHz 1/2 W −1 and ultrahigh responsivity of 3.5 AW -1 at −2 V, and a fast response speed with rising time (∼ms). The comprehensive properties of present device are significantly better than those reported ZnO thick film/Si heterojunctions and even compared with that of some new 2D nanomaterials/Si heterojunctions in all aspects of performance, achieving an optimal balance among all the critical features. The excellent performance of ZnO nanoparticles thin film/p-Si heterojunctions may be attributed to rising Fermi level of ZnO nanoparticles thin film due to moderate oxygen vacancies, the excellent optical absorption characteristics of ZnO nanoparticles thin film and the interface effect between ZnO nanoparticles thin film and Si. This high-performance heterojunctions photodetector should have important prospects for practical applications, and the integration of such metal oxide nanostructures with traditional Si semiconductor would open up great opportunities for next-generation optoelectronic devices. @en

It is demonstrated that moderate oxygen vacancies can greatly improve the photo-responsive performance of Zinc oxide (ZnO) nanoparticles thin film/p-Si heterojunctions. The ZnO nanoparticles thin film/p-Si heterojunctions shows a stable, repeatable photo response at 365 nm or 900 nm. Under 900 nm of 0.1 mWcm −2 the sensitivity of device reaches an excellent value of 1.2 × 10 6 cm 2 /W, with outstanding detectivity of 3.6 × 10 12 cmHz 1/2 W −1 and ultrahigh responsivity of 3.5 AW -1 at −2 V, and a fast response speed with rising time (∼ms). The comprehensive properties of present device are significantly better than those reported ZnO thick film/Si heterojunctions and even compared with that of some new 2D nanomaterials/Si heterojunctions in all aspects of performance, achieving an optimal balance among all the critical features. The excellent performance of ZnO nanoparticles thin film/p-Si heterojunctions may be attributed to rising Fermi level of ZnO nanoparticles thin film due to moderate oxygen vacancies, the excellent optical absorption characteristics of ZnO nanoparticles thin film and the interface effect between ZnO nanoparticles thin film and Si. This high-performance heterojunctions photodetector should have important prospects for practical applications, and the integration of such metal oxide nanostructures with traditional Si semiconductor would open up great opportunities for next-generation optoelectronic devices. @en

It is demonstrated that moderate oxygen vacancies can greatly improve the photo-responsive performance of Zinc oxide (ZnO) nanoparticles thin film/p-Si heterojunctions. The ZnO nanoparticles thin film/p-Si heterojunctions shows a stable, repeatable photo response at 365 nm or 900 nm. Under 900 nm of 0.1 mWcm −2 the sensitivity of device reaches an excellent value of 1.2 × 10 6 cm 2 /W, with outstanding detectivity of 3.6 × 10 12 cmHz 1/2 W −1 and ultrahigh responsivity of 3.5 AW -1 at −2 V, and a fast response speed with rising time (∼ms). The comprehensive properties of present device are significantly better than those reported ZnO thick film/Si heterojunctions and even compared with that of some new 2D nanomaterials/Si heterojunctions in all aspects of performance, achieving an optimal balance among all the critical features. The excellent performance of ZnO nanoparticles thin film/p-Si heterojunctions may be attributed to rising Fermi level of ZnO nanoparticles thin film due to moderate oxygen vacancies, the excellent optical absorption characteristics of ZnO nanoparticles thin film and the interface effect between ZnO nanoparticles thin film and Si. This high-performance heterojunctions photodetector should have important prospects for practical applications, and the integration of such metal oxide nanostructures with traditional Si semiconductor would open up great opportunities for next-generation optoelectronic devices. @en

It is demonstrated that moderate oxygen vacancies can greatly improve the photo-responsive performance of Zinc oxide (ZnO) nanoparticles thin film/p-Si heterojunctions. The ZnO nanoparticles thin film/p-Si heterojunctions shows a stable, repeatable photo response at 365 nm or 900 nm. Under 900 nm of 0.1 mWcm −2 the sensitivity of device reaches an excellent value of 1.2 × 10 6 cm 2 /W, with outstanding detectivity of 3.6 × 10 12 cmHz 1/2 W −1 and ultrahigh responsivity of 3.5 AW -1 at −2 V, and a fast response speed with rising time (∼ms). The comprehensive properties of present device are significantly better than those reported ZnO thick film/Si heterojunctions and even compared with that of some new 2D nanomaterials/Si heterojunctions in all aspects of performance, achieving an optimal balance among all the critical features. The excellent performance of ZnO nanoparticles thin film/p-Si heterojunctions may be attributed to rising Fermi level of ZnO nanoparticles thin film due to moderate oxygen vacancies, the excellent optical absorption characteristics of ZnO nanoparticles thin film and the interface effect between ZnO nanoparticles thin film and Si. This high-performance heterojunctions photodetector should have important prospects for practical applications, and the integration of such metal oxide nanostructures with traditional Si semiconductor would open up great opportunities for next-generation optoelectronic devices. @en