Porous Carbon Membranes Research Articles

Emerging contaminants removal through fluorine-doped carbon hollow fiber microfiltration membrane based on metal-free electro-Fenton

The emerging contaminants with high toxicity and bioaccumulation potentially threaten to human health, which was difficult removed by traditional biological treatment or membrane separation. In view of this, a novel type of fluorine (F)-doped carbon hollow fiber microfiltration membrane was prepared for realizing emerging contaminants removal through metal-free electro-Fenton. Herein, polyaniline (PANI) was used as a precursor for preparation of porous carbon membrane. The graphitic N and pyridinic N on porous carbon were used as the active sites for H2O2 production and its further activation to ·OH, which realized metal-free electro-Fenton reaction. According to the results, the carbon nanotubes with F-PANI at the ratio of 1:1 and calcination temperature at 300 °C endowed the membrane moderate resistance and pure water permeability of 430 Ω and 48.51 L/(m2 h bar), respectively. Importantly, the intensity of ·OH generation was further significant enhanced by introducing C–F bonding into the membrane. Therefore, the bisphenol A (BPA), sulfamethoxazole (SMZ) and atrazine (ATZ) removal rates were 92.63 %, 38.47 % and 27.05 %, respectively. For control group without bias, the removal rates of above contaminants were 0 % removal rates. Moreover, the membrane permeate loss by filtrating BPA, SMZ and ATZ were 0.13, 0.15 and 0.05, which were 0.20, 0.24 and 0.21 for control group.

Electro-Fenton enhanced MBR for fouling alleviation based on MIL-88B-Fe derived carbon membrane with in-situ generated [rad]OH

Porous carbon membrane (PCM) derived from MIL-88B-Fe with the ability of in-situ generation of hydroxyl radical was introduced to electro-enhanced aerobic membrane bioreactor (EMBR) for membrane fouling mitigation and wastewater quality improvement. The resultant PCM obtained with the calcination temperature of 1000 °C owned significant enhancement on hydrophilic and conductive properties, which helped PCM under −1.2 V could completely remove 10 mg/L bovine serum albumin with 2.5 % membrane flux loss rate. During the 76-day operation of EMBR, the extracellular polymeric substances could be suppressed for depositing on the −1.2 V enhanced PCM due to the combined effect of electrostatic barrier and OH oxidation. The pollutant intensity of total cells, polysaccharides and proteins were all reduced on PCM with −1.2 V. After operation, 36.0 % of cake layer pores was blocked in EMBR by total cells, polysaccharides and proteins. However, it was accounted for 69.8 % of the control group. Above results explained why the EMBR owned an always lower transmembrane pressure. Meanwhile, the pollutants removal rates of COD and NH4+-N were as high as 95 % and 98 % with electro-enhanced filtration, respectively, which is attributed to the collaborated effect from electrochemical effect and significantly increased microbial species related to organic pollutants removal, such as Azohydromonas, Thermomonas.

Oxidation two-dimensional porous carbon membrane for efficient and precise separation of mixed dyes solution

In actual production, dye wastewater typically contains a mixture of two or more dyes. Therefore, developing efficient and precise separation techniques for mixed dyes solution is of great value but still faces great challenges. In this study, we prepared two-dimensional porous carbon sheets (PCS) using Ti3C2 as the precursor through halogenation etching technology. Subsequently, the PCS was oxidized with nitric acid at room temperature to obtain oxidized porous carbon sheets (OPCS). When mixed dyes solution RB/MO and RB/MB were screened using OPCS vacuum filtration self-assembled porous carbon membrane (OPCSM), the rejection rate for the larger dye RB was 99.9 %, while the permeation rates for the smaller dyes MO and MB were 91.0 % and 99.5 %, respectively. Notably, OPCSM also exhibited much higher water flux than the previously reported. The combination of high water flux and precise screening make OPCSM a highly promising membrane for the separation and reuse of mixed dyes.

Boosting Electrochemical CO2 Reduction to CO by Regulating the Porous Structure of Carbon Membrane.

Ni single-atom-decorated nitrogen-doped carbon materials (Ni-Nx-C) have demonstrated high efficiency in the electrochemical reduction of CO2 (CO2RR) to CO. In this study, Ni-Nx-C active sites were embedded within a carbon membrane via an electrospinning and pyrolysis process. The resulting self-supported carbon membrane hosting Ni-Nx-C sites could be directly utilized as an electrode for the CO2RR. To enhance the CO2RR performance of the carbon membrane, the porous structure of the carbon membrane was fine-tuned by incorporating a pore-forming agent. The optimized porous carbon membrane electrode, K0.66-Ni-NC, achieved an impressive CO faradaic efficiency (FECO) of over 90% within a wide potential range from -0.8 to -1.6 V vs RHE for CO2RR. Additionally, it maintained an FECO of above 90% at -0.8 V vs RHE throughout a 30 h durability test in an H-cell. Further analysis has revealed that the porous structure of the carbon membrane not only facilitates the mass transport of CO2 but also increases the level of exposure of active sites during the CO2RR.

Transition Metal‐Cross‐Linked‐Starch Aerogel‐Derived Porous Carbon‐Based Monolithic Chainmail Electrodes for High‐Current‐Density and Durable Alkaline Water Splitting

AbstractA porous carbon‐based monolithic chainmail electrode, namely Co2P@CSA, is fabricated via direct carbonization of Co2+‐cross‐linked‐starch aerogel (Co2+‐SA) followed by low‐temperature vapor phosphorization. During successive carbonization‐phosphorization, the SA framework is formulated into 3D hierarchically porous carbon membrane matrix comprising hollow open carbon microspheres while the cross‐linked Co species are converted into uniformly distributed carbon‐encapsulated Co2P nanoparticles on carbon microspheres. Thanks to the high porosity, excellent electrolyte wettability, unique chainmail structure, and good mechanical strength, the monolithic Co2P@CSA can be directly used as a binder‐free bifunctional electrocatalyst for alkaline water splitting, and it can afford a high current density of 100 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at low overpotentials of 140.0 and 305.5 mV, respectively, with outstanding stability at 50 mA cm−2 for >30 h. More significantly, an alkaline electrolyzer assembled using Co2P@CSA achieves a current density of 100 mA cm−2 for overall water splitting (OWS) at a cell voltage of 1.94 V with unit Faradaic efficiency and provides a high solar‐to‐hydrogen (STH) conversion efficiency of 13.4 % when driven by a commercial silicon solar cell. This work offers an effective strategy towards cost‐effective fabrication of high‐performance carbon‐based monolithic chainmail electrocatalysts for energy conversion reactions.

A self-phosphorized carbon-based monolithic chainmail electrode for high-current-density and durable alkaline water splitting

A monolithic chainmail electrode is developed by embedding self-phosphorized carbon-coated Co2P nanoparticles within a porous carbon membrane, exhibiting excellent activity and durability for both alkaline HER and OER at high current densities.

On assessing the carbon capture performance of graphynes with particle swarm optimization.

Tackling climate change is one of the greatest challenges of current times and therefore the development of efficient technologies to limit anthropogenic emissions is of utmost urgency. Recent research towards this goal has alluded to the use of carbon-based solid sorbents for carbon capture. Graphynes (GYs), an interesting class of porous carbon membranes, have recently proven their potential as excellent membranes for gas adsorption and separation. Herein, we explored the CO2 and N2 adsorption characteristics and CO2/N2 selectivities of a class of GYs, namely γ-GY-1, γ-GY-2 and γ-GY-4. We investigated the putative global minimum geometries of adsorbed unary (n = 2-10) and binary (n : m; n, m ∈ [1, 8]) clusters of CO2 and N2 by employing a stochastic global optimization method called particle swarm optimization in conjunction with empirical intermolecular force field formulations. The intervening interactions are modeled using various pairwise potentials, including Lennard-Jones potential, improved Lennard-Jones potential, Buckingham potential and Coulombic potential. The binding energies for both unary and binary clusters are highest for adsorption on γ-GY-1, followed by γ-GY-2. The putative global minimum geometries suggested that N2 molecules preferred binding over the pore centres while CO2 molecules showed higher clustering propensity than any binding site preference. The predicted interaction energies suggested higher selectivity for CO2 over N2 for all the three γ-GYs.

Polyamide-imide copolymer-derived carbon molecular sieve membranes for efficient hydrogen/carbon dioxide separation

Carbon molecular sieve (CMS) membranes are emerging porous carbon membranes for chemical separation and purification. Polyamide-imide (PAI) copolymers have shown attractive separation performance for natural gas upgrading and organic solvent separations. However, PAIs are rarely used as precursors to derive CMS membranes. This work shows that CMS hollow fiber membranes made from a PAI (Torlon®) can provide highly competitive H2 permeability and H2/CO2 selectivity overcoming the 2008 Robeson upper bound under both single-gas and mixed-gas permeation. With imide and amide moieties, the PAI showed intermediate H2/CO2 separation performance between a polyimide (PI) and a polyaramid (PA). Interestingly, the trend was translated to the CMS membranes, i.e., the PAI-derived CMS membrane showed intermediate H2/CO2 separation performance between the PI-derived CMS membrane and PA-derived CMS membrane with an excellent balance of H2 permeability and H2/CO2 selectivity. Sorption studies indicate that the PAI-derived CMS membrane had intermediate H2 diffusivity and H2/CO2 diffusion selectivity, which was further attributed to its intermediate ultramicropore size. To our best knowledge, this was the first report of PAI-derived CMS hollow fiber membranes with competitive gas separation performance and the first investigation of the chemistry and pore structure of PAI-derived porous carbon. This study also underscores the role of precursor backbone chemistry in tailoring CMS membrane properties, further suggesting that CMS membranes derived from copolymers comprising mixed backbone chemistry can give simultaneously attractive permeability and selectivity.

Facile and sustainable synthesis of sugarcane-derived binderless self-supported porous carbon membrane for advanced electrode materials

Powder biomass-derived electrodes have been extensively explored and used in capacitor devices, but there are still problems in practice, such as complicated electrode assembly processes and insufficient capacitance with larger current density. We proposed an advanced approach for producing porous carbon membranes derived from sugarcane that could be directly mounted as flexible binderless self-supported electrodes. A sugarcane-derived porous carbon membrane (SPCM) was simply prepared by freeze-drying followed and carbonization with KOH as an activator. The specific surface area of SPCM was 459.5 m² g−1, and the main elements were N (2.05 at%), O (21.45 at%), and C (73.62 at%). Compared with other biomass materials, it possessed a highly porous, multi-level structure and contained abundant nitrogen and oxygen functional groups, which facilitate ion adsorption and rapid electron transfer. Consequently, the symmetrical SPCM electrodes exhibit favorable electrochemical characteristics, at a current density of 0.5 A g−1, the specific capacitance measured at 248.0 F g−1. Additionally, the energy density reached 8.6 Wh kg−1 at a power density of 83.3 W kg−1, and the power density of 1666.7 W kg−1 was attained at an energy density of 1.9 Wh kg−1.

Facile Fabrication of Wood-Derived Porous Fe3C/Nitrogen-Doped Carbon Membrane for Colorimetric Sensing of Ascorbic Acid.

Fe3C nanoparticles hold promise as catalysts and nanozymes, but their low activity and complex preparation have hindered their use. Herein, this study presents a synthetic alternative toward efficient, durable, and recyclable, Fe3C-nanoparticle-encapsulated nitrogen-doped hierarchically porous carbon membranes (Fe3C/N-C). By employing a simple one-step synthetic method, we utilized wood as a renewable and environmentally friendly carbon precursor, coupled with poly(ionic liquids) as a nitrogen and iron source. This innovative strategy offers sustainable, high-performance catalysts with improved stability and reusability. The Fe3C/N-C exhibits an outstanding peroxidase-like catalytic activity toward the oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of hydrogen peroxide, which stems from well-dispersed, small Fe3C nanoparticles jointly with the structurally unique micro-/macroporous N-C membrane. Owing to the remarkable catalytic activity for mimicking peroxidase, an efficient and sensitive colorimetric method for detecting ascorbic acid over a broad concentration range with a low limit of detection (~2.64 µM), as well as superior selectivity, and anti-interference capability has been developed. This study offers a widely adaptable and sustainable way to synthesize an Fe3C/N-C membrane as an easy-to-handle, convenient, and recoverable biomimetic enzyme with excellent catalytic performance, providing a convenient and sensitive colorimetric technique for potential applications in medicine, biosensing, and environmental fields.

S, N co-doped carbon material functionalized catalytic membrane for efficient peroxymonosulfate activation and continuous refractory pollutants flow-treatment

Peroxymonosulfate (PMS) coupled with membrane technology shows great potential for refractory pollutants treatment. A simple method was developed to construct a highly efficient catalytic system consisting of S, N co-doped porous carbon (SNC) and polyvinylidene fluoride (PVDF) catalytic membrane. The degradation efficiency of tetracycline hydrochloride achieved a minimum of 91 %. The introduction of N and S dopants improved the defect density of the catalytic membrane, with graphite-N promoting PMS activation to generate 1O2, and thiophene S might be consumed or converted into oxidation-S as an active site during TC degradation. Loading SNC onto the PVDF membrane significantly enhanced its anti-pollution performance. The SNC/PVDF active catalytic membrane exhibited excellent degradation performance for various pollutants, maintaining an efficiency of approximately 80 % even after continuous degradation for 360 min. This work presents a novel catalytic membrane design that offers a promising approach to effectively treat refractory pollutants in wastewater.

Fabrication of flexible nitrogen and phosphorus-codoped porous carbon membrane and investigation of capacitance performance

Porous carbon materials have been used extensively in new energy storage materials. They have the advantages of high stability, large specific surface area, and good electrical conductivity. However, carbon material capacitance still needs to be increased. In this paper, nitrogen and phosphorus-codoped porous carbon membrane (NPCM) was prepared by electrostatic spinning using polyacrylonitrile (PAN) as a carbon and nitrogen source, triphenylphosphine (TPP) as a phosphorus source and SBA-15 as a templating agent. When PAN/TPP was set to 2:1, the resulting NPCM has good flexibility, with N and P doping content of 13.8% and 0.5%, respectively, and a specific surface area of 872 m2/g. The NPCM was used as the working electrode with 1.0 M H2SO4 electrolyte and a specific capacitance of 215 F/g was achieved at a current density of 0.5 A/g by a three-electrode test, The capacitance retention rate could reach 103% after 1000 charge/discharge cycles at a current density of 2.0 A/g. Therefore, these results indicate that NPCM has great potential for application in high-performance flexible supercapacitors.

In-situ generated Co2P nanoparticle-embedded porous carbon membrane as an advanced hybrid electrode for high-areal-capacitance supercapacitors

Hybridizing powdery carbons with transition metal phosphides (TMPs) can effectively address the issues of sluggish kinetics and volume expansion associated with TMPs in supercapacitors (SCs). However, the practical use of powdery TMPs/carbon materials in SCs is limited by tedious electrode preparation process, unfavorable performance, and inferior cycling stability. Herein, we develop carbon membrane-based hybrid electrodes (Co2P@CTF) by the direct carbonization of Co-containing tofu (TF) aerogel prepared by coagulating soybean proteins using Co2+ ions. During carbonization, the cross-linked protein frameworks were transformed into a porous, mechanically strong, and conductive carbon matrix, whereas the Co species were in situ self-phosphorized to be highly dispersed carbon-coated Co2P nanoparticles without using external phosphorus sources. The best Co2P@CTF electrode (Co2P@CTF-1000) demonstrates a high areal capacitance (Ca) of 2.44 F cm−2 at 1.0 mA cm−2. Moreover, a symmetric SC assembled with Co2P@CTF-1000 deliveries a Ca of 1.33 F cm−2 at 1.0 mA cm−2, achieves an energy density of 90 μWh cm−2 at a power density of 699.4 μW cm−2, and retains a 104.8% capacitance with a nearly unit coulomb efficiency at 10 mA cm−2 after 50000 cycles. This study offers an effective strategy towards carbon membrane-supported TMPs hybrid electrodes based on the direct self-phosphorization mechanism for the practical applications in SCs.

Poly (Ionic Liquid)-Metal Organic Framework-Derived Nanoporous Carbon Membranes: Facile Fabrication and Ultrahigh Areal Capacitance.

With the rapid development of energy storage technology, the operation of portable and wearable devices is inseparable from high energy density power supplies. However, the demand for high performance supercapacitors in movable smart electronics is still restrained by their insufficient areal capacitance and limited power/energy densities. In addition, some electroactive materials, including metal oxides, conductive polymers, graphene, porous carbons, etc., are inevitable to use extra adhesives for the preparation of electrode materials. In this work, integrated hierarchical graphitic porous carbon membranes used as the electrodes without adhesives are successfully synthesized, via pyrolyzing poly(ionic liquid)s (PILs)-metal organic frameworks (MOFs) composite membranes. The asymmetric supercapacitor is assembled by the carbonized PIL-MOF composite membrane and PILs-derived porous carbon membrane, and exhibits significant areal capacitance with remarkable power and energy densities. In the two-electrode system, the areal capacitance can reach 9.5F cm-2 with an energy density of 1.91mWh cm-2 . In the fabricated all-solid-state supercapacitors, the areal capacitance and energy density achieved 3.2F cm-2 and 0.65mWh cm-2 , respectively, exceeding most reported ones. Therefore, the integrated carbon membrane electrodes with high areal capacitance reveal great potential in miniaturized devices, and further show a wider application scope through regulating PILs.

A porous carbon membrane with abundant intrinsic carbon defects as an integrated gas-diffusion electrode for CO2 electroreduction

A highly defective porous carbon membrane (HDPCM) is developed via CO2 thermal etching, which exhibits high efficiency for electrocatalytic CO2-to-CO conversion and can be formulated into an integrated gas-diffusion electrode for direct use in a flow cell.

Preparation and performance of electrocatalytic carbon membranes for treating micro-polluted water

Porous carbon membranes (PCMs) with three functions of adsorption, electrocatalytic oxidation and membrane filtration were prepared from coconut shell activated carbon using carboxymethyl cellulose (CMC, 10 wt%) and benzoxazine resin (BR, 10 wt%-40 wt%) as the binder components. The morphology and microstructure of PCMs were characterized by SEM, XRD, Raman and nitrogen adsorption. An electrocatalytic membrane reactor (ECMR) was constructed using PCMs as the anode materials to investigate their water treatment performance. Results show that the PCMs have well-developed hierarchical macro, meso and micropores, whose macropore size decreases with the particle size of the activated carbon. The mechanical strength and electrical conductivity of the PCMs increased with BR content and carbonization temperature. The water flux decreased as the average particle size of the activated carbon decreased and the iodine value decreased with decreasing BR content. The PCM performed best with an excellent comprehensive performance in adsorption, electrocatalytic oxidation and filtration when it was prepared from an activated carbon of average particle size of 37.9 μm using a BR content of 30 wt% and a carbonization temperature of 950 °C. For the micro-polluted Lingshui River water in Dalian, the removal of COD, UV254, turbidity and bacteria with the ECMR reached 94.3%, 90.5%, 96.3% and 100%, respectively, and heavy metal ions (Pb2+, Cu2+, Zn2+, Ni2+) were removed to levels below the detection limits, and the anti-fouling performance was good. The excellent performance in treating micro-polluted water is ascribed to the combined effects of adsorption, electrocatalytic oxidation and filtration.

Flexible carbon membrane supercapacitor based on γ-cyclodextrin-MOF

Supercapacitors (SCs) with high energy density and power density are a research hotspot. Herein, we report a flexible porous carbon membrane supercapacitor prepared by electrospinning polyacrylonitrile (PAN) with γ-cyclodextrin-MOF (γ-CD-MOF) and then carbonizing at 900 °C. BET results showed that the supercapacitor retained the skeleton of γ-CD, γ-CD-MOF and the pores formed by the spun-fibers, which were 0.73, 1.09 and 23–186 nm, respectively, showing a high specific surface area of 134.7 m2/g. The hierarchically porous structures ensure rapid charge transfer and ion diffusion, resulting in the PAN/γ-CD-MOF carbon electrode with a high capacity of 283.3 F/g. Moreover, the supercapacitor had a high energy density up to 17.5 Wh/kg and power density up to 6 kW/kg. Significantly, it showed excellent cycle stability with a capacitance retention of 97.5% after 6000 cycles. This work provides a supramolecular strategy to construct a flexible porous carbon membrane, which has potential for supercapacitor applications.

Recycling decoration wastes toward a high-performance porous carbon membrane electrode for supercapacitive energy storage devices

A porous carbon membrane (DWCM) is facilely fabricated by direct carbonization of decoration waste using KOH as an activator and employed as a self-supported electrode for an aqueous supercapacitor (SC) with a superior capacitive performance.

Study on CO2 Adsorption and Permeance of Porous Carbon and Nitrogen Membranes Co-regulated by Charge and Strain

In order to capture and separate CO2 effectively, a novel method of controlling gas permeance by charge and strain is proposed, which has the superiority of controlled dynamic. The effects of porous C9N7 nanosheets on CO2 capture and permeability under different charge quantities and strains were analysed by molecular dynamics (MD) simulations and first-principles density function (DFT) calculations. The molecular permeability of CO2 can be as high as 5.9 × 107 GPU (CO2/CH4 separation) through 5 e- charge regulation. In addition, CO2 permeability increased with the increase of tensile strain, and the maximum permeability of 9% stretched C9N7 membrane is 3.6 × 107 GPU. On this basis, the method of combining negative charge and tensile strain was adopted to study the synergic effect. Under the condition of negative charge of 1 e- and tensile strain of 3%, CO2 permeability (CO2/CH4 separation) reached 3.2 × 107 GPU, which was 8 times of CO2 permeability when only 3% strain was added and 9 times of CO2 permeability when only 1 e- was added. Additionally, under the circumstance of negative charge of 5 e-, the CO2 obtained extra electrons -0.0666 e compared with natural C9N7 membrane. These results provide theoretical guidance for the development of highly controllable materials with CO2 capture and separation.

Electrochemical reduction of nitrate in a catalytic carbon membrane nano-reactor

Nitrate pollution is a critical environmental issue in need of urgent addressing. Electrochemical reduction is an attractive strategy for treating nitrate due to the environmental friendliness. However, it is still a challenge to achieve the simultaneous high activity and selectivity. Here we report the design of a porous tubular carbon membrane as the electrode deposited with catalysts, which provides a large triple-phase boundary area for nitrate removal reactions. The achieved nitrate removal rate is one order of magnitude higher than other literatures with high nitrate conversion and high selectivity of nitrogen. The carbon membrane itself had a limited catalytic property thus Cu-Pd bimetal catalysts were deposited inside the nano-pores to enhance the activity and selectivity. When Na2SO4 electrolyte was applied, the achieved single-pass removal of nitrate was increased from 55.15% (for blank membrane) to 97.12% by adding catalysts inside the membrane. In case of NaOH as the electrolyte, the single-pass nitrate removal efficiency, selectivity to nitrogen formation and nitrate removal rate was 90.66%, 96.40% and 1.47 × 10−3 mmol min−1 cm−2, respectively. Density functional theory studies demonstrate that the loading of bimetal catalysts compared with single metal catalysts enhances the adsorption of *NO3 on membrane surface favorable for N2 formation than NH3 on Cu-Pd surface. The application of catalytic carbon membrane nano-reactors can open new windows for nitrate removal due to the high reactor efficiency.