Ice-templating Method Research Articles

Effective solar-driven evaporators with urchin-like CuO particles and directional polyvinylidene fluoride scaffolds via directional dimethyl sulfoxide crystallization and non-solvent induced phase separation

Solar-driven evaporators with vertical channels usually exhibit excellent desalination due to the fast water transportation and excellent salt tolerance, which are often fabricated via a directional liquid nitrogen-assisted ice templating method and freeze-drying process. However, they are reliant on a very limited number of water-soluble polymers and hydrophilic inorganic materials, and the freeze-drying process costs a long time and much energy. A highly efficient and straightforward process for the fabrication of solar-driven evaporators with directional channels from water-insoluble materials is urgent. Here, water-insoluble polyvinylidene fluoride was dissolved in dimethyl sulfoxide (DMSO), and then the solution was engineered to PVDF scaffolds by the combination of directional DMSO crystallization with the commonly porous membrane formation method of non-solvent (water) induced phase separation. The result is the creation of oriented perpendicular pores to the surfaces and framberry-like microparticles on the pore walls. After the in situ deposition of urchin-like CuO particles with high solar adsorption on PVDF scaffolds, PVDF/CuO solar-driven evaporators have been successfully constructed. The evaporate rate depends on the PVDF content and CuO loading. Briefly, PVDF/CuO evaporators fabricated from high PVDF content of more than 3 wt% have low porosity, slow water supply, and poor hydrophilicity, resulting in a low evaporate rate and high evaporation enthalpy. The optimized 3D PVDF/CuO evaporator (V3-9 h) with a PVDF content of 3 wt% and CuO loading of 31.3 ± 1.6 wt% has a high pure water evaporation rate of 3.2 ± 0.2 and 3.5 ± 0.3 kg m-2h−1 under sun illumination at 1 and 2 kW m−2, respectively. And the evaporation enthalpy is as low as 1083.8 ± 25.5 J/g, 55 % lower than pure water. Moreover, the sample exhibits a similar evaporation rate in 3.5 wt% NaCl solution because the verticle channels endow the evaporator with excellent salt tolerance. The facile and scalable fabrication process of solar-driven evaporators with directional channels will greatly boost the development of cost-effective desalination.

Collaborative electrospinning and ice-templating for sea urchin-inspired aerogel microsphere: Unraveling functional mechanisms in thermally conductive phase change composites

With the increased integration of electronic devices, effective heat management becomes imperative. Thermally conductive phase change composites play a vital role by efficiently conducting heat and utilizing matrix phase change for heat storage. Conventional materials encounter difficulties such as low thermal conductivity, restricted heat storage density, and vulnerability to leakage. This study presents a novel method combining electrospinning and ice-templating method to produce aerogel microspheres with sea urchin-like structures, resolving mentioned issues. The microspheres exhibit a radial microstructure and controllable size, serving as efficient fillers for the easy production of high-performance phase change materials. The microspheres are able to create an efficient interlocking mechanism with surface spike structures, forming a continuous thermal conduction and spatially confined network in the composite material. At a filler content of 43.9 vol%, the thermal conductivity of the Al aerogel microsphere/paraffin composite reaches a peak value of 3.2 W/mK, accompanied by a contact thermal resistance of 1.2 × 10−6 Km2/W. Subjecting the composite to elevated temperatures well above the matrix's phase change temperature preserves its structural stability. This work reports a new structured filler moulding method that supports the development of high performance thermally conductive phase change composites.

Direct synthesis of porous aluminum nitride foams for enhancing heat transfer and anti-leakage performance of phase change materials

Organic phase change materials (PCMs) suffer from low thermal conductivity and easy leakage, which limit their application in heat storage and thermal management. In this work, porous AlN skeletons were synthesized to solve these problems of paraffin PCM. Using Al powders as raw material, porous AlN skeletons were prepared through the ice-templated method and the direct nitridation reaction. The skeletons were impregnated with paraffin to prepare phase change composites (PCCs). The thermal conductivity of the PCC with 55.6 wt% AlN reaches 9.1 W m−1 K−1 in the axial direction, which is 4550 % of paraffin. This PCC retains a high enthalpy of 105 J g−1 and has good thermal stability. Moreover, the porous AlN skeletons can effectively absorb paraffin so that all PCCs maintain a stable shape. This study provides a simple and efficient method to synthesize porous AlN and to solve the heat conduction and leakage issues of PCMs.

Bioinspired Zn-MOF doped radial porous chitosan-based sponge with antibacterial and antioxidant properties for rapid hemostasis and wound healing

Herein, a novel bioinspired radial porous zinc-based metal-organic framework (Zn-MOF) doped sodium alginate/chitosan derivatives/pullulan-based SA/PSCS/Pul/Zn-MOF (SPCP/Zn) composites sponge with excellent antioxidant and antibacterial properties was fabricated by the ice-templating method. Boric acid (BA) and Ca2+, which were respectively used as hydrogen- and ionic- bonding cross-linkers, provided strong mechanical properties for sponge matrix composed of SA, PSCS, and Pul. The obtained SPCP/Zn sponge exhibited uniform porous morphology, proper hydrophilicity, and admirable biocompatibility. In addition, the SPCP/Zn sponge achieved a sustained release of Zn2+ and gallic acid, which displayed powerful antibacterial and antioxidant activities. Importantly, the SPCP/Zn sponge exhibited shorter rapid hemostasis (20.4 ± 2.9 s) and lower blood loss (19.8 ± 4.3 mg). The SPCP/Zn sponge also showed faster wound closure ratio for the rat full-thickness skin defect model. It was revealed that SPCP/Zn sponge could significantly accelerate and enhance wound healing through downregulating inflammatory cytokines (TNF-α, IL-6) and increasing the expression of growth factors (VEGF). Due to its excellent properties, the SPCP/Zn sponge may have promising potential in wound healing applications.

A high thermal conductive BN-ZnO NWs/PVA composite based on the oriented structure construction using ice template method

The increasing demand for effective thermal management in electronic devices has highlighted the crucial importance of researching composite materials with exceptional thermal conductivity in the field of electronics. A novel hybrid filler consisting of hexagonal boron nitride (BN) and needle-like zinc oxide nanowires (ZnO NWs) was designed and synthesized in this work, then used to prepare thermally conductive composites by mixing it with polyvinyl alcohol (PVA) using the ice template method and hot-pressing process. The results demonstrated that a filler loading of 20 wt% yielded the highest thermal conductivity for the composite, reaching an impressive in-plane thermal conductivity of 1.77 Wm−1 k−1, which was 3.4 times higher than that of the conventional frozen pure PVA. This substantial improvement in thermal conductivity is mainly attributed to the synergistic effect achieved through the ice template method to construct a conventional orientation structure combined with the presence of BN-ZnO NWs hybrid filler. In addition, this composite also has good mechanical properties and thermal stability, etc. Our study shows that the BN-ZnO NWs/PVA thermally conductive composite demonstrates excellent potential as a thermal interface material for various applications in the field of thermal management of electronic devices.

The fabrication of a boron nitride/ammonium polyphosphate skeleton based on ice template method for thermal conductive and flame retardant epoxy

Epoxy (EP) is widely used in the field of high-speed communication and microelectronics. However, its poor thermal conductivity and high flammability bury the hidden danger of fire accident. In this work, the hexagonal born nitride (h-BN) combined with ammonium polyphosphate (APP) constructs a three-dimensional skeleton (3D-BN) via bidirectional freezing technology. The 3D-BN skeleton is immersed into the EP matrix to obtain the EP/3D-BN composite, which is endowed with high thermal conductivity and flame retardancy. When the loading of hexagonal born nitride (h-BN) is 9.1 vol%, the thermal conductivity of EP/3D-BN3 composite reaches 1.67 W m−1 K−1, which is increased by 944 % compared with that of the control EP. The peak heat release rate (PHRR) and total heat release (THR) of EP/3D-BN3 are significantly reduced by 54 % and 34 % respectively. This EP/3D-BN composite provides potential applications toward the industrial production for microelectronic devices.

Oriented Three-Dimensional Skeletons Assembled by Si3N4 Nanowires/AlN Particles as Fillers for Improving Thermal Conductivity of Epoxy Composites.

With the miniaturization of current electronic products, ceramic/polymer composites with excellent thermal conductivity have become of increasing interest. Traditionally, higher filler fractions are required to obtain a high thermal conductivity, but this leads to a decrease in the mechanical properties of the composites and increases the cost. In this study, silicon nitride nanowires (Si3N4NWs) with high aspect ratios were successfully prepared by a modified carbothermal reduction method, which was further combined with AlN particles to prepare the epoxy-based composites. The results showed that the Si3N4NWs were beneficial for constructing a continuous thermal conductive pathway as a connecting bridge. On this basis, an aligned three-dimensional skeleton was constructed by the ice template method, which further favored improving the thermal conductivity of the composites. When the mass fraction of Si3N4NWs added was 1.5 wt% and the mass fraction of AlN was 65 wt%, the composites prepared by ice templates reached a thermal conductivity of 1.64 W·m-1·K-1, which was ~ 720% of the thermal conductivity of the pure EP (0.2 W·m-1·K-1). The enhancement effect of Si3N4NWs and directional filler skeletons on the composite thermal conductivity were further demonstrated through the actual heat transfer process and finite element simulations. Furthermore, the thermal stability and mechanical properties of the composites were also improved by the introduction of Si3N4NWs, suggesting that prepared composites exhibit broad prospects in the field of thermal management.

Stable sodium-metal batteries with a hierarchical structured electrode toward reversible confinement of Na dendrites

Sodium metal is a promising candidate for the future of rechargeable batteries. However, a significant problem, that is, the growth of sodium dendrites, which are uncontrolled microscopic structures that reduce battery performance and stability, remains unaddressed. To resolve this issue, the development of three-dimensional (3D) nanostructured hosts to prevent dendrite growth and cease the buildup of inactive sodium has been proposed. However, research on developing an uncomplicated process to design these 3D hosts is currently lacking. In this study, we used the ice-templating method to form a self-supporting 3D hierarchical porous structure using a graphene oxide dispersion. This approach offers significant benefits in terms of scalability and cost-effectiveness. The resulting porous design offers numerous nucleation sites, which in turn reduce the intensity of local electric fields around dendrites and lower the current density. Consequently, sodium ions are deposited more evenly, which helps inhibit dendrite growth. Our test results indicated stable cycling performance, with 250, 200, and 150 cycles achieved for deposition volumes of 0.25, 0.5, and 1.0 mAh cm−2, respectively, at a constant current density of 0.25 mA cm−2. By utilizing in situ optical cell analysis, we observed the effective suppression of dendrite growth. Furthermore, ex situ examination confirmed the absence of dendrite formation, even at a high deposition capacity of 5.0 mAh cm−2. These results underline the potential of using a 3D hierarchical porous structure to effectively improve the performance and longevity of sodium-metal batteries.

Ice-templating co-assembly of dual-MOF superstructures derived 2D carbon nanobelts as efficient electrocatalysts

Here, we propose a novel synthetic strategy to fabricate a two-dimensional (2D) N-doped carbon nanobelt with high electrocatalytic activity using a dual-MOF superstructure precursor. The self-assembly mechanism induced by Van der Waals forces ensures the successful formation of a 2D ZIF-8/ZIF-67 dual-MOF superstructure through a straightforward ice-templating co-assembly method. Additionally, N-doped carbon derived from ZIF-8 can capture cobalt species from the adjacent ZIF-67 during the pyrolysis process, resulting in the coexistence of atomically dispersed Co single atoms and nanoparticles within the carbon nanobelt, effectively enhancing the intrinsic activity for the electrocatalytic oxygen reduction reaction (ORR). Furthermore, the interconnected hierarchically porous carbon nanocubes in the kinetic-favorable 2D carbon nanobelt superstructure can maximize the exposure of accessible active sites, overcome macroscopic mass transfer limitations, and accelerate the reaction kinetics. Hence, the as-prepared carbon nanobelt exhibits outstanding alkaline ORR catalytic activity with a half-wave potential of 0.888 V versus RHE, and the assembled Zn–air batteries display a prominent peak power density of 179 mW cm−1. The present work highlights the simplicity and versatility of the ice-templating assisted co-assembly strategy in preparing efficient 2D carbon-based superstructure electrocatalysts.

Linkage Effect Induced by Hierarchical Architecture in Magnetic MXene-based Microwave Absorber.

Hierarchical architecture engineering is desirable in integrating the physical-chemical behaviors and macroscopic properties of materials, which present great potential for developing multifunctional microwave absorption materials. However, the intrinsic mechanisms and correlation conditions among cellular units have not been revealed, which are insufficient to maximize the fusion of superior microwave absorption (MA) and derived multifunctionality. Herein, based on three models (disordered structure, porous structure, lamellar structure) of structural units, a range of MXene-aerogels with variable constructions are fabricated by a top-down ice template method. The aerogel with lamellar structure with a density of only 0.015g cm-3 exhibits the best MA performance (minimum reflection loss: -53.87dB, effective absorption bandwidth:6.84GHz) at a 6wt.% filling ratio, which is preferred over alternative aerogels with variable configurations. This work elucidates the relationship between the hierarchical architecture and the superior MA performance. Further, the MXene/CoNi Composite aerogel with lamellar structure exhibits >90% compression stretch after 1000 cycles, excellent compressive properties, and elasticity, as well as high hydrophobicity and thermal insulation properties, broadening the versatility of MXene-based aerogel applications. In short, through precise microstructure design, this work provides a conceptually novel strategy to realize the integration of electromagnetic stealth, thermal insulation, and load-bearing capability simultaneously.

An innovative graphene-based phase change composite constructed by syneresis with high thermal conductivity for efficient solar-thermal conversion and storage

Graphene-based phase change composites hold significant potential for solar energy utilization, but their poor thermal conductivity hinders their practical applications. In this work, an air-dried graphene skeleton (AGS) with excellent thermal conductivity enhancement efficiency was constructed by the ice templating method and syneresis, and the air-dried graphene phase change composite (AGP) was subsequently obtained through vacuum-impregnating n-Docosane (C22) into AGS. The syneresis effectively reduced the phonon scattering between graphene sheets within AGS and increased the density of AGS to 0.1701 g/cm³. Therefore, with a graphene skeleton loading of 23.82 wt.%, AGP exhibited excellent thermal conductivity of 9.867 W/(m K), outstanding electrical conductivity of 68.08 S/cm, and remarkable shape stability. Additionally, AGP demonstrated a melting enthalpy of 188.5 J/g and an outstanding solar-thermal conversion efficiency of 93.98%, showing enormous potential for the utilization of solar energy.

Preparation and characterization of bio-inspired full-biomass-derived aerogel with vertically aligned structure

Using renewable biomass resources to prepare porous materials can reduce the dependence on petroleum-based energy, promote green, low-carbon, and high-quality development, and achieve carbon neutrality. Here, we report a bio-inspired full-biomass-derived aerogel with an ultra-light (10.33–27.77 mg/cm3), highly porous (98.66–99.19 %), and vertically aligned structure. The fabrication involves an ultrasonic-assisted deep eutectic solvent (DES) extraction of cellulose nanofibrils (CNFs)-blending-directional freeze-drying-hydrophobic modification. Initially, CNFs were extracted from corncobs using DES pretreatment. Then, the aerogels were prepared by co-mixing CNFs with alkali lignin and freeze-drying the precursor suspension using the ice-templated method. Finally, the aerogels were modified using trimethoxymethylsilane chemical vapor deposition to render them hydrophobic. The silanization-modified aerogels exhibited superior static and dynamic hydrophobic properties, with a water contact angle of up to 153.4°, and demonstrated self-cleaning properties. These aerogels exhibited adsorption capabilities for various oils and organic solvents (9.6–29.8 g/g) and the ability to separate oil–water mixtures and adsorb methylene blue. Moreover, the aerogels with vertically aligned structures exhibited exceptional axial compression properties (up to 959 kPa), more than four times greater than the radial compression properties. Furthermore, the aerogels exhibited rapid liquid transport properties, with an axial transport rate of soybean oil that was more than 10 times higher than the radial transport rate. This study provides a green, eco-friendly, and sustainable strategy for preparing 3D porous aerogels, paving the way for developing full-biomass-derived aerogels as a promising alternative to petroleum-based adsorbent materials.

Preparation of porous GelMA microcarriers by microfluidic technology for Stem-Cell culture

Gelatin methacrylamide porous microcarriers (GelMA PMS), one of the most promising three-dimensional cell culture scaffolds, are limited in large-scale applications due to lack of ideal preparation method, unclear regulation of pore size on cell behavior and a lack of research on the entire cell culture process. Herein, combining microfluidic synchronous photo-crosslinking and ice-templating method, a low-cost, easy-assembly and suitable for scalability method is proposed to prepare GelMA PMS for bone marrow mesenchymal stem cells (BMSCs) expansion. The pore size of GelMA PMS can be controlled by adjusting the freezing temperature (-20 ℃, −60 ℃, −196℃). As a result, PMS 60 (frozen at −60 ℃) with the optimized pore size of 25.3 ± 3.2 μm exhibited the highest cell attachment ratio (90.2%) and the largest cell spreading area (0.516 mm2/MS). More importantly, PMS 60 displayed higher cell attachment efficiency, proliferation rate, adipogenic, osteogenic, and chondrogenic differentiation potential than commercial microcarriers Cytodex-1. Furthermore, BMSCs not only achieved bead-to-bead transfer on PMS 60 but also exhibited potent proliferation rate after transfer to new blank microcarriers. Cultured BMSCs were efficiently harvested from PMS 60 without damaging cell viability. In addition, the cryopreservation and thawing process did not affect the PMS 60 to support cell proliferation, while cells loaded on Cytodex-1 could not continue to proliferate. Therefore, GelMA PMS fabricated in this work shows great potential application and provides insights for MSCs culture.

Bio-derived 1T-MoS2/C-based aerogel by synergistic solar evaporation and tetracyclines removal for efficient freshwater generation

Tetracycline, a broad-spectrum antibiotic, has been widely used in disease treatment and other fields. However, due to the unreasonable use, tetracycline residue remains in water which eventually endangers human health. The green environmental protection, low-cost, and renewability biomass aerogel are highly attractive for the purification of tetracycline wastewater. Here, the flower-like 1T-MoS2 with S vacancies was uniformly grown on the supporting poplar catkin fibers-based biomass carbon matrix, which was constructed 3D porous aerogel by ice template method. The adsorption kinetics and adsorption isotherms model of MoS2/C-based aerogel for tetracycline in wastewater was investigated, revealing a maximum adsorption capacity of 124.4 mg g−1. More notably, the MoS2/C-based aerogel displayed excellent photothermal performance, which could synergistically raise the local temperature. The solar evaporation induced transpiration was able to accelerate the adsorption of tetracycline, owing to the endothermic behavior of tetracycline adsorption process. The MoS2/C-based aerogel attained an excellent water evaporation rate of 2.54 kg m−2 h−1 under one sun illumination, which is 11 times that of pure water. The solar purification prototype-based on MoS2/C-based aerogel could effectively remove tetracycline and generate freshwater. The freshwater production was about 33.6 kg m−2, and the tetracyclines were completed removed in the generation of condensed water on sunny days. The unique bifunctional capability of the MoS2/C-based aerogel paved a new strategy for tetracycline wastewater treatment and alleviated the dilemma of global water.

Design of carbonized unidirectional polyimide aerogel for CO2 capture: Effect of pore morphology/topology on CO2 capture

Design of efficient CO2 adsorbent is an effective way to capture CO2. Bamboo-derived activated carbon is a promising CO2 adsorbent. Inspired by this, carbonized unidirectional polyimide (CUPI) aerogels were newly designed by the ice templating method using directional freezing technology. The pore property of CUPI aerogel can be tuned by changing the solidification velocity, and a series of CUPI aerogels were designed to explore the CO2 capture performance in view of pore morphology/topology. As a result, the obtained CUPI-8 exhibits higher CO2 adsorption capacity compared to carbonized polyimide aerogels due to the synergistic effect of micropores and lamellar pores. Specially, the CO2 adsorption capacity over CUPI-8 can be up to 5.75 mmol/g at 20 bar and 298 K. Furthermore, the adsorption isotherm of CUPI-8 still shows an upward trend even nearly 20 bar. The isosteric adsorption heat (Qst) value of CUPI-8 is nearly in the ideal scope of 30–50 kJ mol−1. The efficient CO2 adsorption performance and good chemical stability of CUPI aerogel makes it a promising absorbent for practical application. This work provides a new opportunity for researching the effect of pore morphology/topology and the synergistic effect of hierarchical pores on CO2 capture.

Electrostatic-spinning construction of HCNTs@Ti3C2T x MXenes hybrid aerogel microspheres for tunable microwave absorption

Abstract Helical carbon nanotubes (HCNTs) are chiral materials that can form an induced magnetic field when current passes through them, making them a desirable material for absorbing microwaves. However, poor electrical properties and inert surfaces limit the application of HCNTs as sole materials. In this study, we develop HCNTs@Ti3C2T x MXenes hybrid aerogel microspheres synthesized using an electrospinning-assisted ice template method. The modified surfaces of the HCNTs form hydrogen bonds with Ti3C2T x MXenes to produce hybrid aerogel microspheres. Because of the different functionalized surfaces of HCNTs (F-HCNTs), F-HCNTs@Ti3C2T x MXenes could be adjusted to obtain effective reflection loss (RL) of microwaves ranging from 2 to 18 GHz. The observed advantageous RL is attributed to the modified surface of the HCNTs, their porous structure, and the optimized impedance matching derived from the synergistic effect between HCNTs and Ti3C2T x MXenes. Successful assembly method for the 3D architectures of HCNTs@Ti3C2T x MXenes hybrid aerogel microspheres significantly widens the practical applications of HCNTs in microwave absorption.

Electroactive HA/PDA/PPy stents applied for bone tissue engineering by layer-by-layer strategy

Bioelectric signals are an important factor that maintain cell functions and affect cell behavior. Conductive polymers (CPs) can facilitate cell activity and reinforce the signal transmission among cells, so CPs have triggered attention to the tissue regeneration. In this study, layer-by-layer strategy is employed and polyvinyl alcohol (PVA)/polylactic acid (PLA) braids are polymerized in polypyrrole (PPy) by ice template method. The stents that are deposited with PPy are then immersed in dopamine solution, which during polydopamine (PDA) is coated over the stents naturally. Finally, PDA is used as a template to form hydroxyapatite (HA) coating layer with the aim of electrochemical deposition. The test results indicate that PPy forms an even conductive network over the surface of braids while the electrochemically deposited HA made with PDA is adsorbed over the scaffolds in a needle pattern. According to the cyclic voltammetry measurement, the CV curves of HA/PDA/PPy scaffolds basically retain specified and thus the scaffolds possess stabilized electrochemical activity. At last, HA/PDA/PPy scaffolds are immersed in a simulated body fluid (SBF) for ten days and the surface is completely wrapped in HA, indicating an excellent biomineralization capability. MTT assay results suggest that the cell viability of composite scaffolds is improved by 188 %. This study provides a new perspective, a layer-by-layer structured bone scaffolds, broadening the application range of textile structure in the bone tissue engineering field.

Synergistic effects of oriented AlN skeletons and 1D SiC nanowires for enhancing the thermal conductivity of epoxy composites

As electronic devices are moving towards miniaturization and integration, the demand for ceramic/polymer composites with high thermal conductivity (TC) are increasing significantly. Herein, we reported a novel idea for rational design and delicate construction of anisotropic three-dimensional thermally conductive networks via the ice template method, using stearic acid-modified AlN particles (AlNm) as the primary filler and SiC nanowires (SiCNWs) as the secondary. As predicted, the as-prepared epoxy (EP)-based composites achieved a maximum TC of 2.56 W·m−1·K−1 in vertical direction at a filling fraction of 55 vol %, which was 12.8 times higher than that of pure EP. More importantly, the enhancement mechanism of composite TC was further demonstrated by realistic heat transfer process and finite element simulations. Furthermore, the prepared composites also displayed excellent thermal stability, high mechanical strength and good dielectric property, indicating that this strategy provides a promising insight for the design of high-performance thermal interface materials (TIMs).

Fabricating biomimetic materials with ice-templating for biomedical applications.

The proper organization of cells and tissues is essential for their functionalization in living organisms. To create materials that mimic natural structures, researchers have developed techniques such as patterning, templating, and printing. Although these techniques own several advantages, these processes still involve complexity, are time-consuming, and have high cost. To better simulate natural materials with micro/nanostructures that have evolved for millions of years, the use of ice templates has emerged as a promising method for producing biomimetic materials more efficiently. This article explores the historical approaches taken to produce traditional biomimetic structural biomaterials and delves into the principles underlying the ice-template method and their various applications in the creation of biomimetic materials. It also discusses the most recent biomedical uses of biomimetic materials created via ice templates, including porous microcarriers, tissue engineering scaffolds, and smart materials. Finally, the challenges and potential of current ice-template technology are analyzed.

Development and hydrogen permeation of freeze-cast ceramic membrane

BaCe0.65Zr0.20Y0.15O3-δ - Gd0.2Ce0.8O2-δ (BCZY-GDC) is currently one of the most investigated composites as ceramic membranes for H2 separation and membrane reactors. In this context, we will present for the first time the possibility to exploit the ice-templating method coupled with screen printing to obtain hierarchically-structured proton-conducting ceramic membranes. All the processing steps to obtain a defect free dense/porous structure were considered and analysed. In particular, the formulation of screen printing ink was optimized in terms of nature/amount of deflocculant and type of starting BCZY powder. An innovative membrane constituted by a 50 %-porous support with well-organized and aligned porosity and a 13 ± 3 μm thick dense layer on the top, was produced. The compressive strength (20.6 ± 5.6 MPa), were considered acceptable for practical applications. Promising H2 fluxes of 0.36 and 0.42 mL min-1 cm−2 at 750 °C, using a feed stream with 50 and 80% H2 in He (H2 %vol.) respectively, were obtained.