Tortuous Diffusion Research Articles

Designing tortuous gas diffusion path for hydrogen oxidation reaction and stability of solid oxide fuel cell: An engineered microstructural aspect in anode functional layer

Commercialization of solid oxide fuel cell (SOFC) is restricted due to long term performance degradation. SOFC is activated by diffusion of gasses through porous electrodes to the electrochemical active sites termed as triple phase boundary (TPB). Among all other parameters, tortuosity influences the functionality of TPB and is responsible for gas transport which relates its bulk diffusion and its migration through the porous electrode. The novelty of present research lies in designing of optimum tortuous gas diffusion path for effective hydrogen oxidation reaction through engineered morphology of anode functional layer. The study involves the fabrication of anode for planar SOFC using four configurations. Configuration A and B involves anode monolith synthesized through conventional route [(40 vol % Ni in dispersed-8 mol % Yttria stabilized zirconia (SZ)] and functional core-shell Ni@SZ. Configuration C (trilayer anode, TLA) is designed to have graded matrix with conventional Ni-SZ (fuel inlet side), 28 vol% Ni@SZ acting as active layer and 32 vol % Ni@SZ sandwiched in between. Configuration D consists of Ni@SZ as the active layer onto conventional Ni-SZ support. TLA is found to have minimum tortuosity (τ = 2) with maximum cell endurance for 2000 h (2.06–8.2 %/1000 h@800 °C under load). Ni@SZ with unimodal pore distribution is capable of reducing the activation barrier for charge migration (14 kJmol-1) compared to Ni-SZ (32 kJmol-1) with multimodal pores. This results in higher redox tolerance for Configuration B-D (4–7 % conductivity degradation/20 cycles) compared to Configuration A (27% conductivity degradation/20 cycles). Post mortem analyses of microstructure support the retention of core-shell morphology of Ni@SZ with lower deterioration.

A high-entropy cathode for sodium-ion batteries: Cu/Zn-doping O3-Type Ni/Fe/Mn layer oxides

The O3 layered oxides have been extensively investigated as cathode materials for sodium-ion batteries due to their remarkable theoretical capacity. However, the large radius of Na+ lead to complex phase transitions and tortuous diffusion channels during extraction/insertion, which ultimately restricts the Na+ diffusion kinetics and cyclic stability. In this study, we report a Zn and Cu co-doping strategy to the high entropy layer oxide Na [Ni0·2Fe0·2Mn0·4Cu0·15Zn0.05]O2 (HEO-CuZn) using the sol-gel method to prepare the oxides. Here, Zn is used to stabilize the structure of layer between the transition metal and O atoms, which slows down the adverse phase transition. In the fabricated sample, the element Cu provides additional capacity and inhibits excessive oxidation. The prepared HEO-CuZn used as cathode for Na+ ion battery exhibits better electrochemical performance, delivering a high specific capacity of 148 mA h g−1, and 84 % capacity retention after 100 cycles, which is attributed to the expanded Na+ transfer channels, reduced activation energy and interface side reactions, thus enhancing the Na+ diffusion kinetics. Meanwhile, the high entropy strategy stabilizes the overall structure by reducing the John-Teller distortion and suppressing the Na+/vacancy order, and effectively avoids adverse phase transitions such as O′3 and P′3. This study provides a new insight for the advance of the next generation high specific energy sodium-ion battery.

Harnessing Holey MXene/Graphene Oxide Heterostructure to Maximize Ion Channels in Lamellar Film for High-Performance Capacitive Deionization.

2D Ti3C2Tx MXene-based film electrodes with metallic conductivity and high pseudo-capacitance are of considerable interest in cutting-edge research of capacitive deionization (CDI). Further advancement in practical use is however impeded by their intrinsic limitations, e.g., tortuous ion diffusion pathway of layered stacking, vulnerable chemical stability, and swelling-prone nature of hydrophilic MXene nanosheet in aqueous environment. Herein, a nanoporous 2D/2D heterostructure strategy is established to leverage both merits of holey MXene (HMX) and holey graphene oxide (HGO) nanosheets, which optimize ion transport shortcuts, alleviate common restacking issues, and improve film's mechanical and chemical stability. In this design, the nanosized in-plane holes in both handpicked building blocks build up ion diffusion shortcuts in the composite laminates to accelerate the transport and storage of ions. As a direct outcome, the HMX/rHGO films exhibit remarkable desalination capacity of 57.91mg g-1 and long-term stability in 500mgL-1 NaCl solution at 1.2V. Moreover, molecular dynamics simulations and ex situ wide angle X-ray scattering jointly demonstrate that the conductive 2D/2D networks and ultra-short ion diffusion channels play critical roles in the ion intercalation/deintercalation process of HMX/rHGO films. The study paves an alternative design concept of freestanding CDI electrodes with superior ion transport efficiency.

Synergistic Enhancement of Electromagnetic Wave Absorption and Corrosion Resistance Properties of High Entropy Alloy Through Lattice Distortion Engineering

AbstractHigh entropy alloys (HEAs) are promising electromagnetic wave absorption (EMA) materials due to its designable crystal structure, variable electromagnetic properties, and excellent corrosion resistance. However, the impedance mismatch owing to the high electric and dielectric conductivity severely hinders the application of HEAs in the field of EMA. Herein, the lattice distortion of FeCoNiCu HEA is manipulated accurately by doping and annealing strategies to tailor the EMA properties. Significant lattice distortion is observed in the FeCoNiCuC0.37, which leads to a decrease in the electrical conductivity and the creation of abundant dipoles. Owing to the optimal impedance matching and boosted polarization loss, the FeCoNiCuC0.37 delivers a minimal reflection loss of −65.4 dB accompanied by an effective absorption bandwidth (EAB) of 6.81 GHz. After annealing at 200 °C, the EAB of the FeCoNiCuC0.37 is further increased to 7.99 GHz at 1.95 mm, which is better than that of most HEA‐based EMA absorbers reported so far. Moreover, it demonstrates excellent corrosion resistance owing to the more tortuous diffusion path of corrosive medium origin from lattice distortion. Thus, the study provides a new insight into designing high performance HEA‐based EMA materials with superior anti‐corrosion property by lattice distortion engineering.

Numerical Simulation of Mass Transfer in Hollow Fiber Membrane Module for Membrane-Based Artificial Organs.

The mass transfer behavior in a hollow fiber membrane module of membrane-based artificial organs (such as artificial liver or artificial kidney) were studied by numerical simulation. A new computational fluid dynamics (CFD) method coupled with K-K equation and the tortuous capillary pore diffusion model (TCPDM) was proposed for the simulations. The urea clearance rate predicted by the use of the numerical model agrees well with the experimental data, which verifies the validity of our numerical model. The distributions of concentration, pressure, and velocity in the hollow fiber membrane module were obtained to analyze the mass transfer behaviors of bilirubin and bovine serum albumin (BSA), and the effects of tube-side flow rate, shell-side flow rate, and fiber tube length on the bilirubin or BSA clearance rate were studied. The results show that the solute transport mainly occurred in the near inlet regions in the hollow fiber membrane module. Increasing the tube-side flow rate and the fiber tube length can effectively enhance the solute clearance rate, while the shell-side flow rate has less influence on the BSA clearance. The clearance of macromolecule BSA is dominated by convective solute transport, while the clearance of small molecule bilirubin is significantly affected by both convective and diffusive solute transport.

Vascular System Inspired 3D Electrolyte Network for High Rate and High Mass Loading Graphene Supercapacitor

AbstractHigh charge rate and high mass loading ability are of practical importance for high power and high volumetric performance supercapacitors but are always challenged by tortuous and sluggish ion diffusion in thick electrodes. Here, inspired by the hepatic vascular system, hierarchical 3D electrolyte networks are proposed to facilitate ion diffusion across laminar graphene films, resulting in a 14‐fold improved ion diffusion coefficient, better rate ability, and high mass loading ability for graphene supercapacitors. Such design enables graphene electrodes with high capacitance up to 236 F g−1, packing densities of 0.67–0.78 g cm−3 depending on structures; and core stack with 10 mg cm−2 mass loading exhibits a high energy density of 45.4 Wh L−1, which is among the state‐of‐the‐art graphene supercapacitors. This study provides a comprehensive investigation of structure‐related capacitive properties, guiding electrode design for high‐rate and high‐mass‐loading graphene supercapacitors. Moreover, such design also benefits solid‐state graphene supercapacitors by forming 3D gel electrolyte structures, which enable higher capacitance and better mechanical robustness, showing potential for flexible energy storage.

Heterostructure membranes of high permeability and stability assembled from MXene and modified layered double hydroxide nanosheets

Two-dimensional (2D) MXene-based lamellar membranes play transformative roles in membrane filtration technology. Their practical use in water treatment is however hindered by several hurdles, e.g., unfavorable swelling due to weak interactions between adjacent MXene nanosheets, tortuous diffusion pathways of layered stacking, and the intrinsic aquatic oxidation-prone nature of MXene. Herein, nanoporous 2D/2D heterostructure membranes are elaborately constructed via solution-phase assembly of oppositely charged MXene and modified layered double hydroxide (MLDH) nanosheets. As a multifunctional component, positively charged holey MLDH nanosheets were first tailor-made to serve simultaneously as a binder, spacer and surface-modifier; next they were intercalated into negatively charged MXene lamella to enhance structural stability and mass transfer of membranes. As a result, the as-prepared MLDH@MXene heterostructure membranes successfully break the persistent trade-off between high permeability and selectivity while mitigating the common drawbacks in 2D MXene-based lamellar membranes, e.g., swelling issues, restacking problems, and vulnerable chemical stability. Noticeably, at an operating pressure of 4 bar and a feed solution of 100 ppm of Congo red, the heterostructure membranes enable a threefold jump in permeability (332.7 ± 20 L m-2 h-1 bar-1) when compared to the pristine MXene membrane (119.3 ± 18 L m-2 h-1 bar-1), and better operational stability without compromising the rejection.

Nanocomposite proton conducting membranes based on sulfonated polystyrene/imidazole‐2‐acetic acid blend for direct methanol fuel cell application

AbstractNanocomposite polyelectrolyte membranes based on sulfonated polystyrene (SPS) /imidazole‐2‐acetic acid (Im) blend (SPSIm), incorporated with halloysite nanotubes (HNTs) were studied for direct methanol fuel cell (DMFC) applications. Firstly, PS was sulfonated at various degrees of sulfonation (DS), and the optimum DS was selected based on hydrolytic stability. Then, SPS was blended with Im as new proton conducting sites. In addition to increasing proton conductivity, methanol permeability decreased due to the attractive interaction between Im and SO3H groups in SPS. In the next step, to introduce tortuous diffusion pathways and hence decrease the methanol crossover, halloysite nanotubes were incorporated into the SPSIm matrix. The results show that the methanol permeability of the membrane incorporated with 1 wt% HNT (SPSIm/HNT) was around 0.527 × 10−7 cm2 s−1, which showed a significant decrease compared to SPS, causing an improvement in the membrane selectivity parameter in comparison to pristine SPS membrane. Furthermore, the thermal properties, ion exchange capacity (IEC), water uptake behavior, and performance of the membranes were evaluated. Based on the results, owing to the reduced methanol permeability, acceptable power density, ease of preparation, as well as low cost, SPSIm/HNT could be considered for DMFC applications.

Enhancement of barrier and corrosion protection performance of vinyl ester resin coating via incorporation of MXene nanosheets

Anti-corrosion performance of a vinyl ester resin coating was enhanced by intercalation of MXene nanosheets in the resin matrix through wet transfer method. Open circuit potential and electrochemical impedance spectroscopy tests was executed to evaluate the barrier and corrosion protection performance of the VER and MXene/VER composite coatings. The results revealed significant enhancement of the corrosion protection performance of the MXene/VER composite coating samples compared with that of the VER coating samples. The real impendence values of VER and MXene/VER composite coatings was 1.83 and 5.87 MΩ cm2, and the coating resistance was 1.72 and 5.74 MΩ cm2 after 40-days soaking in the 3.5 wt % of NaCl solution, respectively. The results indicate that the 0.1 wt % MXene/VER composite coating exhibited a significant improvement of coating resistance and real impendence by up to 320% and 330%, respectively. The impermeability makes the 2D MXene nanosheets acting as a good barrier to corrosive electrolyte, leading to a more tortuous diffusion pathway and enhanced corrosion protection performance.

Corrosion-Resisting Nanocarbon Nanocomposites for Aerospace Application: An Up-to-Date Account

The design and necessity of corrosion-resisting nanocarbon nanocomposites have been investigated for cutting-edge aerospace applications. In this regard, nanocarbon nanofillers, especially carbon nanotubes, graphene, nanodiamond, etc. have been used to fill in various polymeric matrices (thermosets, thermoplastics, and conducting polymers) to develop anti-rusting space-related nanocomposites. This review fundamentally emphases the design, anti-corrosion properties, and application of polymer/nanocarbon nanocomposites for the space sector. An electron-conducting network is created in the polymers with nanocarbon dispersion to assist in charge transportation, and thus in the polymers’ corrosion resistance features. The corrosion resistance mechanism depends upon the formation of tortuous diffusion pathways due to nanofiller arrangement in the matrices. Moreover, matrix–nanofiller interactions and interface formation play an important role in enhancing the corrosion protection properties. The anticorrosion nanocomposites were tested for their adhesion, contact angle, and impedance properties, and NaCl tests and scratch tests were carried out. Among the polymers, epoxy was found to be superior corrosion-resisting polymer, relative to the thermoplastic polymers in these nanocomposites. Among the carbon nanotubes, graphene, and nanodiamond, the carbon nanotube with a loading of up to 7 wt.% in the epoxy matrix was desirable for corrosion resistance. On the other hand, graphene contents of up to 1 wt.% and nanodiamond contents of 0.2–0.4 wt.% were desirable to enhance the corrosion resistance of the epoxy matrix. The impedance, anticorrosion, and adhesion properties of epoxy nanocomposites were found to be better than those of the thermoplastic materials. Despite the success of nanocarbon nanocomposites in aerospace applications, thorough research efforts are still needed to design high-performance anti-rusting materials to completely replace the use of metal components in the aerospace industry.

Microcrack Arrays in Dense Graphene Films for Fast-Ion-Diffusion Supercapacitors.

Laminated graphene film has great potential in compact high-power capacitive energy storage owing to the high bulk density and opened architecture. However, the high-power capability is usually limited by tortuous cross-layer ion diffusion. Herein, microcrack arrays are fabricated in graphene films as fast ion diffusion channels, converting tortuous diffusion into straightforward diffusion while maintaining a high bulk density of 0.92gcm-3 . Films with optimized microcrack arrays exhibit sixfold improved ion diffusion coefficient and high volumetric capacitance of 221Fcm-3 (240Fg-1 ), representing a critical breakthrough in optimizing ion diffusion toward compact energy storage. This microcrack design is also efficient for signal filtering. Microcracked graphene-based supercapacitor with 30µgcm-2 mass loading exhibits characteristic frequency up to 200Hz with voltage window up to 4V, showing high promise for compact, high-capacitance alternating current (AC) filtering. Moreover, a renewable energy system is conducted using microcrack-arrayed graphene supercapacitors as filter-capacitor and energy buffer, filtering and storing the 50Hz AC electricity from a wind generator into the constant direct current, stably powering 74LEDs, demonstrating enormous potential in practical applications. More importantly, this microcracking approach is roll-to-roll producible, which is cost-effective and highly promising for large-scale manufacture.

Application of ZIF nanosheets for construction of epoxy composite coatings with enhanced corrosion protection performance

Searching for nanofillers that have prominent barrier performance, good compatibility with polymer matrix and little chance of triggering galvanic corrosion remains a challenge in organic coating industries. In this study, ZIF nanosheets (ZIF-NS) were readily fabricated at room temperature and then used as additives in epoxy matrix for anticorrosion purpose. EIS demonstrated that epoxy doping with 0.5 wt% ZIF-NS possessed a resistance modulus at 0.01 Hz of 2.88 × 109 Ω·cm2 after immersion for 20 days, which was 2 orders of magnitude higher than that of neat epoxy. Owing to the restrained propagation of coating defects, as well as the tortuous diffusion channels for aggressive ions, ZIF nanosheets have showed great potential to form epoxy-based composite coatings on a large scale, and might pave the way for applications of other two-dimensional MOFs in industries.

Porous vermiculite membrane with high permeance for carbon capture

Two-dimensional (2D) membranes with interlayer nanochannels hold great promise for CO2 capture. However, the permeance is often limited by the high transmembrane resistance primarily caused by the tortuous interlayer diffusion pathway. Here, a facile method for preparing 2D porous vermiculite (PVMT) membranes is presented to boost CO2 transport by increasing the number of additional through-plane channels. The pristine vermiculite (VMT) nanosheets were treated with acid etching to generate nanopores by dissolving metal cations thereon. The resulting porous nanosheets were co-assembled with polyethyleneimine (PEI) molecules by vacuum-assisted self-assembly to fabricate PVMT-PEI membranes. The PEI molecules regulate the channel size to elevate the diffusion of CO2 and their amino groups afford affinity toward CO2 to increase its dissolution, thus intensifying the facilitated transport mechanism. The optimized PVMT-PEI membrane shows high performance with CO2 permeance of 568 GPU and CO2/CH4 selectivity of 27.6, which is 165% and 94% higher than pristine VMT membrane. In addition, the PVMT-PEI membranes exhibit good long-term operation stability.

Nacre-inspired biodegradable nanocellulose/MXene/AgNPs films with high strength and superior gas barrier properties

Super strength and high barrier properties are the bottleneck of the application of cellulose film materials. Herein, it is reported a flexible gas barrier film with nacre-like layered structure, in which 1D TEMPO-oxidized nanocellulose (TNF) and 2D MXene self-assembled to form an interwoven stack structure with 0D AgNPs filling the void space. The strong interaction and dense structure endowed TNF/MX/AgNPs film with mechanical properties far superior to PE films and acid-base stability. Importantly, the film presented ultra-low oxygen permeability confirmed by molecular dynamics simulations and better barrier properties to volatile organic gases than PE films. It is here considered the tortuous path diffusion mechanism of the composite film responsible for the enhanced gas barrier performance. The TNF/MX/AgNPs film also possessed antibacterial properties, biocompatibility and degradability (completely degraded after 150 days in soil). Collectively, the TNF/MX/AgNPs film brings innovative insights into the design and fabrication of high-performance materials.

Influence of hBN and MoS2 fillers on toughness and thermal stability of carbon fabric-epoxy composites

Hexagonal boron nitride (hBN) and molybdenum disulfide (MoS2) fillers of 2 to 8 wt.% influence on toughness, microhardness and thermal stability of carbon fabric-reinforced epoxy composite (CFREC) reported. Mode-I, mixed-mode I/II toughness and microhardness of CFREC improved due to the addition of hBN and MoS2 separately upto 6 wt.% filler loading. The epoxy matrix in CFREC modified by hBN and MoS2 strengthens the matrix, deflects the crack path and resists delamination. Toughness reduced beyond 6 wt.% filler addition due to agglomeration and poor fiber-filler-matrix bonding as revealed by the surface morphology of the fracture specimen. Thermal analysis reveals decomposition temperature at 25% weight loss increased from 395 to 430 °C and 395 to 411 °C due to 4 wt.% MoS2 and 4 wt.% hBN addition to CFREC respectively. Impermeable characteristics of MoS2 and hBN fillers caused tortuous diffusion path for gas molecules and delayed thermal decomposition.

3D hollow CoNi-LDH nanocages based MMMs with low resistance and CO2-philic transport channel to boost CO2 capture

Layered double hydroxide (LDH) bearing numerous hydroxyl groups shows high affinity with CO2 and is promising in mixed matrix membranes (MMMs) based CO2 capture. However, its non-porous structure limits the further improvement of CO2 permeability. In this work, 3D hollow CoNi-LDH nanocages were developed to construct low-resistance and CO2-philic transport channel in MMM by in-situ etching of ZIF-67 template. The resultant material exhibits hollow structure with cavity size of about 500 nm, mesopores and micropores from LDH stacking and ZIF-67 template. The outer layered CoNi-LDH nanosheets can attract more CO2 molecules by their abundant hydroxyl groups, resulting in an improvement in dissolution selectivity of CO2 over N2. Meanwhile, the tortuous gas diffusion paths originated from 2D nanosheet stacking can further enhance the CO2 selectivity over N2. Moreover, the hollow nanocages provide CO2 molecules with fast transport path, resulting in high CO2 permeability. As a result, compared with pure Pebax membrane and 2D LDH/Pebax MMM, all the 3D hollow CoNi-LDH/Pebax MMMs present enhanced CO2 permeability. The 3D hollow CoNi-LDH-2h/Pebax MMM performs the highest CO2 permeability of 135.49 Barrer, which are increased by 141.95% and 71.50% than those of the above two membranes, respectively. The selectivity of 3D hollow CoNi-LDH-2h/Pebax MMM is about 26.30% higher than that of the pure Pebax membrane. The present membrane presents comparable CO2 capture capacity in contrast with most reported Pebax based MMMs and surpasses the Robeson upper bond. Together with the good long-term stability, the 3D hollow CoNi-LDH nanocages are believed to be a promising candidate for MMMs to improve CO2 capture.

Non-layer-transformed Mn3O4 cathode unlocks optimal aqueous magnesium-ion storage via synergizing amorphous ion channels and grain refinement

Aqueous rechargeable magnesium ion batteries (ARMBs) have obtained more attention due to the two-electrons transfer nature, low cost and safety. However, the scarcity of cathode materials seriously hinders the development of ARMBs because of the unfavorable strong interaction between Mg2+ and cathode material. Herein, we choose a pre-treated spinel Mn3O4 cathode for aqueous Mg2+ storage. The pre-treatment in Na2SO4 solution induces the grain refinement decorated with tortuous amorphous ion diffusion channels, facilitating the production of electrochemical reaction active sites and the diffusion of Mg2+, respectively, which achieve a (sub-)surface pseudocapacitance reaction between Mn (II) and Mn (III). As a result, the pre-treated Mn3O4 cathode exhibits a package of optimal performances, i.e., a capacity of 98.9 mAh g−1 and a high capacity retention rate of 99.4% after 2000 cycles. To the best of our knowledge, our work not only provides a new reaction mechanism of spinel Mn3O4 in aqueous batteries system, but also affords a high cycle stability electrode material for rechargeable Mg2+ energy storage.

Fiber packing and morphology driven moisture diffusion mechanics in reinforced composites

Fiber reinforced polymer composite (FRPC) materials are extensively used in lightweight applications due to their high specific strength and other favorable properties including enhanced endurance and corrosion resistance. However, these materials are inevitably exposed to moisture, which is known to drastically reduce their mechanical properties caused by moisture absorption and often accompanied with plasticization, weight gain, hygrothermal swelling, and de-bonding between fiber and matrix. Hence, it is vital to understand moisture diffusion mechanics into FRPCs. The presence of fibers, especially impermeable like Carbon fibers, introduce tortuous moisture diffusion pathways through polymer matrix. In this paper, we elucidate the impact of fiber packing and morphology on moisture diffusion in FRPC materials. Computational models are developed within a finite element framework to evaluate moisture kinetics in impermeable FRPCs. We introduce a tortuosity factor for measuring the extent of deviation in moisture diffusion pathways due to impermeable fiber reinforcements. Two-dimensional micromechanical models are analyzed with varying fiber volume fractions, spatial distributions and morphology to elucidate the influence of internal micromechanical fiber architectures on tortuous diffusion pathways and corresponding diffusivities. Finally, a relationship between tortuosity and diffusivity is established such that diffusivity can be calculated using tortuosity for a given micro-architecture. Tortuosity can be easily calculated for a given architecture by solving steady state diffusion governing equations, whereas time-dependent transient diffusion equations need to be solved for calculating moisture diffusivity. Hence, tortuosity, instead of diffusivity, can be used in future composites designs, multi-scale analyses, and optimization for enabling robust structures in moisture environments.

Extended Barrier Lifetime of Partially Cracked Organic/Inorganic Multilayers for Compliant Implantable Electronics

Flexible and soft bioelectronics display conflicting demands on miniaturization, compliance, and reliability. Here, the authors investigate the design and performance of thin encapsulation multilayers against hermeticity and mechanical integrity. Partially cracked organic/inorganic multilayer coatings are demonstrated to display surprisingly year-long hermetic lifetime under demanding mechanical and environmental loading. The thin hermetic encapsulation is grown in a single process chamber as a continuous multilayer with dyads of atomic layer deposited (ALD) Al2 O3 -TiO2 and chemical vapor deposited Parylene C films with strong interlayer adhesion. Upon tensile loading, tortuous diffusion pathways defined along channel cracks in the ALD oxide films and through tough Parylene films efficiently postpone the hermeticity failure of the partially cracked coating. The authors assessed the coating performance against prolonged exposure to biomimetic physiological conditions using coated magnesium films, platinum interdigitated electrodes, and optoelectronic devices prepared on stretchable substrates. Designed extension of the lifetime preventing direct failures reduces from over 5 years yet tolerates the lifetime of 3 years even with the presence of critical damage, while others will directly fail less than two months at 37 °C. This strategy should accelerate progress on thin hermetic packaging for miniaturized and compliant implantable electronics.

Synergy of superhydrophobic layer and amino-functionalized graphene/epoxy coating towards corrosion/wear resistance on Al alloy

The poor dispersity of graphene in epoxy (EP) coating is harmful to exerting its barrier effect, and the protective efficiency of onefold coating has some difficulty to meet the ever-increasing demands of corrosion protection on Al alloy. Herein, a multilayer protection system (FG-SH-EP) coating was composed of a top superhydrophobic (SH) coating and a bottom amino-functionalized graphene/epoxy (FG-EP) coating. The as-designed multilayer protection system shows good water-repellent (the water contact angle is over 150°). The lowest-frequency impedance of FG-SH-EP is increased by an order of magnitude, because SH surface strengthens the water resistance for early safeguard and FG builds tortuous diffusion path for corrosion media towards physical barrier effect. Additionally, the anti-wear ability of FG-SH-EP is improved by about four times compared to single EP coating. The excellent anti-corrosion/wear behaviors of FG-SH-EP are attributed to the synergistic protection effect of SH-EP and FG-EP. This work is helpful to promote the application of multilayer strategy in alloy protection field.