Mass Transport Properties Research Articles

Continuous Graded Catalyst Layers for PEM Fuel Cells with Improved Humidity Range Tolerance

Abstract Grading electrodes is a promising approach to reduce ohmic and mass transport-related voltage losses in proton exchange membrane fuel cells. In graded electrodes, the ionomer and/or catalyst are spatially non-uniformly distributed to optimize performance over a wide operating range. In this study, through-plane ionomer gradients were fabricated with a simple wet-layer deposition technique that can readily be adapted in a roll-to-roll process. The presence of ionomer gradients was verified using scanning transmission electron microscopy and the profiles were found to be continuous despite using only two coating steps. Single cell tests revealed that the gradients outperform conventional electrodes and maintain the optimal performance for different relative humidities. These improvements were traced back to enhanced mass transport and protonic conduction properties identified by detailed electrochemical analysis. This manufacturing approach for electrodes offers an accessible toolbox to produce versatile and specialized multi-layered catalyst layers for different applications.

A multiphasic model for determination of mouse ascending thoracic aorta mass transport properties with and without aneurysm.

Thoracic aortic aneurysms (TAAs) are associated with aortic wall remodeling that affects transmural transport or the movement of fluid and solute across the wall. In previous work, we used a Fbln4E57K/E57K (MU) mouse model to investigate transmural transport changes as a function of aneurysm severity. We compared wild-type (WT), MU with no aneurysm (MU-NA), MU with aneurysm (MU-A), and MU with an additional genetic mutation that led to increased aneurysm penetrance (MU-XA). We found that all aneurysmal aortas (MU-A and MU-XA) had lower fluid flux compared to WT. Non-aneurysmal aortas (MU-NA) had higher 4kDa FITC-dextran solute flux than WT, but aneurysmal MU-A and MU-XA aortas had solute fluxes similar to WT. Our experimental results could not isolate competing factors, such as changes in aortic geometry and solid material properties among these mouse models, to determine how intrinsic transport properties change with aneurysm severity. The objective of this study is to use biphasic and multiphasic models to identify changes in transport material properties. Our biphasic model indicates that hydraulic permeability is significantly decreased in the severe aneurysm model (MU-XA) compared to non-aneurysmal aortas (MU-NA). Our multiphasic model shows that effective solute diffusivity is increased in MU-NA aortas compared to all others. Our findings reveal changes in intrinsic transport properties that depend on aneurysm severity and are important for understanding the movement of fluids and solutes that may play a role in the diagnosis, progression, or treatment of TAA.

Enhancing heat and mass transfer in MHD tetra hybrid nanofluid on solar collector plate through fractal operator analysis

Improved solar heat transfer methods are needed for the widespread use of solar energy. Due of their exceptional thermal characteristics, nanofluids have received a great deal of interest in this field. This research examines the use of tetra hybrid nanofluids in solar applications, with an emphasis on heat and mass transport properties. Due to their advantageous thermal characteristics, these nanofluids are well-suited for solar power production and other thermal applications. Accurate results for velocity, concentration, and temperature profiles are produced thanks to the model's use of fractal fractional derivatives and the Crank-Nicholson method for obtaining numerical solutions. In order to learn how different variables affect heat transport, parametric experiments are performed. The results show that tetra hybrid nanofluids greatly improve heat transfer performance over standard nanofluids. This improvement helps flat-plate solar collectors absorb more sunlight and increase their overall efficiency. The rate of mass transfer between phases may be quantified in the design and research of chemical reactors using the Sherwood number, an important quantity in chemical engineering. Its value is shown in a number of processes, including extraction, distillation, and catalytic reactions.

Nanoporous Cu-based amorphous alloys prepared by selective dissolution in acidic media

Abstract Functional nanoporous materials are considered a significant category of nanostructured materials that exhibit distinct characteristics like high surface area, porosity, and improved mass transport properties. These qualities render them suitable for a wide range of applications including catalysis, energy storage, biomedical fields, and electrochemical sensors. Dealloying or laser-induced technologies are the primary methods employed to fabricate such nanoporous materials. Dealloying is a dependable top-down approach used to produce hierarchical, disordered nanoporous materials with customizable pore sizes in the range of a few nanometers. The process of dealloying involves the selective elimination or dissolution of one or more elements from an alloy through a corrosion mechanism, using various dealloying techniques, such as chemical, electrochemical, liquid metal, or vapor phase dealloying. In the present study, copper-based amorphous metallic ribbons (Cu75Ni6Sn5P10Ga4) were initially manufactured using the melt-spinning method. The Cu-based amorphous ribbons were structurally investigated by X-ray diffraction and thermal analysis. Subsequently, the ribbons were subjected to a dealloying treatment, using an acidic solution to selectively dissolve the nickel from their composition and to obtain a nanoporous structure. The microstructure and chemical composition of the ribbons before and after the dealloying process were investigated using scanning electron microscopy (SEM), combined with energy-dispersive X-ray spectroscopy. The dealloying process performed in 1 M H2SO4 solution at 25 °C for 60 minutes leads to a large number of nanopores, uniformly distributed onto the surface of the Cu-based ribbons.

Numerical Analysis on Influence of Double-Sided 3D-Patterned Cathode Catalyst Layers on Polymer Electrolyte Fuel Cell Performance

Abstract An optimized cathode catalyst layer (CCL) design can improve fuel cell performance. In this study, we tried to optimize the structure by investigating the electrochemical properties of ion and mass transport through various CCL structures with ionomer layer (IL) added using simulation numerical analysis. In the simulation, an electrochemical calculation was performed on the structure with polymer electrolyte membrane (PEM) and IL of CCL using multi-block model. The simulation was conducted by changing the aspect ratio (AR) structure of width and height of IL to five conditions so that IL is evenly distributed in catalyst layer (CL). The result confirmed that CL 3D IL AR 4.9 structure with the highest aspect ratio showed good performance. In addition, cell performance improved as the uniform reaction area with protons conducting through IL increased and the resistance of protons decreased. Finally, cell performance was predicted based on changes in oxygen concentration (OC), relative humidity (RH), and ionomer/carbon (I/C) ratio. This numerical analysis can show the reaction according to environmental and structural changes and design an optimized structure to improve cell performance.

Porosity and permeability optimization of PEMFC cathode gas diffusion layer based on topology algorithm

The gas diffusion layer (GDL) is a crucial component in proton exchange membrane fuel cells (PEMFCs), significantly affecting mass transport and overall cell performance. Due to the pronounced pressure gradients and uneven mass transfer between the inlet and outlet of the serpentine flow field, this study proposes the design of a GDL with a concentration gradient to optimize performance. Leveraging topological optimization algorithms, the research focuses on enhancing the mass transport properties and improving cell efficiency. The optimization process considers the pressure distribution, oxygen concentration, and water content within the serpentine flow field as boundary conditions. By optimizing the porosity and permeability of the GDL in different regions, the study aims to enhance the GDL's mass transport capabilities. Simulation results demonstrate that initializing the porosity at 1 provides superior optimization, significantly enhancing mass transfer and overall cell performance. Although increased permeability contributes to improved mass transport, its impact is less significant compared to porosity optimization. Therefore, GDL porosity is identified as the dominant factor in enhancing cell performance, while permeability adjustments play a secondary role.

Evaluating diffusivity for efficient electrocatalytic conversion of carbon dioxide into multicarbon products using dealloyed hierarchically nanoporous copper

Hierarchical nanoporous copper (Hi-NPC) is a promising catalyst for carbon dioxide reduction reaction (CO2RR) due to its high surface area and excellent mass transport properties. To evaluate the effect of its architecture, eutectic-phased Cu18Al82 and single-phased Cu33Al67 were potentiostatically dealloyed to produce Hi-NPC and homogeneous nanoporous copper (Ho-NPC), respectively. At a comparable overpotential, the Hi-NPC electrocatalyst exhibited a significantly higher C2+ partial current density (jC2+) in CO2RR, reaching 510 mA/cm2, compared to both Ho-NPC (72 mA/cm2) and Cu electrodes (23 mA/cm2). When the current density was normalized by the electrochemically active surface area, the CO production among three electrodes demonstrated similar electrochemical behavior. However, notable differences were observed in the formation of C2H4 and C2H5OH, which can be attributed to the hierarchical structure of Hi-NPC facilitating C–C coupling to form C2 products. Although the Tafel plot indicated the CO2RR kinetics were identical for all three electrodes, linear sweep voltammetry experiments revealed that Hi-NPC exhibited the steepest current variation slope. Furthermore, the improved diffusivity was further confirmed by conducting oxygen reduction reactions with varying partial O2/N2 flow rates and electrochemical impedance spectroscopies. The hydrophobic properties of the electrode under various CO2RR current densities were also evaluated by water contact angle test.

Engineering the mass transport properties in potassium-ion intercalated pristine Prussian blue for sustainable potassium-ion batteries

Potassium-ion batteries (PIBs) could be a cheaper and more abundant alternative to lithium-ion batteries, offering faster charging and suitability for large-scale energy storage. Prussian blue (PB) is prepared through a simple wet chemical method, and its intercalation affinity for K+ ions is tested using linear sweep voltammetry (LSV). The diffusion resistance (Rw: ∼116 Ω Hz1/2) and low-frequency region slope (m: ∼0.63) are found high for the third LSV drive (Seg-3), indicating passivation of the PB surface which leads to a double-layer formation. Most of the K+ ions are intercalated into PB until three LSV segments. After that PB surface is passivated and prohibits further LSV-driven K+ ions intercalation. On average, the Seg-3 sample exhibits a 58 % higher lattice strain in comparison to the as-prepared PB. A capacity of 27 mAh g−1 @ 2 mA g−1 in aqueous media is recorded for the Seg-3 sample and a capacity drop of 4 mAh g−1 and Coulombic efficiency of 99.3 % is recorded under 100 cycles. These findings are further comprehensively validated through multi-technique approaches. The observed affinity and single-stage LSV-driven intercalation of K+ ions highlight the perspective of PB as an electrode material for aqueous potassium ion batteries (a-PIBs).

Faujasite/graphene nanoribbon hybrid adsorbent pellet for carbon dioxide capture

Pelletizing zeolite adsorbents is essential for practical applications, but conventional pelletization methods involve binders that can alter material properties. This study presents a one-pot approach to synthesizing FAU-type zeolite/graphene oxide nanoribbon (GONR) composite powders that can be pelletized by simple pressing without binders. This one-pot synthesis can be conducted without structure-directing agents, making the process simpler and more efficient. During zeolite crystallization, the particles decorate the strands of GONRs, effectively generating additional macropores and enhancing the pellets’ mechanical strength. Additionally, GONR suppresses water adsorption while maintaining good CO₂ adsorption, which improves the material’s performance under humid conditions. The FAU/GONR pellets exhibited enhanced mass transport properties compared to neat FAU pellets, as demonstrated by 10 times higher CO₂ permeability. The highest CO₂/N₂ selectivity of 76.5 was observed with 12 wt% GONR-containing pellet, and the performance was comparable to conventional pellets, while the fabrication procedure remained simple.

Constructing Hierarchical Zeolites with Highly Complete Framework via Controlled Desilication.

Desilication in alkaline medium has been widely used in construction of hierarchical zeolites for industrially relevant catalytic processes. The built of hierarchy in zeolites, especially with low aluminum stability or high Si/Al ratio, often suffers from uncontrolled destruction of zeolitic framework, accompanied by a significant loss of microporous domains and intrinsic acidity after desilication. Here, we report a novel and simple methodology for preparation of hierarchical zeolites with highly complete framework and minimum sacrifice of microporosity and acidity. The pre-impregnated amines in zeolite micropores act as inner pore-directing agents (iPDAs), largely protecting the zeolitic framework and moderating the silicon extraction during the alkaline treatment. The resulting hierarchical zeolites exhibit high crystallinity, tunable hierarchy, stable framework, and well-preserved acidity, endowing them with significantly improved mass transport properties and enhanced activities in catalytic conversion of methanol or furfural.

Development of Fe-Doped Ni2P-POx Electrocatalyst for Oxygen Evolution Reaction

Water electrolysis is extensively researched as a next-generation energy storage method to overcome the intermittency of renewable energy. Electricity generated from renewable sources such as solar and wind power can be converted into pure green hydrogen through water electrolysis. Despite the potential of green hydrogen as a renewable energy storage/carrier medium, the high overpotential resulting from the slow kinetics of oxygen evolution reaction (OER) and the use of expensive noble metals make cost-competitive hydrogen production a significant challenge. Anion exchange membrane water electrolysis (AEMWE) is one method for hydrogen production, offering economic advantages over proton exchange membrane systems as it allows for the use of relatively inexpensive transition metal catalysts like Ni, Fe, and Co due to its alkaline environment.Nickel phosphide (Ni2P)-based catalysts have emerged as highly promising candidates to accelerate the electrocatalytic OER. In particular, the introduction of Fe into Ni2P has been found to induce charge transfer, optimizing the electronic structure and accelerating the OER process. OER catalysts based on transition metal phosphides often exhibit a core-shell structure with phosphide at the core and oxide at the shell during OER measurements. This core-shell structure enhances OER performance through the oxide shell, complementing the deficient electrical conductivity of the phosphide core, resulting in superior catalytic activity and durability. From this perspective, transition metal phosphates are also being studied as electrocatalysts for OER. Phosphates, such as PO3 -, not only promote oxygen adsorbate adsorption but also induce a distorted local metal center geometry that favors OH- adsorption and further oxidation.To address these challenges, this study develops a facile and scalable synthesis of iron-doped nickel phosphide-phosphate (Fe-doped Ni2P-POx) nano-hybrid system as a superior noble-metal free OER powder-catalyst. The utilization of self-filling and pyrolysis approaches facilitates economically viable production of the highly porous phosphide catalyst with a high specific surface area and rough surfaces. X-ray diffractometer, X-ray photoelectron spectroscopy, and electron paramagnetic resonance elucidates the electronic structure modulation, resulting in phosphide-phosphate nano-hybrid structures. Consequently, the catalyst demonstrates excellent OER activity in 1 M KOH, with a significantly low overpotential of 283 mV at 20 mA cm-2, a small Tafel slope of 28.4 mV dec-1, and a superior exchange current density of 8.22 mA cm-2, surpassing state-of-the-art PGM catalysts. Furthermore, its durability over 20 hours indicates its excellent stability, mass transport properties, and mechanical robustness in alkaline media, underscoring its potential as an efficient OER catalyst to facilitate electrocatalytic hydrogen production. Figure 1

Design and Characterization of Porous Electrodes for Redox Flow Batteries

The commercialization of redox flow batteries as large-scale energy storage systems depends on lowering the capital and operating costs which depend on achieving maximum power density. Optimizing electrode design parameters and flow field-electrode combinations is critical to minimize losses and maximize active material utilization. Modeling the current drawn from an electrode offers a means to interpret electrode structure based on the electrolyte distribution driven by internal design. However, direct imaging methods (such as in-situ fluorescence microscopy and X-ray tomography) and numerical methods for current to potential prediction (3D Lattice Boltzmann modeling) are specific to individual electrode structures and possess limited predictable value to obtain an ideal electrode design. In this work, we present an electrode impedance spectroscopy (EIS)-based approach for determining electrode design parameters and devise a general method for determination of effective diffusion layer thickness. Using COMSOL modeling we verified the development of slug flow behavior in highly randomized porous electrode systems, indicating that the mass transport properties are dictated by inter-fiber distance. An analytical model to predict current as a function of applied overpotential is presented which allows us to vary structural parameters of the porous electrodes to study the influence of surface area, inter-fiber distances and diffusion layer thickness on the RFB performance. This model is a highly flexible tool applicable to any electrochemical system using a porous electrode and identifies critical variables affecting electrode design to characterize optimal electrode structure to minimize mass transport losses and optimize operational parameters.

High-Performance Optimised Porosity Iron Electrode for Hybrid Battery Electrolyzer

The growing demand for efficient, cost-effective and sustainable energy systems has prompted significant research into the development of advanced electrochemical devices. Hybrid battery electrolyzer, integrating the capabilities of both battery and electrolyzer, is a groundbreaking technology aiming to enhance both energy conversion efficiency and storage capacity. [1] Iron with large earth-abundance, low-cost, robustness, and high capacity is a promising electrode material for such hybrid energy systems. [2-4]This study focuses on the design, fabrication, and performance evaluation of a novel porous iron electrode tailored for use in a hybrid battery electrolyzer system. The proposed electrode exhibits superior electrocatalytic activity, enhanced mass transport properties, and increased surface area, contributing to improved overall performance. The electrode's porosity and pore structure are tuned to facilitate efficient mass transport and electrolyte penetration, addressing common challenges associated with conventional electrodes. The electrochemical performance of the optimised porosity iron electrode is investigated through comprehensive characterization techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and charge-discharge cycling tests. Results indicate superior electrochemical properties, showcasing enhanced specific capacity, faster charge/discharge kinetics, and prolonged cycle life compared to conventional electrodes. The incorporation of conducting nanocarbon and sintering at optimized temperature of 800 ℃ led to the achievement of a stable and elevated capacity exceeding 500 mAh/g for these advanced iron electrodes. The iron electrodes exhibit outstanding porosity (65 - 70%), along with a pore size of 5-10 µm. This configuration results in exceptional current rate performance, achieving a discharge capacity of 350 mAh/cm2 at a current density of 35 mA/cm2 and 245 mAh/cm2 at 50 mA/cm2. Furthermore, the iron electrodes exhibit superior performance in high-current electrolysis, showcasing an HER potential of -1.25, -1.34, and -1.50 V (vs Hg/HgO) at a current density of 200, 500 and 1000 mA/cm2 respectively.These findings highlight the potential of optimised porosity iron electrodes as a key component in the development of high-performance and cost-effective hybrid battery electrolyzer systems. The integration of such advanced materials holds promise for unlocking new frontiers in energy storage and green hydrogen technology, contributing to the realization of efficient and sustainable energy systems.

Which Insights Can Gas Diffusion Electrode Half-Cell Experiments Give into Activity Trends and Transport Phenomena of Membrane Electrode Assemblies?

In order to push the energy turnaround forward, research and development on technologies enabling storage and release of renewable energies, such as water electrolysis and fuel cells is vital in the current decade. For both processes it is essential to collect meaningful data for catalyst activity in terms of transferability to the industrial application already on the lab-scale and at an early stage of material development. Gas diffusion electrode (GDE) half-cell setups were recently presented as a fast and cost-effective tool to characterize oxygen reduction reaction (ORR) catalyst layers at fuel cell relevant potentials and current densities (3 A cm-2) [1]. An Inter-lab comparison demonstrated that GDE testing with various, slightly differing setups can deliver data that is both reliable and comparable if standardized measurement protocols are followed [2]. On the way to widespread application, it is essential to evaluate to which extend GDE half-cell measurements can provide reasonable trends of how catalyst layer properties influence ORR activity in membrane electrode assembly (MEA) applications, despite the major influence of the active metal itself. Elucidating possibilities and limitations of GDE half-cell measurements to study catalyst layer influences is scope of this study.The transferability of trends was studied for i) an ionic liquid modified and unmodified Pt/C catalyst (following our previous work [3]) and ii) employing nitrogen modified carbon support at different ionomer to carbon ratios (following the work of Ott et al. [4]). Regarding the activity increase due to IL modification we will show that rotating disk electrode (RDE) and GDE results at low current densities show the same trend. GDE testing also shows a maximum activity depending on the IL loading at slightly elevated current densities. In the high current density regime, however, MEA testing showed a negative effect of the IL modification, which was also obtained correctly within the GDE testing at the same current densities. For the N-doped Pt/C catalyst a positive effect was observed in MEA characterization with low ionomer content under dry conditions, where proton transport losses are dominant for the unmodified catalyst. However, at higher I/C ratio and under wet conditions, where proton transport is sufficient for both unmodified and N-doped catalyst, worse performance after N modification is observed in the high current density regime. During GDE evaluation only the latter phenomenon could be capture and the unmodified catalyst showed a superior performance over the N-doped material at any I/C ratio in the ohmic and in the mass transport limiting regime.In summary, we showed that GDE half-cell experiments, where the catalyst layer is in direct contact with the liquid electrolyte, can be used to reliably predict trends in catalytic activity for real MEAs at high current densities that are related to differences in oxygen mass transport [5]. However, differences in catalytic activity being related to proton accessibility especially at lower relative humidities cannot be captured completely, as the catalyst layer is always wetted fully. An introduction of an ionomer membrane between catalyst layer and liquid electrolyte might be necessary during GDE evaluation for a reliable description of all transport phenomena in real fuel cells. Nevertheless, our results indicate that GDE measurements without the utilization of an ionomer membrane allow for the study of oxygen mass transport properties independent of other transport phenomena at fuel cell relevant current densities.Literature:[1] Schmitt et al. Electrochemistry Communications 2022, 141, 107362 [2] Ehelebe et al. ACS Energy Lett. 2022, 7, 816-826. [3] Zhang et al. Advanced Functional Materials 31.28 (2021): 2010977 [4] Ott et al. Nature materials 19.1 (2020): 77-85. [5] Schmitt et al. Energy Adv. 2023, 2, 854.

Enhancement of Mass Transport in Catalyst Layers of HT-PEMFC with Tetrafluorophenyl Phosphonic Acid Binder.

The design and development of new and efficient catalyst binder materials are important for improving cell performance in high-temperature proton-exchange membrane fuel cells (HT-PEMFCs). In this study, a series of tetrafluorophenyl phosphonic acid-based binder materials (PF-y-P, y = 1, 0.83, and 0.67) with rigid structures and controllable degrees of phosphonation were prepared and used in HT-PEMFCs using the ultra-strong acid-catalyzed Friedel-Crafts reaction and the combined Michaelis-Arbuzov reaction. The samples exhibited high stability, low water uptake, superior proton conductivity, and cell performance. In addition, the oxygen mass transport properties of the PF-1-P binder were investigated using high-temperature microelectrode electrochemical testing techniques. Compared with the phosphoric acid-doped polybenzimidazole (PBI) binder, the O2 solubility of PF-1-P binder material increased by 30% (5.36 × 10-6 mol cm-3) and the PF-1-P binder material exhibited better cell stability in HT-PEMFCs. After 10.5 h of discharge at a constant current of 0.12 A cm-2, the MEA voltage decreased by 7.1% and 20.8% in case of the PF-1-P and PBI binders, respectively.

Extracting Thermodynamic, Kinetic, and Transport Properties from Batteries Using a Simple Analytical Pulsing Protocol

Gaining insights into the fundamental properties of lithium-ion batteries through scalable and non-destructive methods is challenging for commercial cell formats. In this work, a simple analytical pulsing protocol (APP) is performed on a commercial cell to understand its thermodynamic, kinetic, and mass transport properties. While testing procedures that rely on electrochemical pulses are well documented, the APP is novel in the level of fundamental insight that can be gained. For thermodynamics, a static-differential capacity analysis can be performed that removes the effects of kinetic and transport overpotentials and allows for the calculation of Gibbs free energy. For kinetics, the exchange current density of the cell can be calculated according to the Butler-Volmer model. For transport, a whole-cell lithium-ion diffusion coefficient can be calculated from a derivation of Fick’s second law and the generalized flux equation. Comparing the results from these properties gives an unparalleled level of mechanistic insight into battery performance from a single non-destructive technique. This APP requires no additional equipment and provides properties that can be easily correlated to materials or processing parameters. Therefore, the APP is valuable for research and development, manufacturing, quality assurance, and second-life applications, among others.

Advances in Light-Responsive Smart Multifunctional Nanofibers: Implications for Targeted Drug Delivery and Cancer Therapy.

Over the last decade, scientists have shifted their focus to the development of smart carriers for the delivery of chemotherapeutics in order to overcome the problems associated with traditional chemotherapy, such as poor aqueous solubility and bioavailability, low selectivity and targeting specificity, off-target drug side effects, and damage to surrounding healthy tissues. Nanofiber-based drug delivery systems have recently emerged as a promising drug delivery system in cancer therapy owing to their unique structural and functional properties, including tunable interconnected porosity, a high surface-to-volume ratio associated with high entrapment efficiency and drug loading capacity, and high mass transport properties, which allow for controlled and targeted drug delivery. In addition, they are biocompatible, biodegradable, and capable of surface functionalization, allowing for target-specific delivery and drug release. One of the most common fiber production methods is electrospinning, even though the relatively two-dimensional (2D) tightly packed fiber structures and low production rates have limited its performance. Forcespinning is an alternative spinning technology that generates high-throughput, continuous polymeric nanofibers with 3D structures. Unlike electrospinning, forcespinning generates fibers by centrifugal forces rather than electrostatic forces, resulting in significantly higher fiber production. The functionalization of nanocarriers on nanofibers can result in smart nanofibers with anticancer capabilities that can be activated by external stimuli, such as light. This review addresses current trends and potential applications of light-responsive and dual-stimuli-responsive electro- and forcespun smart nanofibers in cancer therapy, with a particular emphasis on functionalizing nanofiber surfaces and developing nano-in-nanofiber emerging delivery systems for dual-controlled drug release and high-precision tumor targeting. In addition, the progress and prospective diagnostic and therapeutic applications of light-responsive and dual-stimuli-responsive smart nanofibers are discussed in the context of combination cancer therapy.

Electroreduction of Captured CO2 on Silver Catalysts: Influence of the Capture Agent and Proton Source.

In the context of carbon reutilization, the direct electroreduction of captured CO2 (c-CO2RR) appears as an appealing approach since it avoids the energetically costly separation of CO2 from the capture agent. In this process, CO2 is directly reduced from its captured form. Here, we investigate the influence of the capture agent and proton source on that reaction from a combination of theory and experiment. Specifically, we consider methoxide-captured CO2, NH3-captured CO2, and bicarbonate on silver electrocatalysts. We show that the proton source plays a key role in the interplay of the chemistries for the electroreduction of protons, free CO2, and captured CO2. Our density functional theory calculations, including the influence of the potential, demonstrate that a proton source with smaller pKa improves the reactivity for c-CO2RR, but also increases the selectivity toward the hydrogen evolution reaction (HER) on silver surfaces. Since c-CO2RR requires an additional chemical protonation step, the influence of the proton source is stronger than that of the HER. However, c-CO2RR cannot compete with the HER on Ag, Experimentally, the dominant product observed is H2 with low amounts of CO being produced. Through a rotating cylinder electrode cell of well-defined mass-transport properties, we conclude that although methanol solvent exhibits a lower HER activity, HER remains dominant over c-CO2RR. Our work suggests that methoxide is a potential alternative capture agent to NH3 for direct reduction of captured CO2, though challenges in catalyst design, particularly in reducing the onset potential of c-CO2RR to surpass the HER, remain to be addressed.

A Review: Surface Engineering of Lipid-Based Drug Delivery Systems.

This review explores the evolution of lipid-based nanoparticles (LBNPs) for drug delivery (DD). Herein, LBNPs are classified into liposomes and cell membrane-based nanoparticles (CMNPs), each with unique advantages and challenges. Conventional LBNPs possess drawbacks such as poor targeting, quick clearance, and limited biocompatibility. One of the possible alternatives to overcome these challenges is surface modification of nanoparticles (NPs) with materials such as polyethylene glycol (PEG), aptamers, antibody fragments, peptides, CD44, hyaluronic acid, folic acid, palmitic acid, and lactoferrin. Thus, the main focus of this review will be on the different surface modifications that enable LBNPs to have beneficial properties for DD, such as enhancing mass transport properties, immune evasion, improved stability, and targeting. Moreover, various CMNPs are explored used for DD derived from cells such as red blood cells (RBCs), platelets, leukocytes, cancer cells, and stem cells, highlighting their unique natural properties (e.g., biocompatibility and ability to evade the immune system). This discussion extends to the biomimicking of hybrid NPs accomplished through the surface coating of synthetic (mainly polymeric) NPs with different cell membranes. This review aims to provide a comprehensive resource for researchers on recent advances in the field of surface modification of LBNPs and CMNPs. Overall, this review provides valuable insights into the dynamic field of lipid-based DD systems.

Measuring Mass Transfer of n-Hexane and 2-Chloroethyl Ethyl Sulfide in Sorbent/Polymer Fiber Composites Using a Volumetric Adsorption Apparatus.

The integration of metal-organic frameworks (MOFs) into composite systems serves as an effective strategy to increase the processability of these materials. Notably, MOF/fiber composites have shown much promise as protective equipment for the capture and remediation of chemical warfare agents. However, the practical application of these composites requires an understanding of their mass transport properties, as both mass transfer resistance at the surface and diffusion within the materials can impact the efficacy of these materials. In this work, we synthesized composite fibers of MOF-808 and amidoxime-functionalized polymers of intrinsic microporosity (PIM-1-AX) and measured the adsorption and mass transport behavior of n-hexane and 2-chloroethyl ethyl sulfide (CEES), a sulfur mustard simulant. We developed a new Fickian diffusion model for cylindrical shapes to fit the dynamic adsorption data obtained from a commercial volumetric adsorption apparatus and found that mass transport behavior in composite fibers closely resembled that in the pure PIM fibers, regardless of MOF loading. Moreover, we found that n-hexane adsorption mirrors that of CEES, indicating that it could be used as a structural mimic for future adsorption studies of the sulfur mustard simulant. These preliminary insights and the new model introduced in this work lay the groundwork for the design of next-generation composite materials for practical applications.