Porous Structure Research Articles

Research on freeze resistance and life prediction of Desert sand–Crushed stone fine aggregate concrete

Despite the global abundance of Desert sand (DS), its application in engineering remains limited. This application can help alleviate challenges related to high unit costs and the scarcity of natural fine aggregate supplies. Freeze resistance experiments were conducted on C30 concrete incorporating varying proportions of DS, including 0 %, 25 %, 50 %, 75 %, and 100 %. DS was mixed with Tuff crushed stone fine aggregate (Manufactured sand, referred to as MS). The freeze durability of the composite fine aggregate concrete was comprehensively evaluated from three perspectives: surface morphology, a macroscopic analysis including mass loss and relative dynamic elastic modulus (RDEM), and microscopic examinations encompassing pore structure observation and scanning electron microscope (SEM) imaging. Utilizing the damage degree index of the dynamic elastic modulus and the Weibull distribution model, the life prediction process was conducted to elucidate the time-varying behavior of DS-MS concrete. According to the test findings, the concrete specimen DS25-MS75 demonstrates the highest freeze resistance. The mass loss rate shows a pattern of initial decrease followed by an increase with higher desert sand admixture, whereas the RDEM initially increases and then decreases. Optimal desert sand admixture levels can prevent and delay concrete degradation, thereby enhancing its freeze resistance. Excessive desert sand content leads to increased water demand during the curing process, resulting in elevated porosity and facilitating the formation of voids. Under the action of freezing and thawing cycles in water, DS25 %-MS75 % concrete has the longest expected service life with an actual life of 101 years, while DS100 %-MS0 % concrete has the shortest service life with an actual life of only 54.5 years.

A Facile Strategy for Preparing Flexible and Porous Hydrogel-Based Scaffolds from Silk Sericin/Wool Keratin by In Situ Bubble-Forming for Muscle Tissue Engineering Applications.

In the present study, it is aimed to fabricate a novel silk sericin (SS)/wool keratin (WK) hydrogel-based scaffolds using an in situ bubble-forming strategy containing an N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) coupling reaction. During the rapid gelation process, CO2 bubbles are released by activating the carboxyl groups in sericin with EDC and NHS, entrapped within the gel, creating a porous cross-linked structure. With this approach, five different hydrogels (S2K1, S4K2, S2K4, S6K3, and S3K6) are constructed to investigate the impact of varying sericin and keratin ratios. Analyses reveal that more sericin in the proteinaceous mixture reinforced the hydrogel network. Additionally, the hydrogels' pore size distribution, swelling ratio, wettability, and in vitro biodegradation rate, which are crucial for the applications of biomaterials, are evaluated. Moreover, biocompatibility and proangiogenic properties are analyzed using an in-ovo chorioallantoic membrane assay. The findings suggest that the S4K2 hydrogel exhibited the most promising characteristics, featuring an adequately flexible and highly porous structure. The results obtained by in vitro assessments demonstrate the potential of S4K2 hydrogel in muscle tissue engineering. However, further work is necessary to improve hydrogels with an aligned structure to meet the features that can fully replace muscle tissue for volumetric muscle loss regeneration.

Experimental Investigation of the Influence of Composition Changes in Shale on Pore Structure and Fractal Characteristics under Different HCl Concentrations

Experimental Investigation of the Influence of Composition Changes in Shale on Pore Structure and Fractal Characteristics under Different HCl Concentrations

Study on properties and CO2 emission of self-pulverizing calcium sulfoaluminate (SPCSA) after carbonization curing

The extensive use of Portland cement (OPC) has resulted in a steady rise in CO2 emissions from the construction industry, posing a significant climate threat. While adopting low-carbon cement enriched with belite minerals holds promise for substantial CO2 emission reduction in the cement industry, the limited early hydration activity of C2S constrains its engineering applications. Carbon capture, storage, and utilization (CCUS) technology, capable of rapidly developing the strength of C2S, opens up a new avenue for utilizing low-carbon cement. This study evaluated the properties of self-powdering calcium sulfoaluminate (SPCSA) cements with different C2S contents, and the carbon emissions during production and application were analyzed. The samples' carbonation area, compressive strength, and capillary water absorption properties were tested. The carbonation products and pore structures were also characterized using XRD, TGA, SEM, and Low-NMR. The results show that when the molar ratio of C4A3S̅ to C2S is 1:12 (S̅12), the compressive strength and CO2 sequestration of SPCSA are 69.78 MPa and 0.15 g/g, respectively. When CCUS technology is adopted, the CO2 emission during the production and application of SPCSA is 585.78 kg/t, much lower than that of OPC of 878.28 kg/t. This is significant as a reference for realizing carbon neutrality in the cement industry.

Direct Conversion of Metal Organic Frameworks into Porous Rugby Phosphides by Plasma for Oxygen Evolution.

Electrolytic seawater is a green, sustainable, and promising approach for hydrogen production. Benefiting from the cost-effectiveness, crystal structures, and tailorable modification, transition metal phosphides become a highly attractive catalyst for the electrolysis of water. Considering the sufficient exposure and intrinsic catalytic activity of metal sites, here, carbon layer-coated NiFeP nanocrystals with a porous rugby structure are synthesized by Ar-H2 plasma. Activated PH radical in plasma is the key point to achieve phosphatization at a low temperature. The obtained porous rugby NiFeP catalyst exhibits excellent catalytic activity under alkaline conditions (300 mV in freshwater and 370 mV in seawater, 1000 mA cm-2), good corrosion resistance, and superior operational stability (>100 h). Theoretical calculations prove that Fe introduction and subsequent phosphorization weaken the adsorption of *O and *OH, thus improving the oxygen evolution reaction performance. Plasma phosphorization offers exciting opportunities for the in situ modification of other types of framework materials.

Production and optimization of activated carbon from plant waste with high specific surface area for moisture-saving applications in agriculture

In conditions of water shortage, sustainable agricultural development requires the use of water-saving technologies, including the use of water-retaining substrates based on activated carbon. In this work, the textural and adsorption characteristics of activated carbon obtained from plant waste were studied at different mass ratios of the sorbent and KOH (1:1, 1:2, 1:3 and 1:4). The aim of the study was to determine the optimal activation conditions for creating a material with a high specific surface area and a developed porous structure. The results showed that the largest pore volume (1.6 cm3/g) and a high degree of microporosity are achieved at a ratio of 1:3, which is confirmed by the analysis of pore distribution using the DFT and BJH methods. FTIR spectroscopy revealed the presence of functional groups (O–H, C=O and C–O) that contribute to water conservation. The differential pore volume distribution (dv(r), cm3/Å/g) also demonstrated that at a ratio of sorbent and KOH (1:3), the sample structure optimally combines micropores and mesopores, which increases the adsorption capacity of carbon.

Pore-Scale multi-objective shape optimization of triply periodic minimal surface cellular architectures: Volumetric Nusselt number versus friction factor

Triply Periodic Minimal Surface (TPMS) cellular architectures, i.e., minimal surfaces that are periodic in three independent directions, have attracted interest in the engineering community for their potential in heat transfer applications with severe volume constraints due to their high surface-to-volume ratio, unique geometrical properties and smooth porous structure. Such performance can be conveniently controlled by tuning the TPMS unit type, relative density, and structural parameters. In this study, a multi-objective optimization process is carried out to investigate how pore-scale geometric characteristics affect the heat transfer performance of TPMS, and which combinations result in an optimal trade-off between heat dissipation capability and associated pressure drop in terms of the Nusselt number and friction factor. The analysis is performed using an in-house Genetic Algorithm routine that generates the structure, allowing for a wider and denser range of investigation, and incorporates a commercial finite element CFD software as a black box fitness function. Over 14,000 unique combinations between two heat transfer boundary conditions (constant wall heat flux, fixed wall temperature) and several flow inlet conditions are investigated. The optimization achieved an increase in performance of up to 245 % in terms of volumetric Nusselt number, which was accompanied, however, by a significant, although reasonable, increase in friction factor values. The results also show specific trends among the geometric characteristics studied, which are then contextualized through the use of CFD analysis. Finally, empirical correlations are derived to cluster the non-dominated solutions obtained, enabling the reader to choose the best cellular TPMS structure by selecting the desired level of trade-off between convection heat transfer and flow resistance.

Engineering heterojunction noble metal (NM)@ZnO catalyst for improved CH4 photocatalytic oxidation

The photo-oxidation of methane into value-oxygenated products using H2O2 and H2O as an oxidant under atmospheric pressure represents a desired sustainable strategy for the production of commodity chemicals. However, controlling the products and maintaining high yields poses significant challenges. In this study, we propose an efficient strategy involving the design of noble metal (Au, Pd)/ZnO photocatalysts to enhance the productivity of oxygenates through CH4 photocatalytic oxidation. The prominent product, CH3OH, is achieved with a high yield of 1900 μmol/g. The unique combination and porous structures of Au/ZnO synergistically promote its conversion performance. Additionally, photoluminescence results provide direct evidence of the main intermediates involved in producing CH3OH and multi-carbon oxygenates. The findings of this research offer valuable insights into the fundamental oxidation mechanisms underlying photocatalytic CH4 conversion.

Fabrication and development of mechanical metamaterials via additive manufacturing for biomedical applications: A review

Abstract In this review, we provide a comprehensive overview of additive manufacturing (AM) technologies and materials as well as design possibilities to manufacture metamaterials for a variety of biomedical applications, of which many are inspired by nature itself. It is described that how new AM technologies (such as continuous liquid interface production and multiphoton polymerization) and new developments in more mature AM technologies (such as powder bed fusion, stereolithography and extrusion-based bioprinting) have led to more precise, efficient, and personalized biomedical components. Extrusion-based bioprinting, specifically, is a revolutionary topic creating intricate models with remarkable mechanical compatibility of metamaterials, such as negative/zero Poisson's ratio and stress elimination for tissue engineering and regenerative medicine. By exploiting a variety of designs for porous structures (such as truss, triply periodic minimal surface, and plant/animal-inspired and functionally graded lattices), AM made bioactive bone implants, artificial tissues and organs are made for tissue replacement purposes. The material palette of the AM metamaterials has also become very diverse nowadays ranging from metals and alloys (such as titanium and cobalt-chromium alloys) to polymers (like biodegradable polycaprolactone (PCL) and polymethyl methacrylate (PMMA)) which could be even integrated within bioactive bioceramics. These advancements are driving the progress of biomedical technology, improving human health and quality of life for future generations.

Synergistic pH-responsive MUC-1 aptamer-conjugated Ag/MSN Janus nanoparticles for targeted chemotherapy, photothermal therapy, and gene therapy in breast cancer

Drug resistance in cancer treatment, primarily attributed to the overexpression of the multidrug resistance (MDR) gene, significantly hampers the effectiveness of chemotherapy. This mechanism, driven by the increased production of P-glycoprotein (P-gp) efflux pumps, highlights the urgent need for innovative strategies to combat drug resistance in cancer patients. This study explores the application of antisense technology to suppress MDR gene expression, while addressing the challenges of instability and limited cellular uptake associated with antisense oligonucleotides. We synthesized Janus silver-mesoporous silica nanoparticles (Ag/MSN JNPs) using a sol-gel method, characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS), revealing uniformly sized, dumbbell-shaped nanoparticles with an average size of 285 ± 5.12 nm. Doxorubicin (DOX) was loaded into the porous structure of the mesoporous silica, and JNPs were functionalized with chitosan (CS) to incorporate P-gp antisense and a MUC-1 aptamer, serving as a pH-responsive gatekeeper. Our findings indicate that the Ap-As-DOX-JNPs achieved a remarkable 89 ± 0.59 % cell death in drug-resistant MCF-7/ADR cells after 48 h, alongside an 80 % reduction in P-gp expression. The combination of DOX, antisense technology, and photothermal therapy utilizing these JNPs demonstrates a promising strategy to effectively overcome drug resistance. Notably, normal MCF-7 cells exhibited reduced viability from 39.11 ± 1.12 % to 30.05 ± 1.07 % when treated with DOX-JNPs under near-infrared (NIR) irradiation. These results underscore the potential of utilizing MUC-1 aptamer-conjugated Janus nanoparticles in conjunction with chitosan as a gatekeeper to enhance the efficacy of chemotherapy, photothermal therapy, and gene therapy in overcoming multidrug resistance in cancer treatment.

Spatially Immobilized PtPdFeCoNi as an Excellent Bifunctional Oxygen Electrocatalyst for Zinc–Air Battery

AbstractDeveloping efficient oxygen electrocatalysts with low cost, high catalytic activity, and robust stability remains a formidable challenge for rechargeable zinc–air batteries (ZABs). Herein, highly dispersed ultrasmall PtPdFeCoNi high‐entropy alloy nanoparticles with a size of ≈ 2 nm and randomly distributed multimetallic single atoms spatially immobilized on the 3D hierarchically ordered porous nitrogen‐doped carbon skeleton (denoted as PtPdFeCoNi/HOPNC) are successfully synthesized via ultra‐rapid Joule heating process. The spatial immobilization on 3D HOPNC skeleton is the key to the high dispersion of multi‐active sites of oxygen electrocatalysts, and the formed hierarchical pore structure is conducive to the successful construction of the rapid mass transfer channel. As a result, the as‐prepared PtPdFeCoNi/HOPNC exhibits a positive half‐wave potential of 0.866 V versus RHE for oxygen reduction reaction (ORR), a low overpotential of 310 mV at 10 mA cm−2 for oxygen evolution reaction (OER), and low Tafel slopes for both ORR and OER. Furthermore, ZAB using PtPdFeCoNi/HOPNC as bifunctional oxygen catalysts exhibits excellent rate performances and superior cycling stability, surpassing that of a commercial Pt/C‐RuO2 mixture. The spatial immobilization strategy of HOPNC provides a new idea for the design and synthesis of efficient catalysts for various applications.

Understanding the Relationship of Closed Pore Structure in Biomass- derived Hard Carbon with Cellulose Regulating Strategy.

Recycling waste biomass to pyrolytic carbon has become a development direction of sodium-ion batteries (SIBs)anodes. However, it remains a challenge to precisely control the composition and structure of biomass to modify the properties of derived carbon. Herein, a strategy of hydrolyzing cellulose in phellem with sulfuric acid is proposed, which can promote cellulose fracture, reduce the graphitization and increase the content of closed pores in hard carbon. Accordingly, after the regulation of closed pore structure, the reversible capacity increased from 207 to 330 mAh g-1 at 20mA g-1, realizing an increase of ≈130 mAh g-1 in the plateau region and the initial Coulombic efficiency (ICE) is enhanced from 78% to 90%. When applied in full cell with O3-Na[Ni1/3Fe1/3Mn1/3]O2, it showed an energy density of 247Wh kg-1. This strategy has certain universality, and it provides the feasibility to use low-value cellulose-containing biomass to fabricate high-performance hard carbon materials.

Efficient Adsorption and Degradation of Tetracycline Hydrochloride Using Metal-Organic Framework-Derived Cobalt-Based Catalysts and Mechanism Insight.

High-performance Co-based catalysts were derived by pyrolysis using synthesized MOFs as self-sacrificial templates. Various catalytic systems were constructed by peroxymonosulfate (PMS) to degrade tetracycline hydrochloride (TC). Adsorption-degradation efficiencies, cycle performance, dynamics, and the adsorption catalytic mechanism of various catalytic systems for TC were studied. The effects of different synthetic solvents, pyrolysis temperatures, and single/bimetallic element compositions on degradation efficiency were innovatively compared. The optimal catalyst and PMS dosage for the experiment were determined to be 10 mg and 0.1 mL, respectively. The results indicated that all catalytic systems could efficiently degrade TC and have a high acid-base resistance. The catalyst activity was significantly influenced by the pyrolysis temperature. The optimum pyrolysis temperatures for Zn@Co-N-C-T, CH3OH@Co-N-C-T, and H2O@Co-N-C-T were 1000, 900 and 900 °C, respectively. More abundant pore structures and active sites were generated in Zn@Co-N-C-1000, exhibiting an excellent TC degradation efficiency and adsorption capacity, achieving 94.73% and 167.564 mg/g, respectively. Meanwhile, the total organic carbon (TOC) of TC (50 mL, 50 mg/L) achieved a removal rate (TOC/TOC0) of 50.28%. Zn@Co-N-C-1000/PMS maintained over 83.27% TC degradation after five cycles. The adsorption mechanism of the catalyst for TC was investigated through the analysis of adsorption kinetics and isotherm models. The quenching test and EPR results indicated that TC was primarily degraded through the nonradical pathway. The efficient degradation of TC is attributed to the rapid electron transfer processes occurring at the two-phase interface and the redox cycling of Co0/Co2+/Co3+. Finally, LC-MS was used to analyze the intermediate products of TC degradation in the Zn@Co-N-C-1000/PMS system, and two degradation pathways were proposed.

Research on improving permeability of granite reservoir: Polyhydrogen chelating acid acidizing

ABSTRACT Acidization is a highly effective technique for increasing oil well productivity. Therefore, it is critical to study effective stimulation of low-permeability granite reservoirs using acidification. Using the granite reservoir of Baobab oilfield in Chad as the research object, the properties of reservoir rocks were tested using XRD and rock thin section analysis. Dissolution experiments, core flooding experiments, and CT scanning were used to investigate the increased permeability and changes in the pore structure of the cores during acidification. The minerals in the rocks are primarily plagioclase, kalifeldspar, and quartz, with trace amounts of calcite, chlorite, magnetite, illite, biotite, hornblende, sphene, and sericite. At 80°C and 10 mL of main acid injection, polyhydrogen chelating acid (6% HCl + 5% SA601 + 7% SA701) improved granite permeability more than mud acid (8% HCl + 2% HF) and fluoroboric acid (8% HCl + 8% HBF4), with permeability increase of 3.68. The CT three-dimensional images of the rocks show that both the cores acidified with polyhydrogen chelating acid and mud acid formed continuous acid-etched wormholes, while the cores acidified with fluoroboric acid did not. Compared to the mud acid, the core acidified by the polyhydrogen chelating acid produced more visible acid-etched wormholes. Meanwhile, the polyhydrogen chelating acid was more effective at improving the pore throats and expanding the flow channels in the core. This study serves as a reference for the application of acidification and increasing production in low-permeability granite reservoirs.

Aging damage characteristics of acid‐etched sandstone samples

AbstractTo investigate the erosive damage effect of the acidic solution on sandstone, experiments were conducted to examine the macro‐ and micro‐characteristics of sandstone samples under different acid etching times. Microscopic morphology changes, pore structure characteristics, mineral composition changes, and mechanical response characteristics were obtained before and after acid etching. Finally, a comprehensive evaluation index for acid etching damage was proposed. The results show that: (1) Acidic solution will erode the sandstone skeleton and cause the sandstone to collapse. The etched surface appears “flocculent” and yellow sediment is produced. (2) The pores in sandstone samples are mainly micro‐ and mesopores, and the total porosity increases exponentially with the duration of acid etching. The volume fraction of micropores can reach up to 81.5%. (3) The acid etching process of sandstone samples includes physical diffusion and chemical dissolution, which can be divided into four stages and three regions from the outside to the inside. After acid etching, the uniaxial compression failure mode of the sample changes from shear to mixed shear‐tensile failure. (4) The comprehensive evaluation index based on three failure modes generated during the loading process shows good consistency with the overall changes of characteristics parameters such as elastic modulus, peak stress, and peak strain. The research findings of this paper can provide theoretical support for the assessment of rock mass stability and disaster prevention in acidic environments.

Insights into the pore structure effect on the mass transfer of fuel cell catalyst layer via combining machine learning and multiphysics simulation

Analysis of the catalytic layer (CL) pore structure and three-phase (electron phase, proton phase, and reactant phase) mass transfer in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) is critical for improving concentration polarization and optimizing performance. However, there is a lack of studies on the pore structure’s impact on the catalytic layer three-phase mass transfer. In this work, the influence of pore structure on catalytic layer three-phase mass transfer and multiphysics distribution was investigated by combining machine learning and multiphysics simulation. Among many key factors investigated by machine learning that impact the performance of catalytic layer, porosity emerges as the primary influencing factor. Porosity accounts for 32.7 % of the electric potential drop, with macro/micro porosity contributing 27.6 % and 5.1 %, and 32.8 % of the current density, with macro/micro porosity contributing 15.6 % and 17.2 %. Furthermore, the macropore structure has a much greater influence on the performance of the catalytic layer compared to the micropore structure. Moreover, the simulation results demonstrated that porosity has a great influence on three-phase mass transfer, the oxygen molarity increases with increasing porosity. The electric potential difference increases exponentially as porosity increases. The relationship between current density and porosity is a volcanic relationship, which can be expressed as a quadratic polynomial function. The mesoscopic pore-scale model (PSM) with an εeff of 0.502 (εmic of 0.2 and εmac of 0.378) exhibits the highest mean current density at 619.526 mA/cm2@0.5 V, attributed to a more uniform and efficient three-phase transfer path. The accuracy of the mesoscopic pore-scale model and the polynomial equation is further confirmed through corresponding experiments. The experiment results show that the current density decreased as the εeff increased from 0.682 to 0.702, which aligns with the theoretical predictions of the PSM model and polynomial equation. These studies are valuable for comprehending the internal three-phase mass transfer behavior and optimizing the catalytic layer pore structure to enhance HT-PEMFC performance.

Superior filaments-based fabric with thermal-mechanical-electrical coupling properties for remote temperature alarm

The safeguarding fabrics featuring good thermal insulation, flame retardancy, and force dissipation simultaneously remain challenging due to the current filaments with limited properties. Herein, a novel and flame-retardant filament (F-filament) is developed by hot-extruding the mixture of shear stiffening gel/thermoplastic polyurethane (SSG/TPU) and microencapsulated ammonium polyphosphate (MHAPP), which is conducive to knitting protective fabrics. The conductive F-filament (cF-filament) is further prepared by incorporating with MXene. The F-filament-based fabrics present better anti-impact properties than commercial fabrics and can dissipate 6.32 kN impacting force to 1.89 kN. The patterned knitted fabric also facilitates heat exchange, reducing the contact temperature of the body surface to approximately 37 °C when exposed to an 80 °C heat source, effectively avoiding thermal damage through its porous structure. Moreover, the F-filament-based fabrics are intact even after 19 s of continuous burning. Notably, the cF-filament is demonstrated for use as a sensor for real-time multimodal monitoring, such as detecting external mechanical loadings and temperature stimuli. The cF-filament sensor can be integrated into the F-filament-based knitted fabrics, which accurately realizes environmental monitoring and explores the best-escaping route through a remote temperature alarm system.

Novel oxygen vacancies-rich 3D porous ZnO for highly sensitive 3-hydroxy-2-butanone biomarker gas sensors

Listeriosis can cause human death via infection by Listeria monocytogenes (LMs) with a high fatality rate of 20–30 %. Detection of 3-hydroxy-2-butanone (3H-2B) biomarker of LMs can achieve estimation of LMs content, which is of great significance for human health. Exploring porous metal oxide semiconductors (MOSs) with rich vacancies towards 3H-2B sensing is quite promising for achieving this goal. Herein, we report a highly sensitive 3H-2B sensor based on novel 3D porous ZnO with rich oxygen vacancies which was facilely obtained by sacrificing Zn foam in oxalic acid and subsequent thermal decomposition. The ZnO sensor displays ultrahigh sensor response of Ra/Rg = 328@5 ppm, super-low detection limit of 0.001 ppm, excellent cycling stability and selectivity and good linear response at 120 °C, showing great potential for precise detection of 3H-2B biomarker. The porous structure and increased oxygen vacancies contribute greatly to the adsorption of active oxygen species therefore the sensing reactions on ZnO surface, which accounts for the high sensing performance. Our work provides an ingenious strategy to produce novel 3D ZnO with rich oxygen vacancies as well as new insights for boosting the detection of LMs.

Development of Polyvinyl Alcohol Hydrogels for Controlled Glucose Release in Biomedical Applications.

Polyvinyl alcohol (PVA) hydrogels have a wide range of applications in the pharmaceutical and biomedicine fields due to their exceptional biophysical properties. The study focuses on preparing and characterizing capsule-shaped PVA hydrogels to enhance their biocompatibility and porosity for controlled glucose release and cell proliferation. The hydrogels were prepared using different concentrations (Cs) and molecular weights (MWs) of PVA, with two different lengths, A (10 mm) and B (20 mm), to control glucose release over 60 min. The preparation process involved PVA gel preparation and PVA hydrogel formation. A total of 500 µL of glucose was injected into all dehydrated hydrogels in groups A and B. Glucose release was studied by immersing the hydrogels in saline at 37 °C with stirring at 500 rpm. The SUP-B15 cell line was grown in six A1 hydrogels for biocompatibility testing. The results indicate that all hydrogels remained stable at 37 °C without degrading. Those with a higher C and MW exhibited a denser and less porous structure, lower glucose storage capacity, and higher elongation at break. Significant differences in glucose release, diffusion speed, and flux were observed, which were more evident in A1 > A4, B1 > B4, and B1 > A1 over 60 min. A1 and B1 had higher values because their higher porosity distribution allowed glucose to diffuse more easily. B1, being larger, has more glucose due to its increased length. The cell growth response and viability at 48 h in contact with the hydrogels was similar to that of the control (4.5 × 105 cells/mL, 98.5% vs. 4.8 × 105 cells/mL, 99.7% viability), thus demonstrating biocompatibility. The hydrogels effectively released glucose over 60 min, with variations based on porosity, C, MW, and length, and demonstrated good biocompatibility with the cell line.

Biomass-Derived-Carbon-Supported Spinel Cobalt Molybdate as High-Efficiency Electrocatalyst for Oxygen Evolution Reaction.

Ananas comosus leaves were converted to a porous graphitized carbon (GPLC) material via a high-temperature pyrolysis method by employing iron salt as a catalyst. A cobalt molybdate (CoMoO4)-and-GPLC composite (CoMoO4/GPLC) was then prepared by engineering CoMoO4 nanorods in situ, grown on GPLC. N2 adsorption-desorption isothermal curves and a pore size distribution curve verify that the proposed composite possesses a porous structure and a large specific surface area, which are favorable for charge and reactant transport and the rapid escape of O2 bubbles. Consequently, the as-synthesized CoMoO4/GPLC shows low overpotentials of 289 mV and 399 mV to afford the current densities of 10 mA cm-2 and 100 mA cm-2 towards the oxygen evolution reaction (OER), which is superior to many CoMoO4-based catalysts in previous studies. In addition, the decrease in current density is particularly small, with a reduction rate of 3.2% after a continuous OER procedure for 30 h, indicating its good stability. The excellent performance of the CoMoO4/GPLC composite proves that the GPLC carrier can obviously impel the catalytic activity of CoMoO4 by improving electrical conductivity, enhancing mass transport and exposing more active sites of the composite. This work provides an effective strategy for the efficient conversion of waste ananas comosus leaves to a biomass-derived-carbon-supported Co-Mo-based OER electrocatalyst with good performance, which may represent a potential approach to the development of new catalysts for OER, as well as the treatment of waste biomass.