Moderate Surface Research Articles

Support induced effects on the activity and stability of Ga2O3 based catalysts for the CO2-assisted oxidative dehydrogenation of propane

The influence of the support nature (Al2O3, TiO2, SiO2) on the activity and stability of supported Ga2O3 (10 wt%) catalysts was investigated for the production of propylene through the CO2-assisted oxidative dehydrogenation of propane (CO2-ODP). Catalytic activity was found to be higher when gallium oxide was dispersed on alumina support which was characterized by the highest acid site density and moderate surface basicity. Below 650 °C propylene yield increased in the order Ga2O3-TiO2<Ga2O3-SiO2<Ga2O3-Al2O3, which was modified as Ga2O3-Al2O3<Ga2O3-TiO2<Ga2O3-SiO2 for higher reaction temperatures. Propylene selectivity decreased with increasing reaction temperature followed by an increase of ethylene and methane selectivity implying that the side reactions of propane hydrogenolysis and propane/propylene decomposition were facilitated at higher temperatures hindering the CO2-ODP reaction. Gallium oxide catalysts supported on TiO2 and SiO2 exhibited sufficient stability for 30-35 hours on stream at 660 and 710 οC, contrary to Ga2O3-Al2O3 which although was stable at 710 οC it was gradually deactivated when the reaction was taking place at 600 °C. Temperature programmed oxidation experiments showed that carbon deposition was favored over Ga2O3-Al2O3 catalyst when the reaction was conducted at low temperature, which may be related to the higher surface acidity of this sample and be responsible for its deactivation with time. SEM images and elemental mapping obtained from both the freshly prepared and used Ga2O3-MxOy samples showed that Ga and M (M: Si, Ti, Al) were uniformly present even after prolonged catalyst interaction with the reaction mixture. EDS analysis indicated that carbon formation was accelerated with increasing reaction temperature.

Synergistic effects of deep eutectic solvents on the morphology and performance of polysulfone ultrafiltration membranes

This study investigates the synthesis of flat sheet asymmetric Polysulfone (PSF) membranes using the Non-Solvent Induced Phase Separation (NIPS) method, enhanced by incorporating Deep Eutectic Solvents (DES) composed of Choline Chloride (ChCl) and DL-Malic Acid (MA). The research explores the individual and combined effects of ChCl and MA on membrane morphology and performance. Comprehensive characterization techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy-Universal Attenuated Total Reflectance (FTIR-UATR), and Atomic Force Microscopy (AFM), were employed to analyze the structural and surface properties of the membranes. Key performance metrics such as Pure Water Permeability (PWP), protein and dye rejection, fouling behavior, porosity, surface hydrophilicity, and mechanical strength were evaluated. Results demonstrated that integrating DES into the PSF matrix significantly improved membrane properties. The 3% DES membrane exhibited the highest Pure Water Permeability (PWP) of 186.82 L/m2h/bar, the lowest water contact angle of 68.8°, and optimal balance in surface roughness parameters, leading to superior antifouling properties with high flux recovery ratio (FRR) and balanced reversible (Rr) and irreversible fouling (Rir) components. The ChCl (HBA) membrane displayed a notable PWP of 121.62 L/m2h/bar, large pore sizes (42.72 nm), and moderate surface roughness (Ra of 3.32 nm). In contrast, the MA (HBD) membrane demonstrated the highest hydrophilicity with the lowest contact angle (70.7°) and a compact, robust structure, despite its smallest pore sizes and lack of permeability. The findings underscore the synergistic effect of DES formation in the membrane, improving overall performance for ultrafiltration applications. This study provides valuable insights into the distinct roles of ChCl as an HBA and MA as an HBD in DES-modified PSF membranes, revealing their individual contributions and the importance of optimizing DES components and concentrations for specific filtration applications.

Efficacy of Amniotic Membrane Grafting for the Treatment of Chemical and Thermal Ocular Surface Injuries: A Report by the American Academy of Ophthalmology

To evaluate the published literature on the efficacy of amniotic membrane grafting (AMG) in the management of acute chemical and thermal ocular surface burns with respect to the rate of corneal re-epithelialization and improvement of visual acuity or corneal clarity. Literature searches were conducted in the PubMed database in May 2023 and updated in January 2024 and were limited to the English language without date restrictions. The searches yielded 474 citations; 58 were reviewed in full text, and 9 met the inclusion criteria. Four studies were rated level II, and 5 studies were rated level III. This assessment focuses on 3 level II articles that provided consistent primary and secondary outcomes but demonstrated suboptimal study design with respect to power calculations and lacked a priori sample-size calculations. Amniotic membrane grafting significantly improved corneal re-epithelialization compared with medical therapy alone in eyes with moderate-grade burns. For severely burned eyes, AMG demonstrated no advantage over medical therapy. Additionally, AMG demonstrated no significant advantage over medical therapy for improved visual acuity or corneal clarity for moderate or severe ocular surface burns. The best available level II evidence suggests that AMG in the setting of acute ocular surface burns has efficacy in hastening re-epithelialization in moderate burns. As an adjuvant to medical therapy, it did not demonstrate a benefit in improving re-epithelialization in severe burns or visual acuity or corneal clarity in either moderate or severe burns. Proprietary or commercial disclosure may be found after the references.

N-doped Porous Carbon Derived from the Pyrolysis of a Polydopamine-coated Hypercross-linked Polymer for Enhanced CO2 Adsorption.

Porous carbon materials can simultaneously capture and convert carbon dioxide, helping to reduce greenhouse gas emissions and using carbon dioxide as a feedstock for the production of valuable chemicals or fuel. In this work, a series of N-doped porous carbons (PDA@HCP(x:y)-T) was prepared; the CO2 adsorption capacity of the prepared PDA@HCP(x:y)-T was enhanced by coating polydopamine (PDA) on a hypercross-linked polymer (HCP) and then adjusting the mass ratio of PDA to HCP and the carbonization temperature. The results showed that the prepared PDA@HCP(1:1)-850 exhibited a high CO2 adsorption capacity due to abundant micropores (0.6762 cm3/g), a high specific surface area (1220.8 m²/g), and moderate surface nitrogen content (2.75%). Notably, PDA@HCP(1:1)-850 exhibited the highest CO2 uptake of 6.46 mmol/g at 0 °C and 101 kPa. Critically, these N-doped porous carbons can also be used as catalysts for the reaction of CO2 with epichlorohydrin to form chloropropylene carbonate, with chloropropylene carbonate yielding up to 64% and selectivity of the reaction reaching 94%. As a result, these N-doped porous carbons could serve as potential candidates for CO2 capture and conversion due to their high reactivity, excellent CO2 uptake, and good catalytic performance.

Morphology and crystal–plane dependent catalytic activity of α-Fe2O3 for NH3-SCR de-NOx: Experimental and DFT study

Three kinds of α-Fe2O3 catalysts, each having a distinct morphology and crystal planes, were synthesized and applied for NH3-SCR reaction. The morphology and crystal-plane effects for the activity of α-Fe2O3 were investigated by a combined study of experiment and density functional theory. The experiment findings reveal that the α-Fe2O3-S, α-Fe2O3-R, and α-Fe2O3-C display the shuttle (predominantly exposed (110) and (012) crystal planes), rod (predominantly exposed (110), (104), and (012) crystal planes), and cube (only exposed (104) crystal plane) shapes, respectively. Furthermore, the α-Fe2O3-S yields the best catalytic performance because of its moderate surface acidity, the best redox capacity, and the highest contents of surface Fe3+ and chemisorbed oxygen, which may result from the morphology and crystal plane effects. Additionally, the activity of different crystal planes is significantly different. The NO and NH3 are more apt to be adsorbed on the (110) and (012) surfaces and O2 dissociation is more likely to happen on the (110) surface. Besides these, the (110) surface owns the lowest energy barrier to the decomposition of intermediate NH2NO. All of the mentioned above collectively enhance the efficiency of the SCR process. Finally, the (110) and (012) surfaces facilitate the rapid SCR process, while the (104) surface is the most difficult. The α-Fe2O3-S predominately exposes high activity of (110) and (012) surfaces, therefore, it can yield the highest catalytic activity.

Investigating ingredient influence on reconstitution of powdered cocoa beverage via constrained mixture design

Reconstitution of a powdered cocoa beverage (PCB) produced by wet-mixing and oven-drying were studied. Sixteen PCB samples with different proportions of core ingredients, namely cocoa (5–25 %), skimmed milk (10–50 %), hydrolysed cereal extract (15–60 %), sucrose (0–30 %) and palm olein (0–15 %), were generated via a constrained mixture design. PCB samples had varying physical properties which included bulk porosity (57.3–74.8 %), particle surface hydrophilicity (contact angle = 60.0–94.5°) and glass transition temperature (51.2–86.3 °C). Consequently, PCB samples differed in reconstitution properties like wetting time (11–>300 s), reconstitution time (14–141 s) and soluble content (51.3–86.8 %). Subsequently, mixture regression models were developed to varying success (adjusted R2 = 70–97 %) for identifying the influence of each core ingredient on physical and reconstitution properties of PCB. PCB wettability was most improved by increasing the proportion of hydrolysed cereal extract, through forming powders with moderate particle surface hydrophilicities but higher glass transition temperatures and higher bulk porosities. Conversely, PCB wettability became exceptionally poor when it contained >35 % skimmed milk and <5 % palm olein. Additionally, a higher ratio of protein-rich skimmed milk against carbohydrate-rich hydrolysed cereal extract and sucrose led to solubility loss in PCB.

Porous Iron Electrodes Reduce Energy Consumption During Electrocoagulation of a Virus Surrogate: Insights into Performance Enhancements Using Three-Dimensional Neutron Computed Tomography.

Electrocoagulation has attracted significant attention as an alternative to conventional chemical coagulation because it is capable of removing a wide range of contaminants and has several potential advantages. In contrast to most electrocoagulation research that has been performed with nonporous electrodes, in this study, we demonstrate energy-efficient iron electrocoagulation using porous electrodes. In batch operation, investigation of the external pore structures through optical microscopy suggested that a low porosity electrode with sparse connection between pores may lead to mechanical failure of the pore network during electrolysis, whereas a high porosity electrode is vulnerable to pore clogging. Electrodes with intermediate porosity, instead, only suffered a moderate surface deposition, leading to electrical energy savings of 21% and 36% in terms of electrocoagulant delivery and unit log virus reduction, respectively. Neutron computed tomography revealed the critical role of electrode porosity in utilizing the electrode's internal surface for electrodissolution and effective delivery of electrocoagulant to the bulk. Energy savings of up to 88% in short-term operation were obtained with porous electrodes in a continuous flow-through system. Further investigation on the impact of current density and porosity in long-term operation is desired as well as the capital cost of porous electrodes.

Intercomparison of multisource actual evapotranspiration satellite products in Bilate watershed, Ethiopia

Recent advancements in satellite remote sensing have led to increased spatial and temporal resolution of actual evapotranspiration (AET) estimates across scales. Yet, the accuracy of AET products remains unknown for many regions, prompting further investigation to guide selection. This study intercompares five AET products within Ethiopia’s Bilate watershed, focusing on the 2009-2018 period. The products assessed include TerraClimate, Food and Agriculture Organization Water Productivity (FAO WaPOR), Moderate Resolution Imaging Spectroradiometer Operational Simplified Surface Energy Balance (ModisSSEBop), and Synthesis of Global AET. Reference evapotranspiration estimated using ground station climate data served as a basis for comparing the Satellite Products (SP). The intercomparison was conducted using descriptive statistics, scatter plots and Pearson’s Correlation Coefficient to assess correlation, standard deviation, and root mean square error. Additional error statistics were also considered. Findings reveal higher AET values in the highlands compared to the lowlands of the Bilate watershed. A weak correlation (&lt;0.35) exists between ETo and satellite-derived AET, potentially due to the averaging of AET values across diverse land cover classes, contrasting with point-scale reference measurements. The variance among AET products was varied across seasons and elevation ranges. While the annual patterns of AET were consistent across the products, large discrepancies in magnitude (average AET varies from 25 to 83 mm per month in the lower part) were detected. The ModisSSEBop global and continental products showed minimal mismatches, whereas the Synthesis of Global and FAO WaPOR products displayed slight differences. Notably, the FAO WaPOR’s AET estimates showed relatively closer agreement with many products in terms of magnitude and variability of AET. In conclusion, the study highlights significant random and systematic differences between the AET products. The substantial mismatch between the products underscores the necessity for continued research to refine AET product accuracy through improved input dataset and revisiting the algorithms.

Electromechanical response of multilayer graphene sheet/polypropylene nanocomposites and its relationship with the graphene sheet physicochemical properties

Abstract The mechanical, electrical, and piezoresistive responses of multilayer graphene sheet (GS)/polypropylene (PP) nanocomposites are investigated using four GSs of distinctive physicochemical properties. It is found that the morphology of the interconnected network of GS agglomerates at the mesoscale governs the mechanical, electrical, and electro-mechanical (piezoresistive) properties of the PP nanocomposites. The morphology of the mesoscale network of electroconductive fillers governs the effective properties of the nanocomposite. This network morphology strongly depends on the GS lateral size, dispersion, agglomeration, and, to a lesser extent, the specific surface area of the GSs. Within the range of lateral sizes investigated herein (1 - 21 m), larger GSs yields nanocomposites with higher electrical conductivity. On the other hand, GSs of moderate lateral size (~ 6.5 m) and specific surface area of ~ 141 m2/g render GS/PP nanocomposites with a more dispersed and more sparsely interconnected network. This better dispersed network with agglomerates of smaller dimensions is concomitant with improved stiffness and strength, and higher gauge factors (~ 18.2) for this GS/PP nanocomposites. Excellent capabilities for detection of human motion were proved for these nanocomposites.

Dependence of dense filament frontogenesis in a hydrostatic model

In this study, a hydrostatic model - the Navy Coastal Ocean Model (NCOM) is used to analyze the temporal evolution of a cold filament under moderate wind (along / cross filament) and surface cooling forcing conditions. The experimental framework adhered to the setup used in large eddy simulations by Sulllivan and McWilliams (2018). For each forcing scenario, the impact of horizontal resolutions is systematically explored through varies model resolutions of 100 m, 50 m, and 20 m; and the influence of horizontal mixing is investigated by adjusting the Smagorinsky constant within the Smagorinsky horizontal mixing scheme. The role of surface gravity waves is also assessed by conducting experiments both with and without surface wave forcing.The outcomes of our study revealed that while the hydrostatic model is able to predict the correct characteristics/physical appearance of filament frontogenesis, it fails to capture the precise dynamics of the phenomenon. Horizontal mixing parameterization in the model was found to have marginal effect on frontogenesis, and the frontal arrest is controlled by the model's subgrid-scale artificial regularization procedure instead of horizontal shear instability. Consequently, higher resolution is corresponding to stronger frontogenesis in the model. Thus, whether the hydrostatic model can produce realistic magnitude of frontogenesis is purely dependent on the characteristic of the front/filament simulated and model resolution. Moreover, examination of the parameterized effect of surface gravity wave forcing through vertical mixing unveiled a limited impact on frontogenesis, suggesting that the parameterization falls short in representing the real physics of wave-front interaction.

Covalent Organic Framework Catalyzed Amide Synthesis Directly from Alcohol Under Red Light Excitation.

The dehydrogenative coupling of alcohols and amines to form amide bonds is typically catalysed by homogeneous transition metal catalysts at high temperatures ranging from 130-140 °C. In our pursuit of an efficient and recyclable photocatalyst capable of conducting this transformation at room temperature, we report herein a COF-mediated dehydrogenative synthesis. The TTT-DHTD COF was strategically designed to incorporate a high density of functional units, specifically dithiophenedione, to trap photogenerated electrons and effectively facilitate hydrogen atom abstraction reactions. The photoactive TTT-DHTD COF, synthesized using solvothermal methods showed high crystallinity and moderate surface area, providing an ideal platform for heterogeneous amide synthesis. Light absorption by the COF across the entire visible range, narrow band gap, and valence band position make it well-suited for the efficient generation of excitons necessary for targeted dehydrogenation. Utilizing red light irradiation and employing extremely low loading of the COF, we have successfully prepared a wide range of amides, including challenging secondary amides, in good to excellent yields. The substrates' functional group tolerance, very mild reaction conditions, and the catalyst's significant recyclability represent substantial advancements over prior methodologies.

Covalent Organic Framework Catalyzed Amide Synthesis Directly from Alcohol Under Red Light Excitation

AbstractThe dehydrogenative coupling of alcohols and amines to form amide bonds is typically catalysed by homogeneous transition metal catalysts at high temperatures ranging from 130–140 °C. In our pursuit of an efficient and recyclable photocatalyst capable of conducting this transformation at room temperature, we report herein a COF‐mediated dehydrogenative synthesis. The TTT‐DHTD COF was strategically designed to incorporate a high density of functional units, specifically dithiophenedione, to trap photogenerated electrons and effectively facilitate hydrogen atom abstraction reactions. The photoactive TTT‐DHTD COF, synthesized using solvothermal methods showed high crystallinity and moderate surface area, providing an ideal platform for heterogeneous amide synthesis. Light absorption by the COF across the entire visible range, narrow band gap, and valence band position make it well‐suited for the efficient generation of excitons necessary for targeted dehydrogenation. Utilizing red light irradiation and employing extremely low loading of the COF, we have successfully prepared a wide range of amides, including challenging secondary amides, in good to excellent yields. The substrates’ functional group tolerance, very mild reaction conditions, and the catalyst's significant recyclability represent substantial advancements over prior methodologies.

Exploring oxygen migration and capacitive mechanisms: Crafting oxygen-enriched activated carbon fiber from low softening point pitch

A green pitch fiber from coal tar distillation residue, with a softening point of 190 °C, was used to make activated carbon fiber through an in-situ oxygen-doped method. Oxygen-rich pitch-based activated carbon fibers (OPACFs) were successfully created with a three-stage stabilization process using this low softening point pitch fiber. The OPACFs exhibit a moderate pore size distribution and high surface oxygen content (20.83 at%). The migration and transformation of oxygen during this process were studied. Due to the formation of stable oxygen-containing functional groups (CO), the resulting material shows excellent electrochemical performance. It achieved a specific capacitance of 334 F/g at 0.5 A/g and maintained good rate capacity (73.7 %, 0.5–50 A/g) in a 6 M KOH electrolyte. The assembled supercapacitor displayed exceptional cycle stability, retaining 91.4 % capacitance at 1 A/g after 10,000 cycles. Further investigation revealed that the specific capacitance includes both surface-controlled and diffusion-controlled capacitance, with oxygen doping significantly enhancing the latter.

Quality of Life and Its Associated Factors Among Patients with Psoriasis Attending the Dermatology Department at Public Hospitals in Harar Town, Eastern Ethiopia

&amp;lt;i&amp;gt;Background&amp;lt;/i&amp;gt;: Psoriasis is a skin disorder that inflames the skin and joints, increasing susceptibility to obesity, heart disease, and diabetes. It is more common in higher-altitude areas and affects 100 million people worldwide. Understanding the subtypes and treatments is crucial for the management of the condition. &amp;lt;i&amp;gt;Method&amp;lt;/i&amp;gt;: The study used a cross-sectional design to assess quality of life and identify factors associated with poor quality of life among patients with psoriasis in the region. The study involved 219 patients. Data collection was carried out through structured interviews with patients with psoriasis attending public hospitals in Harar, eastern Ethiopia. Bivariate and multivariate logistic regression analyzes were performed to identify factors associated with poor quality of life among patients with psoriasis. Variables demonstrating a p-value &amp;gt; 0.20 in bivariate analyzes were included in the multivariate logistic regression model. Statistical significance was determined with a p-value &amp;lt; 0.05. &amp;lt;i&amp;gt;Results&amp;lt;/i&amp;gt;: the proportion of poor quality of life was 54.8%. Factors associated with poor quality of life could not read and write (AOR = 14, 95% CI 2.08, 94.2), Duration of more than 5 years (AOR = 3.1, 95% CI 1.49, 6.41), New body site and in disease patients at both sites (AOR = 9.2, 95% CI 2.96, 28.56) and (AOR = 7.2, 95% CI 2.37, 21.95), respectively. Moderate affected body surface area (AOR= 2.98, 95% CI 1.15, 6.41)). And have a comorbidity (AOR= 2.69, 95%CI: 1.01, 7.20). &amp;lt;i&amp;gt;Conclusions&amp;lt;/i&amp;gt;: The study revealed that 54.8% of the patients experienced severe quality of life impairment, with factors such as illiteracy, duration of the disease over five years, psoriasis at new sites of the body, moderate body surface area affected, and comorbidities significantly associated with poor quality of life. The study shed light on the challenges faced by patients with psoriasis in Harar, highlighting the need for comprehensive care strategies to improve their quality of life and well-being.

Insights into Si/Al ratios for enhanced performance of β-zeolites in thermocatalytic cracking of crude oil to light olefins

The escalating demand for key petrochemicals, particularly ethylene and propylene, underscores the critical need for proficient catalysts in crude oil conversion processes. Attaining high propylene selectivity necessitates catalysts with superior adsorption capacity, thermal stability, moderate surface acidity, and pores large enough to facilitate the diffusion of larger crude oil molecules. In the present study, three different BEA Zeolites (β-zeolite) catalysts were successfully synthesized by hydrothermal method and used for catalytic cracking of Arabian Light crude oil to produce valuable petrochemical products, such as propylene, ethylene, and naphtha. The catalysts were characterized using 27Al and 29Si NMR, NH3-TPD, BET, XRD, TGA, FTIR, XRF, and FE-SEM. The thermocatalytic cracking of Arabian Light crude oil was evaluated in a fixed-bed microactivity test (MAT) unit between 550 and 600 °C. The as-prepared β-zeolite with a Si/Al ratio of 50 exhibited better catalytic activity in the catalytic cracking of Arabian Light crude oil compared to counterparts with Si/Al ratios of 35 and 65, This superiority can be attributed to its optimal combination of surface acid site distribution, textural properties, surface morphology, and high adsorption capacity. The highest feed conversion (83.4 %) and selectivity to propylene (16.11 %) were attained using β-zeolite with a Si/Al ratio of 50 at 600 °C. Importantly, our findings suggest that these catalysts hold significant potential, rivalling primary MFI catalysts like ZSM-5 commonly employed in similar reactions. This underscores their promise as catalysts of choice in the realm of catalytic cracking processes, paving the way for advancements in petrochemical production.

Metal‐Decorated Porous Organic Polymers: Bridged the Gap between Organic and Inorganic Scaffolds†

Comprehensive SummaryAdvanced functionalization‐decorated porous organic polymers (POPs) are emerging as a prominent research focus, spanning from their construction to applications in gas storage and separation, catalysis, energy storage, electrochemistry, and other areas. Furthermore, the inherent organic nature, tailored pore structures, and adjustable chemical components of POPs offer a versatile platform for the incorporation of various metal active sites. Meticulously designed molecular building blocks can serve as organic ligands uniformly distributed throughout POPs, leading to the effective isolation of inorganic metal active sites at the molecular level. In this manner, POPs containing active metal centers bridge the gap between organic and inorganic scaffolds. This review aims to provide an overview of recent research progress on metal‐decorated POPs, focusing on strategies for incorporating metal active sites into POPs and their applications in adsorption, separation, catalysis, and photoelectrochemistry. Finally, current challenges and future prospects are discussed for further research. Key ScientistsAdvanced functionalized porous organic polymers have become a new research hotspot, ranging from their construction to their use in gas storage and separation, catalysis, energy storage, electrochemistry, and other applications. In 2002, the McKeown group was the first to report phthalocyanine‐based MPOPs with permanent porosity and a moderate surface area. In 2010, the Yu group prepared nanoporous polyporphyrin materials P(Fe‐TTPP) from the metallated porphyrin with functionalized thiophenyl groups by the FeCl3 catalyzed oxidation couple reaction showing the surface area of 1522 m2·g–1. Subsequently, in 2013, the Deng group was the first to use metalated salens as the original building blocks for preparing MPOPs. The Morin group was the first to produce a series of ferrocene‐based nanoporous frameworks via radical polymerization, with surface areas ranging from 385 to 899 m2·g–1. In 2016, the Han group synthesized two N‐pyridinylphenylcarbazole (PPC) ligands to produce a series of metalized polycarbazole networks. Recently, the Tan group reported a solvent‐knitting hyper‐cross‐linking reaction to produce HUST‐1, which contains a porphyrin unit. The porphyrin moiety provides a centered square‐planar metal post‐coordination site, resulting in the metalated HUST‐1‐Co, which exhibits high efficiency in the catalytic conversion of CO2. Additionally, the Kegnæs group combined the decomposition of the palladium complex with an in situ catalyzed polymerization reaction, enabling the confinement of nascent Pd particles in the developing polymer network. This review focuses on recent research progress in metal‐decorated POPs, emphasizing strategies for incorporating metal active sites into POPs and their applications.

Dense graphene composite hydrogels as advanced electrode materials for high-performance supercapacitors

In this work, alanine functionalized nanocellulose/graphene composite hydrogels (NCGHalas) were prepared via an easy hydrothermal reaction using alanine, GO, and nanocellulose as reactant. Thanks to this synthesis strategy, NCGHalas exhibited large bulk density, abundant heteroatom functional groups, reasonable porous structure and moderate specific surface area. Based on the above characteristics, the aqueous symmetric supercapacitors (ASSC) assembled by NCGHala25 presented high gravimetric and volumetric specific capacitance of 276.5 F g−1 and 320.8 F cm−3 at 0.3 A g−1, excellent rate performance (77.9 % at 10 A g−1), and long working life of 95.4 % retention after 10,000 cycles at 10 A g−1. Furthermore, the NCGHala25 based ASSC also exhibited large gravimetric and volumetric specific energy densities of 9.6 Wh kg−1 and 11.1 Wh L−1. More importantly, the flexible solid-state supercapacitors (FSSC) fabricated by NCGHala25 and PVA-KOH electrolyte delivered high specific capacitance (178.2 F g−1, 0.3 A g−1), and this value can be maintained for 74.2 % even at 10 A g−1.

Enhanced dielectric properties of nanocomposites with cyanoethyl cellulose and core‐shell structured BaTiO3@Al2O3 fillers

AbstractThe interface between the polymer matrix and inorganic fillers plays a determinative role in dielectric properties of the composites. In this work, dielectric composites containing core‐shell structured BaTiO3@Al2O3 (BT@AO) nanoparticles and cyano functionalized cellulose (cyanoethyl cellulose, CEC) were prepared to achieve enhanced interface and dielectric properties. With the wide bandgap Al2O3 (AO) shell, the carrier motion inspired by elevating electric filed and temperature was significantly impeded in the composites. Meanwhile, the moderate dielectric constant and surface energy of AO shell between CEC and BaTiO3 (BT) alleviated the inhomogeneous local electric field distribution and improve the interfacial compatibility between inorganic filler and CEC matrix. As a result, enhanced dielectric properties including restrained dielectric loss (0.23 for BT@AO/CEC versus 0.51 for BT/CEC at 100 Hz), suppressed conductivity, increased breakdown strength and improved dielectric constant were accessed in the BT@AO/CEC composites. The excellent thermal conductivity of AO also offered the composites with additional advantage of low electrical conductivity at high temperature of 100°C (1.56 × 10−10 S/cm) exhibiting two orders of magnitude smaller than that of pure CEC.Highlights Core‐shell structured BaTiO3@Al2O3 were prepared and incorporated into cyanoethylated cellulose to yield flexible nanocomposites. Carrier motion was significantly restricted by the wide band gap of Al2O3 shell. Enhanced interfacial compatibility was accessed in the BaTiO3@Al2O3/CEC composite. Improved dielectric properties and thermal conductivity were achieved.

Efficient removal of Chromium(VI) from wastewater based on magnetic multiwalled carbon nanotubes coupled with deep eutectic solvents

Industrial wastewater containing heavy metal Cr(VI) seriously affects the health of organisms and may even lead to cancer. Developing efficient adsorbents that can quickly separate heavy metals is crucial for treating wastewater. In this study, magnetic multiwalled carbon nanotubes (MMWCNTs) with moderate particle size and abundant surface active sites were prepared by coating multiwalled carbon nanotubes with magnetic nanoparticles. The results of FTIR, XRD, TG, VSM, BET, and EDS showed MWCNTs completely encapsulated on the surface of the magnetic nanoparticles, with a particle size of approximately 30 nm. Oxygenated groups provided abundant surface active sites and formed numerous mesopores. The response surface methodology was used to optimize the adsorbent dose, adsorption contact time and adsorption temperature, and the removal rate of Cr(VI) was more than 95%. The quasi-second order kinetics and Freundlich adsorption isotherm model explained the adsorption process to Cr(VI). MMWCNTs interacted with Cr(VI) through electrostatic attraction, reduction reactions, complexation, and other means. The extensive hydrogen bonding of the green solvent deep eutectic solvent (DES) was employed to desorb the MMWCNTs and desorption rate exceed 90%. Even after five adsorption-regeneration cycles, the adsorbent maintained a high capacity. In conclusion, these novel MMWCNTs, as efficient adsorbents paired with DES desorption, hold broad potential for application in the treatment of Cr(VI)-contaminated wastewater.

Study of the Suitability of Corncob Biochar as Electrocatalyst for Zn–Air Batteries

There has been a recent increasing interest in Zn–air batteries as an alternative to Li-ion batteries. Zn–air batteries possess some significant advantages; however, there are still problems to solve, especially related to the tuning of the properties of the air–cathode which should carry an inexpensive but efficient bifunctional oxygen reduction (ORR) and oxygen evolution (OER) reaction electrocatalyst. Biochar can be an alternative, since it is a material of low cost, it exhibits electric conductivity, and it can be used as support for transition metal ions. Although there is a significant number of publications on biochars, there is a lack of data about biochar from raw biomass rich in hemicellulose, and biochar with a small number of heteroatoms, in order to report the pristine activity of the carbon phase. In this work, activated biochar has been made by using corncobs. The biomass was first dried and minced into small pieces and pyrolyzed. Then, it was mixed with KOH and pyrolyzed for a second time. The final product was characterized by various techniques and its electroactivity as a cathode was determined. Physicochemical characterization revealed that the biochar had a hierarchical pore structure, moderate surface area of 92 m2 g−1, carbon phase with a relatively low sp2/sp3 ratio close to one, and a limited amount of N and S, but a high number of oxygen groups. The graphitization was not complete while the biochar had an ordered structure and contained significant O species. This biochar was used as an electrocatalyst for ORR and OER in Zn–air batteries where it demonstrated a satisfactory performance. More specifically, it reached an open-circuit voltage of about 1.4 V, which was stable over a period of several hours, with a short-circuit current density of 142 mA cm−2 and a maximum power density of 55 mW cm−2. Charge–discharge cycling of the battery was achieved between 1.2 and 2.1 V for a constant current of 10 mA. These data show that corncob biochar demonstrated good performance as an electrocatalyst in Zn–air batteries, despite its low specific surface and low sp2/sp3 ratio, owing to its rich oxygen sites, thus showing that electrocatalysis is a complex phenomenon and can be served by biochars of various origins.