Spherical Structure Research Articles

A unified Jacobi-Ritz-spectral BEM for vibro-acoustic behavior of spherical shell

In order to solve the vibration and acoustic characteristics of spherical shell in light fluid environment, based on Jacobi-Ritz-spectral BEM, a unified analysis formula for acoustic vibration of spherical shell under arbitrary boundary conditions is established. Based on the First-order shear deformation theory (FSDT) and domain decomposition method (DDM), the theoretical model of spherical shell structure is established. The improved Jacobi polynomial is innovatively used to construct the displacement tolerance function of the spherical shell. Based on the spectral Kirchhoff-Helmholtz integral formula, the theoretical model of the acoustic fluid outside the spherical shell is established. The special form of Jacobi polynomial Chebyshev polynomial is used to describe the excitation sound pressure on the spherical shell segment, so as to ensure that the generalized coordinates of the structure can be perfectly matched with the acoustic boundary element nodes. In addition, the integration along the meridian of the shell is used to control the movement of the fluid, which simplifies the surface integration. The CHIEF method is used to solve the problem of non-unique solution of acoustic variables of rotary structure. Compared with the published literature, numerical simulation results and experimental results, the proposed method has higher calculation accuracy. In addition, based on this method, the influence of boundary conditions, geometric dimensions and other factors on the acoustic and vibration characteristics of spherical shells is discussed, which accumulates data for analyzing the acoustic and vibration behavior of spherical shells.

In vitro characteristics of purified recombinant hepatitis C virus core protein

In our previous study, we established a method for purifying bacterially expressed HCV core 1–164 under non-denaturing conditions. In the present study, we elucidated the characteristics of the purified core. The purified HCV core exhibited a notable affinity for HCV RNA, with a Kd of 3 nM, as determined by a filter binding assay. Electron microscopy analysis revealed that the purified HCV core self-assembled with RNA into spherical structures approximately 50 nm in diameter. Additionally, we demonstrated the direct binding of the purified HCV core to the purified endoplasmic reticulum (ER). Moreover, lipid strip assays revealed specific binding of the purified HCV core to specific phospholipids, suggesting that the core plays a role in specific ER membrane domains. These studies reveal the biochemical characteristics of the HCV core that significantly advance our understanding of its role as a capsid protein in the viral lifecycle and pathogenesis.

Ultrasound‐Responsive Lipid Nanoparticles for Targeted Therapy and Controlled Drug Release in Non‐Small Cell Lung Cancer

AbstractMultifunctional drug delivery systems offer tremendous potential for improving antitumor efficacy, precise drug targeting, and controlled drug release in treating non‐small cell lung cancer (NSCLC). In this study, the study develops a novel tumor‐targeting ultrasound‐responsive lipid nanoparticle (TUSL) platform capable of responding to external stimulation, enabling precise drug delivery with controlled release at the tumor site while minimizing systemic exposure and side effects. The TUSL platform is designed to carry doxorubicin (DOX) and tetrandrine (TET), specifically for drug‐resistant NSCLC. The developed TUSL exhibits a nano sized spherical structure with a hydrodynamic size of 141.8 nm, accommodating anti‐cancer drugs with loading capacities of 3.8% and 6.2% for TET and DOX, respectively. TUSL is engineered to target the epidermal growth factor receptor (EGFR) while demonstrating an ultrasound‐triggered drug release profile. Through the generation of CO2 bubbles upon ultrasound stimulation, the TUSL enhances DOX and TET internalization into tumor cells. In tumor‐bearing mice, TUSL administration demonstrates a superior tumor accumulation with minimal off‐target toxicity. The combined treatment with DOX and TET within TUSL exhibits synergistic effects, effectively inhibiting the growth of drug‐resistant NSCLC tumors. These findings highlight the efficacy of the EGFR‐targeted TUSL formulation in overcoming drug resistance and enhancing therapeutic outcomes in NSCLC.

Antidiabetic, anti-inflammatory, antioxidant, and cytotoxicity potentials of green-synthesized zinc oxide nanoparticles using the aqueous extract of Helichrysum cymosum

The current research involved the synthesis of zinc oxide nanoparticles (ZnO-NPs) using an aqueous extract of Helichrysum cymosum shoots, and subsequent characterization via different analytical methods, such as UV–Vis spectroscopy, Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Transmission electron microscope (TEM), and zeta potential. The biological effects of the ZnO-NPs were then tested against C3A hepatocyte cells and L6 myocyte cell lines via series of analysis, including cytotoxicity, antioxidant, anti-inflammatory, and antidiabetic effect via enzymatic inhibition. The UV–Vis analysis showed a maximum absorption spectrum at 360, and the TEM analysis reveals a spherical and hexagonal structures, with an average dimension of 28.05–58.3 nm, and the XRD reveals a crystalline hexagonal structure. The zeta potential evaluation indicated that the ZnO-NPs are relatively stable at − 20 mV, and the FTIR analysis identified some important functional group associated with phenolics, carboxylic acid, and amides that are responsible for reducing and stabilizing the ZnO-NPs. The synthesized ZnO-NPs demonstrated cytotoxic effects on the cell lines at higher concentrations (125 µg/mL and 250 µg/mL), complicating the interpretation of the results of the inflammatory and antioxidant assays. However, there was a significant (p < 0.05) increase in the inhibitions of pancreatic lipase, alpha-glucosidase, and alpha-amylase, indicating beneficial antidiabetic effects.

Phenotypic and molecular characterization of Prototheca wickerhamii from a Brazilian case of human systemic protothecosis.

The genus Prototheca (alga) comprises a unique group of achlorophyllic saprotrophic and mammalian pathogen species. Despite its rare occurrence in humans and animals, protothecosis is considered an emerging clinical entity with relevance in immunocompromised patients. In this study, the characterization of spherical structures with endospores recovered from a blood culture in an HIV patient was investigated using phenotypic and molecular methodologies. On 2% Sabouraud dextrose agar, the isolate displayed morphological and biochemical characteristics found on isolates identified as Prototheca wickerhamii. To validate these analyses, molecular phylogeny of the internal transcript space (ITS) partial gene confirmed the identity of the isolate as P. wickerhamii. This is the first case of systemic human protothecosis in Brazil. The present case of human Prototheca and those reported in the medical literature highlight the need for novel methodologies to identify pathogenic algae in the clinical laboratory, improving in this way the diagnosis and treatment of this group of neglected pathogens.

Alkalized MQDs/Bi2S3 Porous Structure for Efficient Photocatalytic CO2 Reduction

AbstractFinding effective and specific catalytic materials for the transformation of carbon dioxide into fuel is indisputably a significant challenge. In this study, 3D porous sphere structure MXene quantum dot/Bi2S3 (MBS) composites were prepared using electrostatic self‐assemblage of protonated Bismuth sulphide nanoparticles (Bi2S3 NSs) with Ti3C2(OH)2 QDs (MQDs‐OH). The optimized MBS material demonstrates an excellent narrow band gap (Eg=1.24 V (vs. NHE)) and high selectivity and efficiency in catalyzing CH3OH, delivering impressive yields of up to 694.7 μmol/g. This study may lead to a new approach to the development of multidimensional photocatalysts for CH3OH production by adsorption of atmospheric CO2.

The Aerodynamic Assessment and Shot Point Position Accuracy of UAV Seismic Source

An unmanned aerial vehicle (UAV) seismic source, suitable for complex terrains due to its eco-friendly, cost-effective, and efficient nature, operates by hovering and releasing impact objects to generate seismic waves. The aerodynamic behavior of these impact objects is vital for shotpoint position accuracy and drag magnitude. Excessive drag will result in the loss of seismic source energy, whereas the deviations of the shotpoint position will disrupt the geometric structure of the observation system, significantly impacting the quality of seismic data acquisition. Through theoretical calculations, the influencing factors of air resistance and cross-wind deflection are analyzed. Air resistance increases with the increase in mass, cross-sectional area, speed, and drag coefficient. Increasing the mass and throwing height can increase the upper limit of the output, but after the air resistance and gravity are balanced, the output kinetic energy of the drone’s seismic source will no longer increase when the throwing height is increased. Using computational fluid dynamics simulations and field tests, this study examines the aerodynamics of four prevalent impact object designs. The results show that shuttle and spherical structures have the least drag during descent and are less influenced by crosswinds, thus being optimal for this application. Field measurement data are also presented for reference.

Optimization of Extraction Process, Structure Characterization, and Immunomodulatory Activity of Polysaccharides from Black Garlic

AbstractUltrasound assisted extraction (UAE) was used to extract polysaccharides from black garlic, and the extraction process for UAE of black garlic polysaccharides (BGPs) was optimized via RSM coupled with genetic algorithm. The optimal extraction process parameters were obtained as follows: extraction time of 30 min, liquid‐to‐solid ratio of 29 mL/g, extraction temperature of 51 ℃, and ultrasound power of 418 W, and the yield of BGPs was 10.17% ± 0.14%. Subsequently, the crude BGPs were further purified by DEAE‐52 cellulose and Sephadex G‐100 to obtain a homogeneous fraction (BGPs‐1‐SG with the molecular weight of 1.37 × 106 Da) that was comprised of mannose (Man), glucuronic acid (GlcA), rhamnose (Rha), glucose (Glc), and fucose (Fuc) with a molar ratio of 40.23:71.06:2.96:85.38:7.32. Congo red and circular dichroism spectroscopy indicate that BGPs‐1‐SG has a triple helix structure. Scanning electron microscope and atomic force microscope demonstrate that BGPs‐1‐SG showed irregular structures including sheet‐like, rod‐shaped, irregular spherical structures, and aggregated in aqueous solutions. Moreover, BGPs‐1‐SG could increase viability, phagocytic rate, and NO content of RAW264.7 cells. Furthermore, BGPs‐1‐SG could promote the secretion and mRNA expression levels of IL‐1β, IL‐6, and TNF‐α. The findings can provide an important reference for the development of functional foods.

Carbon-coated ZnS as a high-performance ORR/OER bifunctional cathode catalyst for zinc-air batteries

The commercial application of zinc-air batteries (ZABs) is hindered by the high cost and scarcity of precious metal catalysts. In this paper, we prepared high-performance ORR/OER bifunctional catalysts with a carbon-coated ZnS spherical structure (ZnS@C) through a hydrothermal method followed by a carbonization process. Characterized by their unique spherical coated pore structure, exhibit impressive electrocatalytic activity. Specifically, ZnS@C-2, produced by a secondary carbonization process demonstrates an ORR half-wave potential of 0.82 V (relative to RHE) and an OER overpotential of 377 mV at 10 mA cm−2. When employed in a ZAB, it achieves a maximum power density of 120.4 mW cm−2, a specific capacity of 836 mAh gZn−1, and maintains cycle stabilization for up to 165 h at 10 mA cm−2. The research results demonstrate that the unique carbon-coated internal porous structure not only significantly enhances the stability of the catalyst but also increases the number of active sites, thereby providing more abundant activation energy for the catalytic reaction and facilitating its efficient progress. This underscores the catalyst's excellent ORR and OER properties, suggesting promising practical application potential.

Green synthesis of silver nanoparticle by Hyoscyamus muticus L. extract and study of its effect on tomato infected with Meloidogyne javanica

In this study, the aqueous leaf extract of Hyoscyamus muticus L Plant leaf was prepared using three methods: maceration (MAC), microwave-assisted extraction (MAE), and ultrasonic-assisted extraction (UAE). Then, the extracts were used to synthesize silver nanoparticles (Ag NPs) in an environmentally friendly approach. The characterization of the synthesized Ag NPs was carried out by various techniques. The XRD results confirmed the successful synthesis of nano-sized Ag crystals with spherical structure. The SEM images showed the formation of Ag NPs, which were smaller than 75 nm. The UV-Vis studies showed an obvious absorption peak for Ag NPs between 400-500 nm, with a clear peak around 450 nm for all samples. The elemental analysis using the EDS technique confirmed the presence of silver in the synthesized Ag NPs. Furthermore, the effect of different concentrations of Ag NPs was investigated on hatching and second-stage juvenile (J2s) mortality of Meloidogyne javanica, under controlled conditions. The results showed that increasing concentrations of Ag NPs led to higher percentages of inhibition of egg hatching and J2s mortality. Additionally, the Ag NPs synthesized by ultrasonic-assisted extraction with lower lethal concentration were found to be more toxic to M. javanica than the extract prepared by soaking. According to the results, Ag NPs showed a stronger inhibitory effect on M. javanica egg hatching and J2s mortality compared to the total extracts and chemically synthesized Ag NPs. Also, the lowest LC50 was observed for the Ag NPs synthesized using the plant extract as: UAE > MAE (180 w) > MAE (90 w) > MAC methods. The highest inhibition of egg hatch occurred at 0.5 % v/v of Ag NPs after 72 hours and remained consistent after 120 hours.

Multifaceted evaluation of pyrazole derivative (T4)-chitosan (CS) nanoparticles: Morphology, drug release, and anti-tumor efficacy in a rat model.

The development of targeted nanotherapeutics has emerged as a pivotal advancement in cancer treatment, aiming to enhance the efficacy and specificity of drug delivery while minimizing systemic toxicity. Due to their biocompatibility and modifiable surface properties, Chitosan-based nanoparticles have shown considerable promise in encapsulating and delivering therapeutic agents directly to tumor sites. This study investigates the potential of 1,5-diary pyrazole derivative (T4)-loaded chitosan (CS) nanoparticles as a novel anticancer agent, evaluating their physical characteristics, in vivo biodistribution, and therapeutic efficacy against cancerous cells. SEM morphological analysis confirmed chitosan-based nanoparticles' smooth, spherical structure, with aggregation patterns typical of high surface energy nanoparticle synthesis. UV-visible spectroscopy and XRD analysis validated the successful incorporation of T4, showing characteristic absorption peaks and indicating a reduction in crystallinity desirable for enhanced drug release. In vivo imaging demonstrated the rapid systemic distribution of T4-CS nanoparticles, essential for delivering therapeutic agents effectively. The cytotoxic potential of T4-CS nanoparticles was significantly higher against cancer cells compared to controls, confirmed by MTT and scratch assays, indicating enhanced anti-cancer activity and potential inhibition of cancer metastasis. Furthermore, histological and gene expression analyses supported the anti-tumor and pro-apoptotic capabilities of T4-CS nanoparticles, showing reduced proliferation markers and inflammatory pathways. Behavioral assessments in rats highlighted the neuroprotective effects of T4-CS nanoparticles against 7,12-dimethyl benzanthracene (DMBA) induced neurotoxicity, suggesting their utility as both anticancer and neuroprotective agents. This multifaceted evaluation underscores the versatility and therapeutic potential of T4-CS nanoparticles, warranting further investigation into their mechanistic effects and clinical applications.

Design, Optimization, and Autonomous Construction of Martian Infrastructure including Slabs Using In-situ CO2-Based Polyethylene

A crucial development in 21st-century space exploration is the establishment of human settlements on Mars. In recent years, Mars exploration rovers have been deployed, and studies investigating human journeys to Mars have been conducted, with the objective of a human-crewed mission to Mars before 2050. This study presents an innovative approach to designing and optimizing Martian habitats by using in-situ CO2-based polyethylene (PE) as a construction material for Martian buildings and greenhouses. It seeks to develop sustainable and resilient habitats on Mars, leveraging local resources to address the environmental challenges specific to the Martian environment. The research targets several key areas: realistic construction techniques, effective utilization of in-situ materials, and building resilience under the harsh Martian conditions. These conditions include radiation, micrometeoroid impacts, low atmospheric pressure, low gravity, wind storms, temperature extremes, Paschen discharge, and marsquakes. Finite element analysis (FEA) of several pressurized spherical structures is used to design and optimize for minimum material usage, inspired by soap bubbles that naturally stick together with separating walls. The proposed habitat design features a central spherical structure surrounded by nine smaller spheres, optimized for material efficiency. It is demonstrated that utilizing two layers of 0.1 m thick PE and a 0.5 m thick CO2 layer in between them offers significant protection against Martian environmental loads such as radiation shielding and thermal insulation. It facilitates light transmission into the building. This study offers a realistic structural system for buildings and greenhouses that can be constructed using in-situ materials and is suitable for an optimal 539-day stay on Mars. The proposed autonomous robotic arm technology can perform all necessary tasks, from producing PE to automatically assembling the Mars Spherical Building (MSB), including in-place slab printing.

Reduced Graphene Oxide/Silica Based Electrode Material: Synthesis and Characterization

&lt;span lang="EN-US"&gt;Developing a Reduced Graphene Oxide (rGO) synthesis method based on rice husk as a composite electrode material with silica has garnered particular attention for designing high-quality electrode materials. This research successfully synthesized rGO-Si material from rice husk-derived activated carbon through a one-step thermal reduction process at 200 °C. This method offers a simple, efficient, cost-effective, and environmentally friendly synthesis approach. The resulting samples' morphology, surface composition, crystal structure, surface area, and pore diameter size were characterized using FE-SEM, EDX, XRD, and SAA-BET. EDX characterization results confirmed the predominance of carbon content in the samples. At the same time, the natural emergence of Si without external addition due to thermal reduction at 200 °C was an intriguing initial finding. The spherical crystal structure of silica between the wrinkled rGO layers was confirmed through FE-SEM and XRD analysis. The synergistic effect between Si and rGO significantly increased the sample's surface area, with a value of 34.17 m&lt;sup&gt;2&lt;/sup&gt;/g for the rGO sample before thermal reduction, which increased to 121.24 m&lt;sup&gt;2&lt;/sup&gt;/g after the thermal reduction process at 200 °C. This process also positively impacted the reduction in pore size of rGO-Si, with a value decreasing from 9.33 nm before thermal reduction to 4.89 nm after the thermal reduction process. The results of this study demonstrate that rGO-Si synthesized from rice husk-derived activated carbon holds great potential as a high-performance electrode material, combining the advantages of thermal reduction, natural Si content, and increased surface area for diverse applications.&lt;/span&gt;

Acoustically tunable intra-droplet assembly of organoids towards high-throughput tumor model construction

Three-dimensional cell organoids and spheroids are increasingly recognized as physiologically relevant models for ex vivo research and therapeutic screening. However, there remains a need for a cost-effective and convenient platform to fabricate these models with well-defined architectures for downstream applications. Here, this work proposes micro models constructing in the droplet platform, by acoustic forces, that can obtain 3D cellular organoids with tunable structures at high yield. By modulating signals applied to acoustic devices, a periodic potential array with adjustable structures is formed, enabling uniform trapping and patterning of droplets. Simultaneously, the localized potential is also formed inside droplets, resulting in the active assembly of cells. Then, hydrogel droplets containing the constructed models are crosslinked, providing ECM to mimic the 3D scaffolds. In experiment, MCF-7 cells are assembled into spherical, linear and cross structures. This method can generate thousands of tumor spheroids in one minute. The long-term culturing results indicate an enhanced efficiency in forming mature tumor models compared with control groups. This biomanufacturing technology has the advantages of being high-throughput, low-cost, and tunable, making it a robust tool for droplet-based applications such as tissue engineering, drug screening, and disease modeling etc.

Core mechanism for the stability preparation of lithium slag-based SOD zeolite: Evolution of trans-crystallization nucleation/growth kinetics of crystals

SOD nano-zeolite has been widely applied in the separation of small gas molecules since these advantages comprise a high-density framework and favorable acid/alkali resistance. Moreover, the bottleneck for the lithium sector can be ameliorated by industrializing the manufacture of SOD zeolite (SLS) from the hazardous waste lithium slag (LS). However, the stability in industrial production is restricted owing to the ambiguous nature of the lattice nucleation/transformation mechanism. Herein, it was discovered that the highest relative crystallinity (98.8 %) of SLS with a layered spherical structure could be achieved under the crystallization condition of heating at 95 °C for 8 h. The nucleation and growth mechanisms of SLS crystals demonstrated a three-dimensional crystal growth pattern characterized by sporadic and transient nucleation, which is essentially consistent with that of crystallization kinetics. Specifically, the activation energies of the induction, transformation and crystallization phases were 41.33, 27.99 and 46.99 kJ·mol−1, respectively, implying that the directional induction of the transition phase is crucial for obtaining SLS with high crystallinity. Two nucleation processes can also be observed in the transformation stage, involving homogeneous nucleation and polymorphic transformation. Our study explored the crystallization and assembly mechanism of SLS crystals, providing a well-defined concept for the regulation of stability preparation.

Efficient recovery of Pd(II) from nuclear wastewater using a functionalized covalent organic frameworks with uniform spherical structure: Size control, performance and mechanism insight

The efficient recovery of palladium from the spent nuclear fuel was of great significance to the sustainable development of nuclear energy. Herein, the uniform spherical COFs were constructed by a facile approach at room temperature, which were further surface functionalized by a thiol-ene “click” reaction to recover Pd(II). Microscopic and spectroscopic studies manifested that the formation mechanism and size of spherical COFs were greatly affected by the amount of catalyst and solvent type. The TAPB-BPTA-DTT and TAPB-BPTA-S-β-CD exhibited high Pd(II) recovery efficiency due to the introduction of sulfhydryl groups, and the maximum adsorption capacities were 489.3 and 234.3 mg/g, respectively. Meanwhile, the water environmental condition played an important role in the separation process, and the classical adsorption models demonstrated that monolayer chemisorption was the dominant removal mechanism. Mechanism analysis showed that the excellent adsorption performance was mainly attributed to the electrostatic interaction, physical absorption and chelation of N, O, and S groups with Pd(II). Thus, it is expected that this work could provide more insight into COFs materials, thereby promoting palladium removal advancements in the spent nuclear fuel.

Sea urchin-like Fe3O4 hollow microspheres/fatty amines composites phase change materials for highly efficient light-to-thermal conversion and heat storage

Pure phase change materials (PCMs) have limited photothermal conversion capabilities. To improve the photothermal conversion capability of PCMs, we developed composite phase change materials (FHS@PCMs) of sea urchin-like Fe3O4 hollow spheres (FHS) loaded with fatty amines (hexadecylamine (HDA) and octadecylamine (ODA)). The material composition and the surface nano-raised structure of FHS enable FHS@PCMs to exhibit excellent light absorption (up to 90 %, without any additional modification) and thermal conductivity. Moreover, the internal hollow spherical structure would prevent the leakage of PCM during the phase change process. Interestingly, FHS and FHS@PCMs exhibit inherent superhydrophobic properties with a water contact angle greater than 150°, thus endowing them with self-cleaning properties. FHS possesses strong magnetic properties that aid in material collection. Furthermore, the prepared FHS@PCMs exhibited exceptional thermal properties. The latent heat of FHS@HDA and FHS@ODA was 139.21 J∙g−1 and 140.13 J∙g−1, respectively. Additionally, FHS@PCMs maintained their excellent thermal properties even after 50 and 100 thermal cycles. Under one solar radiation, FHS@PCMs show a photothermal conversion efficiency of 89.63 % and 88.02 %, respectively. Taking of these advantages, the as-prepared composite phase change material may have significant potential in the fields of solar energy conversion and storage.

The oxidized hyaluronic acid hydrogels containing paeoniflorin microspheres regulates the polarization of M1/M2 macrophages to promote wound healing

Controlling excessive inflammation of acute wound is an effective means to shorten the healing time. Therefore, targeted control of the inflammatory response of the wound is a promising therapeutic strategy. In this study, paeoniflorin (Pae) was encapsulated in microspheres and combined with oxidized hyaluronic acid hydrogels to prepare the hydrogel loaded with Pae microspheres (Pae-MPs@OHA) to promote the healing of acute wounds in rats. The results demonstrated that the particle size of the Pae-MPs was 6.84 ± 0.51 μm, and the positive charge was 26.87 ± 1.51 mV. The uniform spherical structure of the Pae-MPs was observed by TEM. The Pae-MPs@OHA can maintain colloidal state in the range of 0.1–3.16 Hz. FTIR suggested that Pae could be effectively wrapped in MPs, and SEM indicated that the Pae-MPs@OHA had a uniform network pore structure. The Pae-MPs@OHA can realize the sustained release of Pae for 96 h. Biocompatibility experiments showed that the Pae-MPs@OHA hydrogels were safe and available. The Pae-MPs@OHA hydrogels can accelerate wound healing in rats. HE and masson staining suggested that the Pae-MPs@OHA could reduce inflammatory cell infiltration, promote re-epithelialization and collagen formation. The Pae-MPs@OHA could decrease the number of M1 and increase the number of M2 in macrophages, thus regulating the release of inflammatory factor TNF-α and IL-1β. The results of molecular docking and western blot results also confirmed that the Pae-MPs@OHA could reduce the expression of NF-κB, pNF-κB, NLRP3, ASC and pro-caspase-1. These findings suggest that the Pae-MPs@OHA has great potential for application in the treatment of inflammatory wound.

Hexagonal boron nitride fibers as ideal catalytic support to experimentally measure the distinct activity of Pt nanoparticles in CO2 hydrogenation

Catalytic studies aim to design new catalysts to eliminate unwanted by-products and obtain 100 % selectivity for the preferred target product without losing activity. For this purpose, understanding the role of each component building up the catalyst is essential. However, determining the intrinsic catalytic activity of pure metals, especially precious metals in the CO2 hydrogenation reaction under ambient conditions is complex. This is because the catalyst supports used thus far always influence the catalytic process either directly or indirectly due to interface formation that modifies the electronic and morphological structure of the metals. Even SiO2, regarded as inert shows some activity owing to the hydroxyl groups on its surface. In this work, we propose chemically inert and defect-free hexagonal boron-nitride fibers (BNF) synthesized via a co-precipitation method with wide band gap and robust covalent bonds as an uncommon reference catalyst support to evaluate the catalytic activity of size-controlled Pt nanoparticles (4.7 ± 0.6 nm) in the hydrogenation of CO2. The fibers alone show no catalytic activity; however, Pt/BNF exhibited low but notable activity of 377 nmol/g at 400 °C and the catalyst can achieve nearly 100 % CO selectivity. X-ray photoelectron spectroscopy, transmission electron microscopy, and diffuse reflectance infrared Fourier transform spectroscopy measurements were used to indicate that hexagonal boron-nitride affects neither the metal nanoparticles nor the reaction itself; the measured catalytic activity stems from the activity of Pt deposites without the effect of the support, as they were alone. CO vibration spectroscopy studies suggest that due to the lack of substrate-metal interaction, Pt nanoparticles adopt an ideal spherical structure, resulting in several low coordination sites capable of CO2 conversion. Thus, BNF is proposed in the present article to be used as a reference catalyst support material. It can be efficiently used in investigations involving the proposed metal and reaction or under varying conditions with different metal nanoparticles and reaction systems.

Spherical Ru/FeOx composite as a bifunctional electrocatalyst for overall water splitting in neutral media

Electrochemical water splitting stands out as a promising technology for H2 production, due to its simplicity and high energy conversion efficiency. Therefore, it is a key issue to develop and design efficient catalysts for overall water splitting (OWS), especially in neutral media. Herein, the present study presents a stable bifunctional electrocatalyst, namely a spherical structure consisting of ruthenium and iron oxide composite supported on iron foam (Ru/FeOx), which was prepared using a simple two-step process. In 1.0M PBS, the optimized Ru/FeOx-300 demonstrates low overpotentials of 30 and 212mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at 10mAcm-2, respectively. More impressively, Ru/FeOx-300 requires only 1.505V to achieve a current density of 10mAcm-2 and exhibits superior electrochemical stability for 24h in a two-electrode neutral electrolyzer. The outstanding catalytic performance and stability of Ru/FeOx-300 nanospheres for water splitting are attributed to the binder-free integrated structure, the enhanced charge transfer facilitated and the synergistic effect between Ru and FeOx. This study offers a novel approach to the development of high-efficiency electrocatalysts for overall water splitting in neutral media.