Agglomeration Of Nanoparticles Research Articles

Effect of Heat Treatment on Structure of Carbon Shell-Encapsulated Pt Nanoparticles for Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) have attracted much attention as highly efficient, eco-friendly energy conversion devices. However, carbon-supported Pt (Pt/C) catalysts for PEMFCs still have several problems, such as low long-term stability, to be widely commercialized in fuel cell applications. To address the stability issues of Pt/C such as the dissolution, detachment, and agglomeration of Pt nanoparticles under harsh operating conditions, we design an interesting fabrication process to produce a highly active and durable Pt catalyst by introducing a robust carbon shell on the Pt surface. Furthermore, this approach provides insights into how to regulate the carbon shell layer for fuel cell applications. Through the application of an appropriate amount of H2 gas during heat treatment, the carbon shell pores, which are integral to the structure, can be systematically modulated to facilitate oxygen adsorption for the oxygen reduction reaction. Simultaneously, the carbon shell functions as a protective barrier, preventing catalyst degradation. In this regard, we investigate an in-depth analysis of the effects of critical parameters including H2 content and the flow rate of H2/N2 mixed gas during heat treatment to prepare better catalysts.

Kinetic evaluation of the uranyl peroxide synthetic route on morphology

Abstract An important challenge in utilizing particle morphology in nuclear forensic or fuel fabrication applications is understanding why differences in morphologies are observed following varying processing conditions. This is often due to competition and interplay between thermodynamic and kinetic influences. To that end, some of the kinetic influences in the uranyl peroxide precipitation reaction were evaluated and compared to thermodynamic influences studied previously. Metastudtite (UO2O2·2H2O) was synthesized from solutions of uranyl nitrate or chloride, and the reaction time was varied from 100 s to 230 min enabling an evaluation of kinetic and thermodynamic influences. The metastudtite was then calcined to U3O8, and all materials were analyzed by powder X-ray diffraction (p-XRD) and scanning electron microscopy (SEM). Analysis by p-XRD confirmed the sample purity of metastudtite and U3O8. SEM images were analyzed using the Morphological Analysis for Materials (MAMA) software to measure the size and shape of the nanoparticles for a statistical comparison between materials. Metastudtite produced at shorter reaction times exhibited a kinetically controlled shape by forming smaller and rounder particles than metastudtite produced at longer reaction times. Metastudtite produced at the longer reaction times exhibited differences between the uranyl nitrate and uranyl chloride routes with the nitrate exhibiting a more angular and faceted morphology than the chloride. Overall, the control of the supersaturation ratio (S) played a significant role in determining the morphology of the metastudtite. Morphological differences between the U3O8 confirmed the role of nanoparticle agglomeration in forming larger sintered particles. The results help demonstrate the importance of understanding particle formation mechanisms in the long-term development of morphology in nuclear forensics or in developing advanced fuels with specific characteristics.

The effect of doping sulphhydryl-functionalised silica with different diameters on the electro-optical properties of PDLC

ABSTRACT In this study, we synthesised two kinds of spherical SiO2-SH particles with uniform and non-uniform morphologies, and investigated their effects on the electro-optical properties of PDLC. Compared with uniform SiO2-SH nanoparticles, we found that the samples doped with non-uniform SiO2-SH regulate the electro-optical properties of PDLC better. The electro-optical properties test results demonstrated that doping a small amount of SiO2-SH with different sizes significantly reduced the driving voltage of PDLC and maintained a high contrast ratio. SEM results indicated that the size of the polymer meshes was broadened with increasing SiO2-SH doping. This phenomenon can be attributed to the larger specific surface area and higher concentration of sulphhydryl groups in SiO2-SH particles of different sizes. These characteristics enable SiO2-SH to better react with acrylate monomers, thereby improving modulation effects on the electro-optical properties of PDLC. However, when the doping amount exceeded a certain value, the driving voltage of PDLC began to rise, and its electro-optical properties deteriorated because of the agglomeration of nanoparticles at higher doping levels. This study demonstrated that doping SiO2-SH particles of different sizes can optimise the properties of PDLC, which provided new ideas and directions for doping PDLC with nanomaterials.

Sustainable calcium oxide nanoparticles based on agroindustry waste for potential endodontics applications

Development of sustainable proposals in various areas has been crucial nowadays. Thus, this research evaluated a sustainable synthesis of calcium oxide nanoparticles (CaO NPs), using an agroindustry waste from eggshells to promote dentistry tissue regeneration with antimicrobial activity. Then, eggshells were loaded to heat treatment with two different temperatures (700 °C and 900 °C) for three times (7, 15 and 24 h). These CaO NPs were characterized using spectroscopies (UV Vis, FTIR, XRD) and morphological (ZP, SEM, TEM). Additionally, antimicrobial activity against Escherichia coli and Candida albicans, cell viability, protein adsorption and alkaline phosphatase activity were evaluated. The results showed that CaO NPs were produced in both temperatures, but in the slow heating (at 700 °C), Ca(OH)2 was still presented. Moreover, morphological analysis showed charges close to zero, indicating high agglomeration of nanoparticles proved by SEM images. The CaO NPs’ size were in the range of 10 and 25 nm at 900 °C and showing high clustering and porosity at 700 °C by TEM analysis, and the band gap, 2.82–5.77 eV. Additionally, XRD showed nanoparticles of CaO and Ca(OH)2 in both temperatures, although in the case of high heating, the presence of more CaO was perceived. The cell viability was great for biological proposals, mainly in the sample performed at high temperature (over 90 %). Furthermore, the antimicrobial activity showed incredible results against both microbials with low calcium nanoparticles tested (40 μg). Thus, this research demonstrated a sustainable way to reusability agroindustry waste for dentistry applications.

Selective amination of furfuryl alcohol to furfurylamine over nickel catalysts promoted by alumina encapsulation

Direct amination of bio-based furfuryl alcohol over metal catalysts provides an alternative route to produce furfurylamine without consuming expensive reducing reagents. The harsh and reductive condition of furfuryl alcohol amination, however, requires high durability and excellent resistance to side furan-ring hydrogenation for efficient catalysts, which is still substantially challenging to non-noble metals. We show here that alumina-encapsulated Ni catalysts prepared via a sol–gel method exhibited an outstanding and stable performance in selective amination of furfuryl alcohol to furfurylamine under mild NH3 and H2 partial pressures. Structural characterization unveiled that the alumina framework with appropriate mesopores effectively restrained the agglomeration of Ni nanoparticles and the side furan-ring hydrogenation. A volcano-type dependance of the intrinsic activity of Ni nanoparticles on their sizes was established with the maximum attained at about 5 nm, which correlated well with the redox ability of surface Ni sites. Kinetic assessments further indicated the kinetic relevance of furfural formation from furfuryl alcohol dehydrogenation, evidenced by quasi-zero and negative reaction orders on NH3 and H2 pressures, respectively. Combined with infrared spectroscopy, furfuryl alcohol was identified as the predominant adsorbed species with a nearly saturated coverage under reaction condition, consistent with the high susceptibility of furan-ring hydrogenations to H2 pressure. As a consequence, a slight amount of inert Ag (0.05 wt%) was introduced onto the alumina-encapsulated Ni catalysts to weaken the adsorption of furfuryl alcohol and its derivatives, which suppressed the side over-hydrogenation reactions to an extremely low level without sacrificing catalytic activity significantly.

A novel aloe vera mediated Bismuth–Magnesium–Copper nanocomposite for radiation shielding applications

In the current study, Bismuth-Magnesium-Copper nanocomposites (BMC NCs) are synthesized using versatile solution combustion synthesis using Alovera extract as a reducing agent. As obtained BMC NCs are characterized using standard techniques. Bragg’s reflections confirmed the formation of multi-phase BMC NCs with crystal sizes 18.11 nm and 21.12 nm. The surface morphology of BMC NCs confirmed the agglomeration of spherical-shaped nanoparticles. EDAX spectrum analyzed the presence of Bi, Mg, and Cu. The direct energy gap is found to be 3.08 eV. X-ray/gamma radiation shielding properties are then evaluated using a NaI(Tl) detector coupled with MCA. Shielding parameters are slightly higher than lead. Neutron shielding parameters are compared with conventional shielding materials. Scattering length is found to be 8.8 fm, and neutron absorption cross-section and neutron attenuation parameters of BMC NCs are found to be efficient when compared with lead, concrete, and steel. Bremsstrahlung radiation shielding parameters are computed at 1.511 MeV. Bremsstrahlung efficiency is comparable to lead, bremsstrahlung dose rate and specific bremsstrahlung constant are found to be more in comparison with lead. Thus, BMC NCs are highly efficient in shielding X/gamma ray and neutron radiations.

Universality of hydroxyl radical generation in irradiated nanoenhancer suspensions: Vital role of concentration

Concentration plays an essential role in generating hydroxyl radicals in irradiated nanoenhancer suspensions. In this paper, we used coumarin-3-carboxylic acid as a hydroxyl radical-specific probe to investigate the hydroxyl radical production of different concentration nanodiamonds (NDs) and CeO2 NPs in phosphate-buffered saline under x-ray irradiation. NDs significantly enhanced hydroxyl radical production, and the maximum enhancement of hydroxyl radical production was observed at a concentration of 10 µg/ml, with an enhanced factor of 1.398 ± 0.262. CeO2 NPs can increase and scavenge hydroxyl radicals at different concentration ranges, with the lowest and highest enhanced factors of 0.623 ± 0.069 and 1.738 ± 0.264, respectively. We tested the hydrodynamic diameter at various concentrations to explore the concentration effect further. We found that with increasing concentration, there might be factors, such as hydroxyl radical recombination and nanoparticle agglomeration, that lead to changes in the enhancement factor. Based on the data from previous and present studies, the experimental results indicate that the concentration factor is essential for hydroxyl radical generation in nanoenhancer suspensions under ionizing radiation. We also provide possible mechanisms for enhancing hydroxyl radical production by nanoenhancers in water under ionizing radiation and the decrease in enhancement factor at high concentrations of nanoenhancers.

Long-term, rapid and stable acetone gas sensing performance of porous Rgo/flower-shaped ZnO nanocomposites with a hydrothermal synthesis method

It is prominent and imperative to synthesize gas-sensitive materials using energy-efficient and environmentally friendly methods to enhance their properties. The current paper employs hydrothermal method porous reduced graphene oxide (P-rGO) and zinc oxide (ZnO) with flower-like structure complexes (PGZ) to detect the acetone gas. The gas sensitivity of the PGZ sensor demonstrate a response of 30.38 for 50 ppm acetone, accompanied by a rapid response recovery time of 5 s/7 s at operating temperature of 240 °C. Moreover, the remarkable long-term stability (<15 % fluctuation over 9 cyclic response cycles and 7 weeks of intermittent testing) of the PGZ gas sensor ensures its suitability for practical applications. The P-rGO enlarges the specific surface area of the material, which is conducive to accelerating the electron transfer in the reaction as well as the adsorption and desorption of the target gas, resulting in a rapid response recovery time. The porous structure can also effectively inhibit the agglomeration and growth of ZnO nanoparticles, thus improving long-term stability. Consequently, our study provides a new strategy for the application of 2D materials in gas sensing.

Cobalt/nitrogen doped hollow carbon sphere-bamboo like carbon nanotube for highly efficient oxygen reduction reaction

The exploration of non-Pt catalysts with high electrocatalytic activity and durability is especially important for cathodic oxygen reduction reaction (ORR) in fuel cell. Here, cobalt and nitrogen doped hollow carbon sphere-bamboo like carbon nanotube (Co/NHCS-BCNT) is prepared by using SiO2 sphere as sacrificial template. Co nanoparticles are confined in the cavity and top end of the in-situ formed BCNT, which can not only avoid the agglomeration of Co nanoparticles but also inhibit corrosion in caustic electrolyte. The synergistic effect between NHCS and well-dispersed Co particles makes Co/NHCS-BCNT have superior catalytic activity toward ORR. The electrochemical surface area (ECSA) of Co/NHCS-BCNT is 222 cm2, which is higher than those of NHCS (164 cm2) and HCS (135 cm2). The onset potential and half-wave potential of Co/NHCS-BCNT are 0.941V and 0.814V, respectively, which are close to commercial Pt/C (0.949V, 0.807V). The Tafel slope of Co/NHCS-BCNT (63.8mV dec-1) is lower than that of Pt/C (71.7mV dec-1). In addition, Co/NHCS-BCNT shows excellent durability and fuel selectivity.

A novel method for multiple cardiovascular disease biomarker detection using a SERF-based microfluidic platform

As cardiovascular diseases (CVDs) are the leading cause of death worldwide, it is of great importance to realize a rapid and sensitive diagnosis. Multiple CVD biomarker detection, which holds higher accuracy and speed of early CVD diagnosis, is becoming a promising alternative to single biomarker analysis. Cardiac troponin I (cTnI), C-reactive protein (CRP), brain-type natriuretic peptide (BNP), and heart fatty acid binding protein (H-FABP) are four significant diagnostic biomarkers for CVDs. Among the several methods for biomarker detection, such as optical, magnetic, mechanical, and electrical methods, the magnetic method stands out because of its stability, low toxicity, noninvasive detection, facile manipulation with an external magnetic field, and immunity to the interference of background light. At present, the lack of multiplexing capability, the imprecision of magnetic signal localization, and the agglomeration and non-specific adsorption of magnetic nanoparticles all limit the clinical application of magnetic detection. This paper presented a novel method for multiple CVD biomarker detection using a spin exchange relaxation-free (SERF)-based microfluidic platform. One or more SERF atomic magnetometers were used to scan the remanent field of magnetic labels to detect four CVD biomarkers in 70min, with a detection limit of 1.88pg/mL (cTnI), 1.58pg/mL (CRP), 1.45pg/mL (BNP), and 1.71pg/mL (H-FABP). The results showed two-dimensional magnetic fields with a resolution of submillimeter level and a sensitivity of pT level. The measurement technique provides a new magnetic methodology for applications in clinical diagnosis.

Sulfur dioxide-resistant platinum-based intermetallic nanocatalysts encaged by porous nitrogen-doped carbon for oxygen reduction reaction

SO2, one of the considerable air pollutants, exhibits a stronger binding affinity with Pt when compared to O2, thereby inducing irreversible degradation of the Oxygen Reduction Reaction (ORR) catalyzed by Pt-based catalysts. Despite this detrimental phenomenon, scarce investigations have delved into the realm of contaminant-tolerant catalysts, and so far, no effective SO2-tolerant catalysts have been proposed. To meet this challenge, we designed and synthesized a core–shell structure catalyst equipped with a dual protection mechanism. This was achieved through the in-situ polymerization of aniline monomers, concomitantly reducing Pt2+. The resulting shell effectively hinders the transmission of SO2 to the active sites of Pt, while permitting the unimpeded transmission of O2. Simultaneously, the intermetallic core inhibits the adsorption of SO2. Therefore, this catalyst exhibits exemplary ORR activity coupled with exceptional resistance to SO2 resistance. In particular, the PtFe@FeNC/C-10 catalyst, optimized in terms of the quantity of added aniline, demonstrates a mass activity 1.84 times greater and a specific activity 4.03 times higher than that of commercial Pt/C catalysts. Following exposure to SO2-induced poisoning, the E1/2 value of the PtFe@FeNC/C-10 catalyst undergoes a decrease of only 51.7 mV, lower than that observed for the commercial Pt/C catalyst (92.0 mV). Moreover, the results of an accelerated durability test affirm the superior stability of PtFe@FeNC/C-10 in comparison to commercial Pt/C. This stability advantage is attributed to the protective carbon shell, which effectively prevents the detachment and agglomeration of Pt nanoparticles.

Magnetic zinc oxide/silica microbeads for the photocatalytic degradation of azo dyes

Photocatalysis is a promising technique for the complete degradation of azo dyes that are present in wastewater. In this work, a new photocatalyst in the form of ZnO/Fe3O4/SiO2 hybrid microbeads was fabricated for the photocatalytic degradation of methylene blue. The microbeads were synthesised through self-assembly and subsequent agglomeration of nanoparticles within an aqueous phase of a water-in-oil emulsion template. Photocatalytic degradation experiments were conducted through exposure of a methylene blue solution to UV light. The hybrid microbeads performed better than ZnO powder at the same initial dye and ZnO concentration because of higher adsorption and degradation. The initial concentration of dye solution and catalyst dosage have a significant impact on the degradation. Higher degradation is seen with lower initial dye concentration and higher catalyst dosage. The presence of magnetic nanoparticles within the beads allows for their full recovery and reuse for degradation experiments. Complete degradation of dye was achieved using the new ZnO/Fe3O4/SiO2 microbeads.

Synthesis of WL.nZVI/ GAC adsorbent green for chromium removal from aqueous solutions: (Characterization, kinetics, isotherms, and thermodynamics)

This paper aims to synthesize zero-valent iron green nanoparticles to remove chromium from aqueous solutions. A granular activated carbon base was used to solve the problem of nanoparticle agglomeration. This study produced zero-valent iron nanoparticles using walnut leaf extract and immobilization on granular activated carbon (WL.nZVI/ GAC). Then, the specifications of the nanocomposite were studied using FE-SEM, EDX, BET, FTIR, and XRD analysis. This study investigated the parameters affecting adsorption, such as pH, adsorbent dose, contact time, pollutant concentration, and temperature. The WL.nZVI/ GAC nanocomposite specifications showed that the nanoparticles are spherical, and the diameter of the iron nanoparticles immobilized on activated carbon was determined in the range of 16.77 to 27.72 nm. XRD results also indicated that the Wl.nZVI/ GAC adsorbent was amorphous. According to EDX analysis, the loaded iron content in WL.nZVI/ GAC was about 1.86 %. pHPZC for WL.nZVI/ GAC nanocomposites was determined in the range of 6.1; In other words, at pH less than 6.1, the adsorbent’s surface charge is positive and can absorb the chromium existing in solution, which is in the form of chromate, well. The results of adsorption process optimization showed that the adsorption of Cr(VI) is optimal at pH = 4, contact time of 780 min, concentration of 80 ppm, and temperature of 298 K. Experimental studies showed that the chromium removal by adsorbent is strongly dependent on pH. The adsorption kinetics of chromium by WL.nZVI/ GAC adsorbent follow the Pseudo-second-order, and the adsorption isotherm follows the Langmuir model. The adsorption of Cr(VI) ions on the Wl.nZVI/ GAC adsorbent is a spontaneous and exothermic process.

Effect of surface engineering of nanofillers using plasma-treated water for carbon dioxide capture in mixed matrix membranes: Experimental and molecular dynamics

This work introduces an innovative approach to enhance carbon dioxide (CO2) capture performance in mixed-matrix membranes (MMMs) by incorporating plasma-treated ceria (CeO2) nanoparticles into a polyurethane (PU)-based membrane. Functionalization of CeO2 by means of plasma aimed at improving interfacial interactions with both polymer matrix and CO2 gas molecules, with consequent enhancement of CeO2 nanoparticles dispersion within the matrix and improvement of gas separation performance. Based on the results of gas separation tests, the PU membrane containing 5 wt% plasma-treated CeO2 exhibited a CO2 permeability of 51.2 barrer and a CO2/N2 ideal selectivity of approximately 76.5, demonstrating a 26.1% increase in CO2/N2 ideal selectivity compared to the pristine PU membrane. However, a further increase in filler content to 10 wt% led to nanoparticle agglomeration, resulting in a decrease in selectivity due to the formation of non-selective pathways through the membrane. Molecular dynamics (MD) simulations corroborated these experimental findings, providing additional insights into the interaction mechanisms between the polymer matrix and the functionalized nanoparticles.

Effect of three-dimensional to one-dimensional orientation of cellulose nanofiber sizing agents on carbon fibers under magnetic and electric fields on composite material properties

Nanoparticle-containing sizing agents are essential for the overall performance of high-quality carbon fiber (CF) composites. However, the uneven dispersion of nanoparticles often leads to agglomeration on the surface of CF after sizing, consequently diminishing the material properties. In this study, the properties of cellulose nanofibers (CNFs) that can respond to magnetic and electric fields were utilized to achieve three-dimensional to one-dimensional orientations in CFs containing sizing agents. Cobalt ferrite (CoFe2O4) was utilized to enhance the response of CNFs to a magnetic field, and subsequently, it was combined with an electric field to attain a higher degree of orientation. The occurrence of nanoparticle agglomeration is diminished on CF surface, while establishing a structured network. The flexural strength and thermal conductivity of CF composites treated with CoFe2O4 self-assembled CNF sizing agent exhibit an increase of 54.23 % and 57.5 %, respectively, compared to those of desized CF composites, when subjected to magnetic and electric fields. Consequently, the approach can depolymerize the nano-fillers within the sizing agent and orient it into the carbon fiber under the influence of magnetic and electric fields, effectively improving the mechanical properties and thermal conductivity of the composite material.

The reduction of the agglomeration of silver oxide nanosolids under the influence of pressure

This project suggests an experimental methodology to diminish the agglomeration of nanoparticles by reducing the pressure. The approach considers the increase in the electrical impedance upon reducing the pressure as an indicator for the agglomeration diminishment. The impedance of a capacitive system of nanoparticles depends on the surface area. The current method has been applied on silver oxide nanoparticles thin layer prepared at our lab. At atmospheric pressure (101kPa), the impedance has been found to be higher than its value at 70 kPa (≈30kPa below ambient) by an amount that can reach four orders of magnitude at frequencies (≲20kHz). This establishes that reducing the pressure on the system decreases the impedance. This decrease indicates that the surface area increases and the twinning volumes (ε) between nanoparticles diminish and the agglomeration is reduced. This demonstrates that the agglomeration of the silver oxide nanoparticles has been reduced upon reducing the pressure.

Metronidazole degradation mechanism by sono-photo-Fenton processes using a spinel ferrite cobalt on activated carbon catalyst

A heterogeneous catalyst was prepared by anchoring spinel cobalt ferrite nanoparticles on porous activated carbon (SCF@AC). The catalyst was tested to activate hydrogen peroxide (HP) in the Fenton degradation of metronidazole (MTZ). SCF nanoparticles were produced through the co-precipitation of iron and cobalt metal salts in an alkaline condition. Elemental mapping, physico-chemical, morphological, structural, and magnetic properties of the as-fabricated catalyst were analyzed utilizing EDX mapping, FESEM-EDS, TEM, BET, XRD, and VSM techniques. The porous structure of AC enhanced the catalytic activity of SCF by a significant decrease in the agglomeration of SCF nanoparticles. The effectiveness of SCF@AC in Fenton degradation improved substantially when UV light and ultrasound (US) irradiations were induced, most likely due to the strong synergistic effect between the catalyst and these irradiation sources. The photo-Fenton system was more efficient than the Fenton, sono-, and sono-photo-Fenton processes eliminating both MTZ and TOC. It was found that AC not only dispersed SCF nanoparticles and improved the stability of the catalyst, but also provided a high adsorption capacity of MTZ, resulting in a faster degradation. After 60 min of the photo-Fenton reaction, the elimination efficiencies of MTZ (30 mg L−1) and TOC were 97 and 42.1% under optimum operational conditions (pH = 3.0, HP = 4.0 mM, SCF@AC = 0.3 g L−1, and UV = 6 W). SCF@AC showed excellent stability with low leaching of metal ions during the reaction. Radical and non-radical (O2•–, HO•, and 1O2 species), alongside adsorption and photocatalysis mechanisms, were responsible for MTZ decontamination over the SCF@AC/HP/UV system. A comprehensive study on the HP activation mechanism and MTZ degradation pathway was obtained through scavenging tests. The findings demonstrate that SCF@AC is an effective, reusable, and environmentally sustainable catalyst for advanced oxidation processes that can effectively remove organic pollutants from wastewater. This study offers valuable insights into the feasibility of employing SCF@AC catalysts in Fenton-based processes for the degradation of MTZ.

Bridging the gap between metallic MoO2 and ZnIn2S4 for enhanced photocatalytic H2 production

Noble metal-free cocatalysts have shown unprecedented potential in enhancing photocatalytic H2 evolution. However, it remains challenging to accelerate the carrier transfer rate by circuiting the substantial Schottky barrier between the metallic cocatalyst and the semiconductor. Herein, an in-situ carbonization strategy is used to accurately anchor MoO2 nanoparticles onto the surface of conductive carbon rods (MoO2/C), which serves as an efficient and stable metallic cocatalyst for ZnIn2S4 towards photocatalytic H2 evolution. The in-site derived carbon skeleton not only prevents the agglomeration of MoO2 nanoparticles thus enriching the active sites for H2 evolution, but also acts as conductor of photogenerated electrons to accelerate electron transfer. In addition, the formed Mo-S bonds at the interface provide additional electron transport channels for hierarchical core–shell MoO2/C@ZnIn2S4 (MO/C@ZIS) heterojunction. It is worth noting that the H2 evolution activity of the optimized MO/C@ZIS sample (2357 μmol·h−1·g−1) is 8.7 times higher than pure ZnIn2S4 (271 μmol·h−1·g−1), and also surpasses the activity of optimized Pt-modified ZnIn2S4 (2123 μmol·h−1·g−1). This work casts a new paradigm for the rational engineering of heterointerface between metallic cocatalysts and semiconductors towards fast electron transport and enhanced photocatalytic performance.

Enhanced Stability, Superior Anti-Corrosive, and Tribological Performance of Al2O3 Water-based Nanofluid Lubricants with Tannic Acid and Carboxymethyl Cellulose over SDBS as Surfactant

In this research work, the stability, tribological, and corrosion properties of a water-based Al2O3 nanofluid (0.5 wt%) formulated with tannin acid (TA) and carboxymethyl cellulose (CMC) as dispersants or surfactants were investigated. For comparative purposes, sodium dodecylbenzene sulfonate (SDBS) was also incorporated. The stability of the nanofluid was assessed through zeta potential measurements and photo-capturing, revealing the effectiveness of TA and CMC in preventing nanoparticle agglomeration. Tribological properties were examined using a pin-on-disk apparatus, highlighting the tribofilm of Al2O3 that enhanced lubricating properties of the nanofluid by the SEM, resulting in reduced friction and wear of the contacting surfaces. Sample with the addition of both TA and CMC exhibited the best tribological performance, with a ~ 20% reduction in the friction coefficient and a 59% improvement in wear rate compared to neat nanofluid without TA and CMC. Additionally, the corrosion resistance of the nanofluids were evaluated via weight loss and electrochemical impedance spectroscopy. The nanofluid sample containing both TA and CMC exhibited the lowest corrosion rate, with 97.6% improvement compared to sample without them. This study provides valuable insights into the potential applications of TA and CMC-based Al2O3 nanofluids as effective and environmentally friendly solutions for coolant or lubrication in cutting processes.

Green synthesis, characterization and applications of Phyllanthus emblica fruit extract mediated chromium oxide nanoparticles

The green synthesis of metallic nanoparticles is attributable towards diverse applications in various fields, recently. In this research, we report simple and eco-friendly synthesis of chromium oxide (Cr2O3) nanoparticles using the fruit extract of Phyllanthus emblica as a reducing and capping agent. The absorbance peaks at 350 nm and 450 nm validated the nanoparticle formation in UV–visible spectrum. FTIR spectrum revealed the nature of functional groups. The crystalline properties of nanoparticles were ascertained by XRD analysis. EDX spectrum corroborated the elemental composition of nanoparticles in which chromium and oxygen constituted 68% of total weight. SEM images demonstrated agglomeration of nanoparticles resulting in the formation of large irregularly shaped flakes. Cr2O3 nanoparticles demonstrated excellent antimicrobial properties against 11 bacterial isolates and 1 fungal isolate. The largest inhibition zone (53 mm) was measured against A. baumannii while the smallest inhibition zone (26 mm) was recorded against S. aureus. Minimum inhibitory concentration (MIC) values were < 1 µg/ml for all microbes. However, the synthesized nanoparticles did not reveal synergism with any of the selected antibiotics (FICI values > 1). Nanoparticles possessed potent anti-biofilm powers with maximum (77%) inhibition of E. coli biofilms and minimum (45%) inhibition of S. enterica biofilms. Photocatalytic activity of Cr2O3 nanoparticles was evaluated to determine their efficacy in environmental bioremediation. Outcomes demonstrated degradation of methyl red (84%) but not of methylene blue dye. Furthermore, the Cr2O3 nanoparticles displayed considerable antioxidant (43%) as well as anti-inflammatory (44%) potentials. Hence, the present study accounts for the versatile applications of P. emblica-mediated Cr2O3 nanoparticles which could be pursued for future biomedical and environmental applications.Graphical