Dispersion Of Powders Research Articles

Carbon dots as a sustainable electrolyte enhancer in aqueous alkaline electrochemical capacitors

In the endeavour to increase the energy density and to widen the potential window of aqueous alkaline electrochemical capacitors (EC), this study explores the role of carbon dots (CDs) as an additive in potassium hydroxide electrolyte. The CDs with an average size of ∼2.2 nm and negative surface potential are synthesized from a dispersion of palm kernel shell powder in water using a low-temperature hydrothermal process. Electrochemical measurements show that the CD–electrolyte ion (K+) interaction has improved counter ion adsorption in porous carbon electrodes via lowering the characteristic resistances and time constants, which significantly improved the fraction of adsorbed charges than diffusively stored. The improved ionic conductivity is attributed to the improved wettability introduced by the hydrophilic functional groups in the CDs. These parametric changes widened the potential window and marked an 80 % increase in the specific energy and over a 10 % increase in specific power in a practical EC with similar mass-loading as commercial devices. The device with CDs demonstrated superior cycling stability and Coulombic efficiency than the control device without them. These findings underscore the potential of CDs as a promising avenue for advancing the performance parameters of aqueous electrolyte EC, aligning with the overarching goal of realising economical, environmentally friendly, and sustainable energy storage solutions.

The Heat Flux Method for hybrid iron–methane–air flames

Recently, a cyclic energy storage concept was proposed involving the use of metal powder as CO2-free energy carrier, known as the metal fuel cycle. In this cycle, the burning of iron powder is considered as the discharge agent of the energy carrier. However, for this cycle to be an efficient one, a better understanding of the laminar burning velocity of iron powder is required. This study presents a newly developed burner based on the Heat Flux Method (HFM), which can measure the burning velocities of flat hybrid iron–methane–air flames. Since laminar iron flames are difficult to stabilize and have – even for micron-sized particles – burning velocities in close proximity to their terminal velocity, methane is used as a stabilizing agent. In this paper, the design of the new burner system is presented with results for burning velocities of iron–methane–air flames. The results show a steady decrease in burning velocity when iron is added to a stoichiometric methane–air flame down to 16 cm/s. It is hypothesized that in the case of relatively low iron concentrations, the iron acts as a heat sink within these flames, consequently reducing the flame temperature and laminar burning velocity. For these low concentrations, methane is the governing fuel. At concentrations above 250 g/m3, the reduction of the burning velocity comes to a halt, and the iron becomes the governing fuel in the flame. A comprehensive error analysis reveals that the primary sources of uncertainty stem from fluctuations in the iron content and parabolic fitting of the thermocouple measurements in the HFM.Novelty and Significance statementThe novelty of this study is a newly developed burner based on the well-known Heat Flux Method (HFM). In accordance with the HFM, a new burner was designed to facilitate stable flat adiabatic hybrid iron–methane–air flames for the first time and measure its key parameter, the adiabatic burning velocity. Further, a metered iron powder dispersion system was developed for accurate iron mass flow measurements. The results show a steady decrease in burning velocity when iron is added to a stoichiometric methane–air flame in relatively low concentrations and show a very weak dependence of the burning velocity on the iron content at iron concentrations above 250 g/m3. These findings enable the validation of 1D simulations for iron-laden flames. A detailed assessment of the measurement uncertainties reveals that the largest source of uncertainty can be derived back to the stability of iron mass flow, leading to small flame propagation fluctuations on relatively short intervals.

Aureobasidium pullulans formulations: evaluation of the effectiveness against grey mould of table grape

Antagonism against Botrytis cinerea is often carried out using yeast as direct antagonists. Aureobasidium pullulans strain AP1 was tested in two different formulations: wettable powder (WP) and oil dispersion (OD). By in vitro assays, the viability of the strain cells was constantly evaluated for seven months and the OD formulation ensured the highest cells viability. The efficacy of the formulations was assayed by evaluating the production of volatile and non-volatile metabolites. Results showed that the formulation affected the non-volatile less than the volatile metabolites. Both AP1 WP and AP1 OD non-volatile metabolites displayed almost 50% of mycelial pathogen inhibition. Comparing the two products, the lowest EC50 value (518.15 mg L− 1) was detected for the AP1 OD formulation that was thus chosen for postharvest in vivo assays. The preventative treatments (200, 400, 800 mg L− 1) were active in reducing the pathogen incidence on table grape on average by 52%. Instead, in the curative application assay, the highest concentration (800 mg L− 1) reduced grey mold incidence by 86%. The present study reported the potential of two new formulations to use against the postharvest grey mold of table grape for a possible further commercial product development.

Enhanced performance of hybrid piezo/triboelectric using BaTiO3/polymer composite film modified with rGO

ABSTRACT Hybrid piezo/triboelectric technology is an emerging energy source that can continuously power small electronic devices by harvesting ambient mechanical energy and converting it into electricity. In this work, a high-performance hybrid piezo/triboelectric device was presented. The composite film was synthesized that co-doped BaTiO3 powders (BT) and reduced graphene oxide (rGO) embedded within a host material made of polydimethylsiloxane (PDMS). The hybrid device is made by mixing BT powders into the PDMS to form a series of composite films, ranging from 10% to 45% by wt.%. Additionally, 1–5 wt.% of rGO was loaded into fabricates 40BT/PDMS. The results show that the addition of rGO can improve the uniform dispersion of BT powder in the PDMS matrix. The 4 wt.% of rGO for 40BT/PDMS exhibited the optimal energy harvesting performance among all compositions, achieving notable output voltage and current. This work demonstrates a facile, low-cost approach for obtaining high-performance hybrid piezo/triboelectric by utilizing a composite film BaTiO3 and polymer (PDMS) modified with rGO.

Powder Dispersion Technology in Cosmetics (Dispersion of UV Filters in Oils)

Powder Dispersion Technology in Cosmetics (Dispersion of UV Filters in Oils)

Pulsed laser fragmentation synthesis of carbon quantum dots (CQDs) as fluorescent probes in non-enzymatic glucose detection

Pulsed laser fragmentation in liquid (PLFL) is one of the synthesis routes for producing high-purity carbon quantum dots (CQDs) with less toxic by-products in a straightforward system. The limited literature regarding the application of PLFL-synthesized CQDs motivated this study to exploit them as fluorescent probes in glucose sensing. The design of a fluorescent-based non-enzymatic glucose sensor was achieved by implementing CQDs and 3-aminophenylboronic acid (APBA) as fluorescent probes and glucose receptors, respectively. The CQDs were fabricated by PLFL through an Nd:YAG nanosecond laser, starting from the carbon powder dispersion in ethanol. Then, a laser-assisted post-modification process with oxidizing acid was implemented to produce water-dispersible CQDs for easy functionalization. Functionalizing these CQDs with APBA (CQDs-APBA) resulted in a blue-shifted fluorescence emission with a 35% quantum yield and high photostability. The CQDs-APBA exhibited a turn-off response at increasing glucose concentrations. This method offers good sensitivity with a linear detection range of glucose with a concentration of 0.165 to 8 mM and a detection limit of 165 µM. The applicability of this sensor to real analytes such as saliva obtained a satisfactory result with good reproducibility. This work proves that CQDs synthesized from PLFL can also be an alternative fluorescent probe for fluorescent-based sensing applications.

Effect of Cetyl Trimethyl ammonium bromide (CTAB) amount on the Nanoindentation creep behaviour of Sn-cu-Y2O3 nanocomposite Lead-free solder

Sn-Cu-Y2O3 nanocomposite solder is synthesized from a citrate bath by pulse electrodeposition route. Y2O3 powder is synthesized from a sol-gel assisted combustion route. Different techniques such as SEM, XRD, and TEM are used to characterize Y2O3 powder. The particle size of Y2O3 powder is found to be 27 nm. The effect of adding cetyl trimethyl ammonium bromide (CTAB) on the synthesis of Sn-Cu-Y2O3 nanocomposite lead-free solder is studied. The amount of CTAB is varied for a particular amount of Y2O3 powder. It is carried out to find the exact ratio of CTAB for better dispersion of Y2O3 powder in the electrolytic bath. Because the distribution of reinforcement in the matrix which is associated with the dispersion of Y2O3 powder in the electrolyte is as important as the amount of reinforcement in the solder matrix. For the synthesis of nanocomposite solder, the optimum ratio of CTAB to Y2O3 is found to be 1:1. After the synthesis of nanocomposite solder, the influence of Y2O3 powder on the melting temperature of the solder is also studied. Incorporating Y2O3 has little effect on the melting point of the nanocomposite solder. Nanoindentation creep test results showed that the deposit at 0.2 A/cm2 (monolithic solder) has a lower creep resistance than the nanocomposite solders. Additionally, the creep resistance of the nanocomposite with a CTAB to Y2O3 ratio of 1:1 was higher.

Microstructure and properties of oxide-reinforced FeCrAl matrix alloy manufactured by selective laser melting

In this work, nano-Y2O3 dispersed FeCrAl powders (NYD-Fe) were used to produce oxide dispersion strengthened (ODS) alloy by selective laser melting (SLM), and their microstructures and properties were investigated in detail by the kinds of characterization techniques. The results indicate that the Y2O3 particles adhered to the surface of FeCrAl powder absorb more laser, thus increasing the laser energy demand. High quality ODS deposits can be obtained at 600 mm/s and 180 W parameters. The ODS samples deposited by SLM exhibit coarse columnar grains with [001] texture. The Ti-rich nanoparticles and core-shell structured nanoparticles (Y- and O-rich core surrounded by a Ti-rich shell) are observed in ODS alloys. The precipitation formation of core-shell structured nanoparticles involves ball milling amorphization and dissolution reprecipitation. The ODS-180 alloy exhibits a higher ductility compared to FeCrAl-180 alloy, which is caused by the cellular structure with high density dislocations and the nano-sized precipitates inhibit the dislocation motion. The wear rate of the ODS-180 alloy is 51% lower than that of FeCrAl-180 alloy, which is mainly ascribed to the hardness and interface oxide layer resulting from its specific microstructural features.

Optimisation of Synchronous Grouting Mix Ratio for Shield Tunnels

During shield construction in underground spaces, synchronous grouting slurry is poured between the surrounding rock and tunnel lining to ensure stability. For synchronous grouting slurries, few studies have investigated the relationship between the rheological parameters and physical properties, grout-segregation mechanism, and anti-segregation performance. Therefore, we explored the relationships between the slurry rheological parameters, segregation rate, and bleeding rate. Cement, sand, fly ash, and bentonite were used to prepare the slurry, and the effects of different polycarboxylate water-reducing agents and dispersible latex powder dosages were studied. The rheological parameters of 16 groups of uniformly designed slurries were tested, and the data were fit using the Herschel–Bulkley model. The optimal mix ratio lowered the slurry segregation rate, and its rheological behaviour was consistent with the Herschel–Bulkley fluid characteristics. High-yield-shear-stress synchronous grouting slurries with high and low viscosity coefficients were less likely to bleed and segregate, respectively. The optimised slurry fluidity, 3 h bleeding rate, 24 h bleeding rate, segregation rate, coagulation time, and 28 days compressive strength were 257.5 mm, 0.71%, 0.36%, 3.1%, 6.7 h, and 2.61 MPa, respectively, which meet the requirements of a synchronous grouting slurry of shield tunnels for sufficiently preventing soil disturbance and deformation in areas surrounding underground construction sites.

PERFORMANCE EVALUATION AND ECONOMIC ASSESSMENT IN ELECTRICAL DISCHARGE MACHINING OF SS316 USING GRAPHITE POWDER DISPERSED IN BIODEGRADABLE PALM OIL DIELECTRIC

In today’s rapidly evolving manufacturing industry, researchers and engineers are constantly seeking innovative methods to improve machining processes. One such area of interest is the use of electrical discharge machining (EDM) for difficult-to-machine metals like SS316. This research compares the performance and economic aspects of traditional EDM and powder-mixed EDM when machining SS316 using copper electrode. Graphite powder dispersed in biodegradable palm oil is investigated as a dielectric media with the aim of enhancing EDM performance. According to the findings, the analysis of the cutting performance of different machinability aspects revealed that using graphite powder mixed with palm oil as a dielectric in EDM outperformed conventional EDM relating to material removal, surface finish, surface hardness, electrode wear rate and hole overcut. The flushing condition and unique properties of graphite powder and palm oil, such as cooling, and thermal conductivity, contributed to the improved performance observed in EDM processes. These findings highlight the potential of graphite powder mixed with palm oil as a promising alternative dielectric in EDM, offering enhanced machining capabilities and improved surface quality. The total machining expenditure per part under PMEDM (INR 505.50) is lowered by 9.2% than expenditure under conventional EDM (INR 525). The surface microhardness of the machined component attained using graphite powder-mixed EDM is enhanced in comparison to that achieved using standard EDM due to the creation of a carbon-rich re-solidified layer.

Study on the evolutionary mechanism of shrinkage stress-strain behavior of EVA-modified cement mortar at an early age

Understanding the early deformation characteristics is important to predict early cracks in cementitious materials and to serve structural engineering. Incorporation of polyethylene-vinyl acetate (EVA) dispersible polymer powder can improve the early cracking of cementitious materials. In this paper, the homogeneity, shrinkage stress-strain behavior and the evolutionary mechanism of EVA-modified cement mortar (EMCM) with different polymer-to-cement ratios (p/c) were investigated at an early age. The homogeneity and shrinkage stress-strain behavior of EMCM were characterized by a self-designed test setup. Isothermal calorimetric analysis, scanning electron microscopy and X-ray diffraction were used for the evolutionary mechanism analysis. The results show that the homogeneity of shrinkage of EMCM can be improved by adding EVA and prolonging the mixing time. The shrinkage stress of EMCM can be reduced by 83 % when p/c is 10 % and 15 %. Meanwhile, the elastic modulus of mortar can be reduced by 45 % when the EVA content is 15 %. Isothermal calorimetric analysis and characterization of microscopic properties show that EVA can inhibit both the generation and conversion of C4AH13, as well as the generation of AFt and CH, and retard the hydration of cement mortar. Within 3 h of hydration, the change in shrinkage stress of EMCM is only affected by the amount of AFt generated, while the change in shrinkage strain is affected by both CH and AFt generation, and the correlation with CH is greater. Finally, the interpenetrating network structure between the EVA and the cementitious matrix increases the interaction and bond between them, giving good deformability and thus reducing shrinkage. Therefore, the reduction in shrinkage stress-strain of EMCM is a result of the combined effect of the polymer on delaying cement hydration and increasing internal interaction and bonding.

Mass transfer and bubble hydrodynamics in stirred tank with multiple properties fluid via a CFD‐PBM method

AbstractThe performance of a stirred bioreactor was evaluated in this study in terms of the bubble hydrodynamics and the mass transfer efficiency, using a non‐viscous Newtonian fluid of water, a viscous non‐Newtonian fluid of xanthan, and a viscous non‐Newtonian fluids of xanthan with dispersed soybean powder, respectively. The computational fluid dynamics–population balance model (CFD‐PBM) method coupled with the viscosity model and the mass transfer model is established to simulate the gas–liquid mass transfer process and bubble size distribution in the stirred bioreactor. The results demonstrate that the rheological properties of the fluid play an important role in determining the gas holdup, the mass transfer efficiency, and the bubble size distribution. Viscosity of the fluid exhibits a negative impact on gas–liquid mass transfer rate and gas holdup. Moreover, by properly adjusting the operating conditions such as the stirrer speed, it is possible to modulate the gas dispersion and mass transfer rate in the reactor.

Composite modification of fine SiC powder by 3-aminopropyl triethoxysilane and sodium polystyrene sulfonate and its slip casting study

Composite modification of fine SiC powder was implemented by 3-aminopropyl triethoxysilane (KH550) and sodium polystyrene sulfonate (PSS) to improve the dispersion stability of fine powder in water. KH550 was adopted as preliminary modifier and then PSS was used for second modification of KH550-SiC powder. Adsorption studies proved the preliminary modification of KH550 contributed to the adsorption of PSS on SiC particle surface and PSS saturated adsorption capacity was 4.473 mg/g. After KH550 and PSS composite modification, the zeta potential, stability and dispersibility of fine SiC powder were improved. The absolute value of zeta potential of KH550-PSS-SiC particle reached the maximum value of 46.4 mV at pH 12. KH550-PSS-SiC suspension had better stability at the pH range of 2–12. Subsequently, KH550-PSS-SiC powder was mixed with coarse SiC powder to prepare recrystallized SiC (RSiC) green body by slip casting. When the mass ratio of KH550-PSS-SiC powder to coarse SiC powder was 2:3, RSiC slurry with the solid loading of 70 vol% and the viscosity of 636.0 mPa s was obtained and then dense RSiC green body was produced. The density of the prepared RSiC green body was 2.6603 g/cm3 and the relative density was 82.70 %.

Highly selective granulation adsorbents for lithium recovery from gas field brine: Selectivity, kinetics and mechanism

Polyvinyl chloride (PVC)-based granulated adsorbents with high mechanical stability have proven effective for extracting lithium from salt lake brine on a commercial scale. However, granular materials with high adsorption selectivity for Na+/Li+ separation and long service life still remain a great challenge. Here, we prepared granulated spherical adsorbents by a phase conversion method using PVC as a binder; PEG, PMMA, PAN, and PAA as hydrophilic co-binders; and Li1.33Mn1.67O4 (LMO) as a powder adsorbent. Among these materials, P-PAA exhibited excellent hydrophilicity and excellent binder compatibility, facilitating the dispersion of LMO powders and ensuring high adsorption. Moreover, the mechanism of action of the PVC/PAA binders was first explored via experiments and simulations, which revealed that Li+ migration was promoted and occurred primarily on LMO rather than on binders, so nonselective adsorption decreased. Therefore, P-PAA demonstrated exceptional Li+ adsorption capacity (12.9 mg/g) and selectivity for Li+ (distribution factor of 1391.3 mL/g) over other coexisting cations and a separation factor of αNaLi= 718, which are greater than those of other adsorbents reported in the literature. Furthermore, the unique structure of P-PAA, which was obtained by interconnecting larger core pores (5–10 μm) and abundant smaller pores (0.5–1 μm), accelerated the water/ion transfer kinetics without causing powder leakage. Hence, the lifespan of these materials has been extended, as salt crystals or internal cracks did not form during long-term cyclic use, unlike in the case of other granules. All of the above factors made P-PAA effectively recover Li+ from Puguang gas brine, which contains a high sodium salt content and organic pollutants, with an efficiency of 98.4 %. All these properties demonstrate that P-PAA could be used in an appealing and competitive manner for industrial processes.

Spark plasma sintering of SiC-based bulk materials from carbonaceous residue of rice husk thermal processing

Relevance. The search for a useful application of carbonaceous residues of rice husks thermal processing. These residues due to high silicon content in the inorganic part can potentially be used to produce silicon carbide – an important functional material for various fields of science and technology. Useful utilization of this waste will allow not only solving the environmental problem associated with their inefficient application and formal disposal, but also obtaining value-added products in the form of SiC-based ceramics. Aim. To obtain SiC-based bulk products from carbonaceous residues of rice husk thermal processing by spark plasma sintering with a minimum number of additional stages of feedstock processing. Objects. SiC-based bulk products obtained using carbonaceous residues of rice husk thermal processing. The samples were obtained by spark plasma sintering at 1800 °C, pressure of 60 MPa and holding time of 10 minutes. Methods. Spark plasma sintering; X-ray diffractometry (X-ray phase analysis); scanning electron microscopy; vacuumless arc discharge synthesis method. Results. The authors have carried out the experimental studies to assess the possibility of applying carbonaceous residue of rice husk thermal processing as a precursor for the synthesis of silicon carbide in bulk (ceramics) and dispersed (powder) forms. A series of experiments on spark plasma sintering of carbonaceous residue from rice husk thermal processing in the initial and milled form, with SiO2 silica sand additives, as well as with the use of silicon carbide powders synthesized from carbonaceous residue by vacuumless arc discharge method were implemented. The latter is performed within a one-stage fast-flowing process in an air environment and does not require the use of a vacuum system. Preliminary results demonstrated the possibility of obtaining bulk products and dispersed powders based on silicon carbide with a content of at least 50 and 60 wt %, respectively, and indicate the prospects of further increasing phase purity by optimizing spark plasma sintering and vacuumless arc discharge synthesis.

Foaming Properties and Foam Structure of Milk Determined by Its Protein Content and Protein to Fat Ratio

AbstractMilk proteins, integral to stable foam production, exhibit seasonal and type-dependent variations. Understanding the impact of protein levels with and without fat on foaming properties is essential for selecting suitable milk types and controlling the foaming process. In this study, we employed steam injection and mechanical mixing to assess foamability, foam stability, and foam structure of (1) reconstituted skim milk powder dispersions (1.5–15% solids concentration, corresponding to 0.5–5.0% protein), (2) reconstituted whole milk powder and commercial whole milk dispersions (0.5% protein), and (3) whole milk with added skim milk powder and milk protein concentrate (3.5 and 4% protein) and butter milk powder (0.5 and 1% total solid content). Results reveal that increasing solids concentration from 1.5 to 15% significantly increased lactose content, viscosity, and surface tension. However, these changes did not impact foamability or foam stability, while slightly decreasing air bubble size. At 0.5% protein, skim milk powder dispersions demonstrated higher foam volume (16 times greater) and more stable foam compared to reconstituted whole milk powder and whole milk dispersions, despite similar foam structure and appearance. These findings emphasize the substantial influence of the protein/fat ratio on milk’s foaming properties. Additionally, the addition of skim milk powder, milk protein concentrate, or butter milk powder at the investigated content did not affect the foaming properties of whole milk.

Preliminary Study and Use of Design of Dusto Cleaner for Black Board

Even if we lead to the digital platform traditional chalk and board is an integral part of the education life. Blackboards and chalk pieces are used in almost every educational field in the world. Cleaning the board using a duster is essential for continuing the writing process and this involves rubbing a sponge surface against the board surface. This cleans the board but also creates a fine dispersion and particles of chalk powder around the atmosphere nearer the board, which is certain to be inhaled by the teachers, and in many cases, students who occupy seats near the blackboard suffer some inhalation problems. The work also stated that teachers were at the maximum risk of inhaling the chalk dust and may suffer from respiratory diseases. Key Words: Blackboard, chalk, duster, respiratory, diseases

Efficacy of Ga3+ ions on structural, biological and antimicrobial activity of mesoporous lithium silicate bioactive glasses for tissue engineering

Mesoporous bioactive glass nanoparticles (MBGNPs) containing therapeutic ions have shown significant promise in the realm of hard and soft tissue repair and regeneration, owing to their multifunctional biological properties. In this study, gallium-incorporated silica-based gallium incorporated MBGNPs (Ga-MBGNPs) with fixed amount of Li2O (8 mol %) were synthesized using an emulsion-assisted sol-gel method. The impact of Ga2O3 integration into the silicate glass network was evaluated by investigating the microtextural properties. The results confirmed the production of spherical-shaped, nano-sized, amorphous particles with an enhanced specific surface area and ordered hexagonal meso-porosity (10–20 nm) in the developed Ga-MBGNPs. The in vitro bioactivity, assessed through hydroxyapatite (HAp) layer formation in simulated body fluid (SBF), over varying time intervals (0, 1, 3, 7, 14 & 21 days), revealed pronounced formation of short rod-like carbonated HAp with increasing immersion time and Ga3+ content in all glasses. However, a delayed apatite formation was observed for composition-dependent Ga-4 and Ga-5 MBGs during the initial incubation periods (1, 3, and 7 days). Further, the presence of Li + ions along with Ga3+ enhanced the apatite deposition when compared with the only Ga3+ inclusion. Evaluation of degradation rate and pH values indicated enhanced apatite formation with lower Ga ion content, while a slight reduction was noted with higher Ga ion content, attributable to the presence of reactive Si–O–Si bonds. Furthermore, analysis using a Zeta potential analyzer confirmed the dispersibility and bioreactivity of all glass powders owing to their higher negative surface charge. Moreover, Ga-MBGNPs exhibited notable antimicrobial effects against both E. coli and S. aureus bacteria due to the release of Ga3+ ions. Overall, the findings suggest that the incorporation of Ga in MBGNPs renders them potential multifunctional candidates for expediting the healing of bone tissue injuries in biomedical applications.

Controllable preparation of black phosphorus nanomaterials via liquid-phase pulsed discharge

The N, N-dimethylformamide (DMF) organic solvent was deliberately chosen as the optimal medium for this investigation. To achieve uniform dispersion of black phosphorus powder, which was obtained via shock-induced phase transformation, it was effectively dispersed in the DMF solution, resulting in a homogeneous black phosphorus-DMF suspension. Subsequently, a liquid-phase pulsed discharge experiment was conducted. This experimental setup harnessed the shockwave and tensile stripping effects generated by the rapid expansion of plasma during the liquid-phase pulsed discharge. These phenomena facilitated the interlayer exfoliation and dispersion of black phosphorus molecules, ultimately leading to the formation of a suspension containing black phosphorus quantum dots. In-depth investigation into the formation mechanism of black phosphorus quantum dots was also undertaken. Our findings reveal a pivotal influence of the charging voltage on the microstructure of the recovered samples. Specifically, as the charging voltage increases, the lateral dimensions of the retrieved two-dimensional black phosphorus powder undergo a remarkable reduction, transitioning from the micron-scale to less than 10 nm. The above results, which stem from meticulous experimentation and analysis, emphasize the significance of controlled synthesis in producing black phosphorus quantum dots with varying microstructures. Such insights hold substantial promise for advancing the field of materials science and enhancing the applicability of black phosphorus quantum dots in diverse applications.

Effect of Copper Particle Size on the Surface Structure and Catalytic Activity of Cu–CeO2 Nanocomposites Prepared by Mechanochemical Synthesis in the Preferential CO Oxidation in a H2-Rich Stream (CO-PROX)

An effect of Cu powder dispersion and morphology on the surface structure and the physical–chemical and catalytic properties of Cu–CeO2 catalysts prepared by mechanochemical synthesis was studied in the preferential CO oxidation in a H2-rich stream (CO-PROX). Two catalysts, produced by 30 min ball-milling from CeO2 and 8 mass% of copper powders and with particle sizes of several tens (dendrite-like Cu) and 50–200 nm (spherical Cu obtained with levitation-jet method), respectively, were characterized by X-ray diffraction and electron microscopy methods, a temperature-programmed reduction with CO and H2, and with Fourier-transform infrared spectroscopy. The catalyst synthesized from the “large-scale” dendrite-like Cu powder, whose surface consisted of CuxO (Cu+) agglomerates located directly on the surface of facetted CeO2 crystals with a CeO2(111) and CeO2(100) crystal planes exposition, was approximately two times less active at 120–160 °C than the catalyst synthesized from the fine Cu powder, whose surface consisted of CuxO (Cu2+) clusters of 4–6 nm in size located on the steps of facetted CeO2 nanocrystals. Although a large part of CO2 reacted with a ceria surface to give carbonate-like species, no blockage of CO-activating centers was observed due to the surface architecture. The surface structure formed by the use of highly dispersed Cu powder is found to be a key factor responsible for the catalytic activity.