Agglomeration Of Nanoparticles Research Articles

Sustainable Synthesis of Novel Green-Based Nanoparticles for Therapeutic Interventions and Environmental Remediation.

The advancement in nanotechnology has completely revolutionized various fields, including pharmaceutical sciences, and streamlined the potential therapeutic of many diseases that endanger human life. The synthesis of green nanoparticles by biological processes is an aspect of the newly emerging scientific field known as "green nanotechnology". Due to their safe, eco-friendly, nontoxic nature, green synthesis tools are better suited to produce nanoparticles between 1 and 100 nm. Nanoformulation of different types of nanoparticles has been made possible by using green production techniques and commercially feasible novel precursors, such as seed extracts, algae, and fungi, that act as potent reducing, capping, and stabilizing agents. In addition to this, the biofunctionalization of nanoparticles has also broadened its horizon in the field of environmental remediation and various novel therapeutic innovations including wound healing, antimicrobial, anticancer, and nano biosensing. However, the major challenge pertaining to green nanotechnology is the agglomeration of nanoparticles that may alter the surface topology, which can affect biological physiology, thereby contributing to system toxicity. Therefore, a thorough grasp of nanoparticle toxicity and biocompatibility is required to harness the applications of nanotechnology in therapeutics.

Performance Enhancement of Ti/IrO2-Ta2O5 Anode through Introduction of Tantalum-Titanium Interlayer via Double-Glow Plasma Surface Alloying Technology.

Ti/IrO2-Ta2O5 electrodes are extensively utilized in the electrochemical industries such as copper foil production, cathodic protection, and wastewater treatment. However, their performance degrades rapidly under high current densities and severe oxygen evolution conditions. To address this issue, we have developed a composite anode of Ti/Ta-Ti/IrO2-Ta2O5 with a Ta-Ti alloy interlayer deposited on a Ti substrate by double-glow plasma surface alloying, and the IrO2-Ta2O5 surface coating prepared by the traditional thermal decomposition method. This investigation indicates that the electrode with Ta-Ti alloy interlayer reduces the agglomerates of precipitated IrO2 nanoparticles and refines the grain size of IrO2, thereby increasing the number of active sites and enhancing the electrocatalytic activity. Accelerated lifetime tests demonstrate that the Ti/Ta-Ti/IrO2-Ta2O5 electrode exhibits a much higher stability than the Ti/IrO2-Ta2O5 electrode. The significant improvement in electrochemical stability is attributed to the Ta-Ti interlayer, which offers high corrosion resistance and effective protection for the titanium substrate.

A self-excitation point process model for quantifying nanoparticle agglomeration

ABSTRACT Nanoparticle agglomeration refers to the spontaneous clustering of nanoparticles caused by the attractive forces. Agglomeration impacts the physical and mechanical properties of nanoparticles and their composites. Understanding and controlling nanoparticle agglomeration is crucial for optimizing various applications, from nanomedicine to nanoelectronics. In this work, we formulated a self-exciting point process model to analyse nanoparticle agglomeration based on microstructural input. The model is utilised to categorise a specific set of points within the microstructure as either independent (dispersed) or dependent (agglomerated), along with their respective probabilities. We employed this approach to study two distinct scenarios: (a) Agglomeration in experimentally generated microstructures of titanium nanoparticles, and (b) Analysing agglomeration patterns in simulated microstructures of carbon nanotube networks, generated using a stochastic microstructure model. We obtain a quantitative understanding of the connection between the sonication duration and the level of agglomeration in titanium nanoparticles. As the sonication period increases, both the agglomeration percentage and the size of the agglomerates decrease. Furthermore, our analysis of simulated carbon nanotube microstructures, including equiaxed and rope-like agglomeration, shows a close alignment between results obtained from the point process model and those generated by the stochastic microstructure model.

Volcanic Eruption in the Nanoworld: Efficient Oxygen Exchange at the Si/SnO2 Interface.

Here, a phenomenon of efficient oxygen exchange between a silicon surface and a thin layer of tin dioxide during chemical vapor deposition is presented, which leads to a unique Sn:SiO2 layer. Under thermodynamic conditions in the temperature range of 725-735°C, the formation of nanostructures with volcano-like shapes in "active" and "dormant" states are observed. Extensive characterization techniques, such as electron microscopy, X-ray diffraction, synchrotron radiation-based X-ray photoelectron, and X-ray absorption near-edge structure spectroscopy, are applied to study the formation. The mechanism is related to the oxygen retraction between tin(IV) oxide and silicon surface, leading to the thermodynamically unstable tin(II)oxide, which is immediately disproportionate to metallic Sn and SnO2 localized in the SiO2 matrix. The diffusion of metallic tin in the amorphous silicon oxide matrix leads to larger agglomerates of nanoparticles, which is similar to the formation of a magma chamber during the natural volcanic processes followed by magma eruption, which here is associated with the formation of depressions on the surface filled with metallic tin particles. This new effect contributes a new approach to the formation of functional composites but also inspires the development of unique Sn:SiO2 nanostructures for diverse application scenarios, such as thermal energy storage.

Influence of the temperature-induced ordered-disordered phases for iron difluoride on the electrochemical performance

Iron difluoride (FeF2) is one of the promising cathodes to achieve high energy-density lithium-ion batteries (LIBs). However, the sluggish ion transportation kinetics in the FeF2 bulk phase may cause large voltage hysteresis and lower cell efficiency, which hinders its commercial adoption. Introducing a disordered phase into the ordered bulk FeF2 is proposed to promote ion transportation and increase ion diffusion channels. Here, varying ratios of the disordered phase are incorporated into the ordered matrix of FeF2 by adjusting the annealed temperatures. The ion transportation is improved due to the optimal ratio of the disordered to ordered (RDO) phase. Among four electrodes, the RDO25% electrode demonstrates the least electrochemical polarization of 1.22 V and the lowest voltage hysteresis of about 1.0 V, in addition to delivering a discharge capacity of 128 mAh g−1 after 100 cycles in the carbonate-type electrolyte. The introduction of the disordered phase enables FeF2 to exhibit a distinct intercalation and conversion dual-mechanism cathode. Additionally, appropriate ratios of the disordered-ordered phase can mitigate nanoparticle agglomeration, establish a conformal cathode electrolyte interface (CEI), reduce interfacial resistance, and thereby enhance ion transport.

Enhanced electrocatalytic biomass oxidation at low voltage by Ni2+-O-Pd interfaces

Challenges in direct catalytic oxidation of biomass-derived aldehyde and alcohol into acid with high activity and selectivity hinder the widespread biomass application. Herein, we demonstrate that a Pd/Ni(OH)2 catalyst with abundant Ni2+-O-Pd interfaces allows electrooxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid with a selectivity near 100 % and 2, 5-furandicarboxylic acid yield of 97.3% at 0.6 volts (versus a reversible hydrogen electrode) in 1 M KOH electrolyte under ambient conditions. The rate-determining step of the intermediate oxidation of 5-hydroxymethyl-2-furancarboxylic acid is promoted by the increased OH species and low C–H activation energy barrier at Ni2+-O-Pd interfaces. Further, the Ni2+-O-Pd interfaces prevent the agglomeration of Pd nanoparticles during the reaction, greatly improving the stability of the catalyst. In this work, Pd/Ni(OH)2 catalyst can achieve 100% 5-hydroxymethylfurfural conversion and >90% 2, 5-furandicarboxylic acid selectivity in a flow-cell and work stably over 200 h under a fixed cell voltage of 0.85 V.

Electrochemical oxidative dehydrogenation of ethane to ethylene in a solid oxide electrolysis cell with in situ grown metal-oxide interface active electrodes

The shale gas revolution bolsters ethane supply, thereby enhancing the economic viability of ethylene production from ethane. Presently, catalytic ethane dehydrogenation technology exhibits immense potential in the realm of ethylene production. This study achieves the electrochemical oxidative dehydrogenation conversion of ethane to ethylene via a solid oxide electrolysis cell (SOEC), effectively circumventing the issue of excessive oxidation during the ethane oxidative dehydrogenation process. An active electrode with an in situ grown metal-oxide interface significantly promotes the activation of the ethane C–H bond, leading to efficient ethylene production. Under the co-electrolysis mode of ethane with CO2, the Co@CeO2 electrode demonstrates exceptional performance, achieving an ethane conversion rate of 33.1% and an ethylene selectivity of 88.9% at an applied voltage of 1.0 V. Moreover, the metal-oxide interface constructed via an in situ exsolved method effectively prevents the agglomeration of nanoparticles at high temperatures, thus enhancing the catalyst's resistance to coking and stability. Notably, the electrode's performance does not exhibit significant degradation even after 100 h of electrochemical reaction.

Sequential Deposition of Diluted Aqueous SnO2 Dispersion for Perovskite Solar Cells

The widespread use of tin dioxide (SnO2) thin films as electron transport layer (ETL) of perovskite solar cells (PSCs) has been facilitated by commercial SnO2 nanocolloid dispersion. Nevertheless, challenges such as nanoparticle agglomeration have emerged, impacting film quality and interface properties critical for PSC performance. Herein, the efficacy of sequential, multistep spin‐coating of repeatedly diluted SnO2 aqueous suspension as a simple and effective approach to enhance ETL properties is explored. Through systematic experiments using dynamic light scattering, cyclic voltammetry, optical spectroscopy, and photoconductivity, it is demonstrated that the sequential deposition significantly improves the flatness and coverage of SnO2, leading to improved electron transport and transfer from a perovskite layer. Such a synergetic effect enables to fabricate lead iodide PSC (FAPbI3, FA: formamidinium) with a power conversion efficiency of 22.99% compared to 20.48% for the conventional 1‐step SnO2 layer. The findings underscore the potential of sequential SnO2 deposition as a promising technique for robust SnO2 films of photoelectric conversion devices.

Harnessing Liquid Metals with In Situ Polymerized Electrolyte for Anode‐Free Lithium Metal Batteries

AbstractTo enhance safety and energy density in conventional Li‐ion batteries, anode‐free or zero‐lithium configurations using only a current collector (CC) in the anode have emerged. However, challenges including rapid Li dendrite growth, low Coulombic efficiency, safety concerns, and thickness issues hinder the practical use of anode‐free batteries (AFBs) with liquid electrolytes (LEs) or solid electrolytes (SEs). Herein, potential AFBs using an anode current collector coated with a liquid metal (LM)@C nanocomposite with an in situ polymerized electrolyte (PE) are reported. Interestingly, LM nanoparticles added to the composite layer on CC play a crucial role in promoting uniform Li plating/stripping behavior through a self‐healing mechanism, along with reversible liquid–solid–liquid phase transitions caused by alloying and de‐alloying of Li and LMs. Furthermore, incorporating in situ polymerized electrolytes stabilizes LMs by preventing the agglomeration of LM nanoparticles, resulting in significantly improved cell performance compared to other conventional LEs. A systematical model study with ex situ analysis unveils the synergetic effects between LMs and PE, along with elucidating the mechanism of in situ polymerization and Li‐LMs reactions. The investigation contributes valuable insights for future studies on practical applications of AFBs using polymer electrolytes and composite interlayers.

Antibacterial Effect of Silver Nanoparticles against Oral Biofilms in Subjects with Motor and Intellectual Disabilities.

Motor and intellectual disabilities (MIDs) represent a great challenge for maintaining general health due to physical and cognitive limitations, particularly in the maintenance and preservation of oral health. Silver nanoparticles (AgNPs) have emerged as a promising therapeutic tool for bacterial control, including oral biofilms; however, knowledge of the bactericidal effectiveness of oral biofilms from patients with MIDs is insufficient. This study aims to determine the antimicrobial effect of AgNPs on different oral biofilms taken from patients with and without MIDs. Two sizes of AgNPs were prepared and characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Through consecutive sampling, biofilm samples were collected from 17 subjects with MIDs and 20 subjects without disorders. The antimicrobial effect was determined by obtaining the minimum inhibitory concentration (MIC) of AgNPs, and the identification and distribution of oral bacterial species were determined by polymerase chain reaction (PCR). Finally, correlations between sociodemographic characteristics and the antimicrobial levels of AgNPs were also explored. The values of the MIC results were analyzed with IBM-SPSS software (version25) using non-parametric tests for independent groups and correlations, with statistical significance being considered as p < 0.05. Both sizes of AgNPs exhibited tight particle size distributions (smaller: 10.2 ± 0.7 nm; larger: 29.3 ± 2.3 nm) with zeta potential values (-35.0 ± 3.3 and -52.6 ± 8.5 mV, respectively) confirming the stability that resulted in little to no agglomeration of nanoparticles. Although both sizes of AgNPs had good antimicrobial activity in all oral biofilms, the smallest particles had the best antimicrobial effects on the oral biofilm samples from patients with and without MIDs, even better than chlorhexidine (CHX) (p < 0.05). Likewise, the patients with disabilities showed higher levels of antimicrobial sensitivity to AgNPs compared with CHX (p < 0.05). Although the microorganisms included in the biofilms of females had a statistically higher growth level, the AgNP antimicrobial effect was statistically similar in both genders (p > 0.05). The most frequent bacteria for all oral biofilms were S. mutans (100%), P. intermedia (91.6%), T. forsythia (75.0%), T. denticola (75.0%), P. gingivalis (66.6%), F. nucleatum (66.6%), S. sobrinus (50.0%), and A. actinomycetemcomitans (8.3%). AgNPs exhibited considerable antimicrobial potential to be used as a complementary and alternative tool in maintaining and preserving oral health in patients with MIDs.

Synthesis of SrAl2O4: Eu, DY @ polymer composite membrane using eugenol as a cross-linking agent to minimize nanoparticle agglomeration

Synthesis of SrAl2O4: Eu, DY @ polymer composite membrane using eugenol as a cross-linking agent to minimize nanoparticle agglomeration

Co3+ Doped CdFe2O4 Nanoparticles: Structural, Optical, Magnetic, and Electrical Properties

Through the citrate-gel auto-combustion technique, we synthesized Co-doped cadmium nano ferrites (NFs) with the formula CoxCd1−xFe2O4 (where 0 ≤ x ≤ 1.0 with increments of 0.2). The synthesized materials underwent comprehensive analysis utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy. Magnetic and electrical properties were evaluated using a vibrating sample magnetometer and LCR meter, respectively. XRD analysis confirmed the spinel phase structure and FD3M space group. SEM analysis revealed agglomerations of nanoparticles and grain boundaries. Elemental analysis of the synthesized nanomaterials was provided by energy dispersive spectroscopy. FTIR spectroscopy identified two main broad bands corresponding to the tetrahedral (A) and octahedral (B) sites, confirming the spinel structure. Magnetic properties such as magnetic saturation, coercivity, and remanent magnetization were characterized using VSM. Additionally, the LCR meter assessed frequency and temperature-dependent dielectric parameters, including AC conductivity (σAC), dielectric permittivity, dielectric loss (tan δ), and impedance spectra. An increase in AC conductivity (σAC) was observed with increasing temperature and frequency.

INVESTIGATION OF STABILITY OF TiO2-BASED NANOFLUIDS FOR POTENTIAL USE IN HYBRID SOLAR COLLECTORS

The use of nanofluids in the cooling system of hybrid solar collectors is an urgent task of intensification of heat transfer. This heat carrier allows for more efficient cooling of the surface of the solar panel, which increases the productivity of the collector. However, the low stability of the nanofluid, manifested in the agglomeration of nanoparticles and their subsequent precipitation, affects the deterioration of the thermophysical properties. This article discusses the sedimentation process of TiO2-double distilled water nanofluid stabilized with CTAB and SDBS surfactants. The sedimentation process was monitored by UV-vis spectroscopy. A high stabilizing effect was observed with the use of CTAB surfactant, expressed in a low sedimentation rate compared to use of SDBS.

The mechanism of gold nanoparticle-enhanced corrosion acceleration of polylactide (PLA)-coated biodegradable iron and zinc

The commercial application of biodegradable metals (BMs), such as iron (Fe) and zinc (Zn), is hampered by their slow degradation rate. Polylactide (PLA) coatings on BMs have been proven to accelerate the corrosion of Fe and Zn but with limited success. This is the first study exploring the use of gold nanoparticles (Au NPs) to enhance and control the corrosion of polylactide (PLA)-coated Fe and Zn. The Au NPs enhanced the corrosion rate of Fe and Zn by promoting micro-galvanic corrosion after nanoparticle agglomeration. The optimal corrosion acceleration depended on the polymer's molecular weight, coating thickness, and coating structure. The results suggest that the Au-reinforced PLA-based coatings can be used to control Fe and Zn corrosion rates in the physiological environment.

A popcorn-inspired strategy for compounding graphene@NiFe2O4 flexible films for strong electromagnetic interference shielding and absorption

Compounding functional nanoparticles with highly conductive and porous carbon scaffolds is a basic pathway for engineering many important functional devices. However, enabling uniform spatial distribution of functional particles within a massively conjugated, monolithic and mesoporous structure remains challenging, as the high processing temperature for graphitization can arouse nanoparticle ripening, agglomerations and compositional changes. Herein, we report a unique “popcorn-making-mimic” strategy for preparing a highly conjugated and uniformly compounded graphene@NiFe2O4 composite film through a laser-assisted instantaneous compounding method in ambient condition. It can successfully inhibit the unwanted structural disintegration and mass loss during the laser treatment by avoiding oxidation, bursting, and inhomogeneous heat accumulations, thus achieving a highly integrated composite structure with superior electrical conductivity and high saturated magnetization. Such a single-sided film exhibits an absolute shielding effectiveness of up to 20906 dB cm2 g−1 with 75% absorption rate, superior mechanical flexibility and excellent temperature/humidity aging reliability. These performance indexes signify a substantial advance in EMI absorption capability, fabrication universality, small form-factor and device reliability toward commercial applications. Our method provides a paradigm for fabricating sophisticated composite materials for versatile applications.

Development of Bioactive Hybrid Poly(lactic acid)/Poly(methyl methacrylate) (PLA/PMMA) Electrospun Fibers Functionalized with Bioglass Nanoparticles for Bone Tissue Engineering Applications.

Hybrid scaffolds that are based on PLA and PLA/PMMA with 75/25, 50/50, and 25/75 weight ratios and functionalized with 10 wt.% of bioglass nanoparticles (n-BG) were developed using an electrospinning technique with a chloroform/dimethylformamide mixture in a 9:1 ratio for bone tissue engineering applications. Neat PLA and PLA/PMMA hybrid scaffolds were developed successfully through a (CF/DMF) solvent system, obtaining a random fiber deposition that generated a porous structure with pore interconnectivity. However, with the solvent system used, it was not possible to generate fibers in the case of the neat PMMA sample. With the increase in the amount of PMMA in PLA/PMMA ratios, the fiber diameter of hybrid scaffolds decreases, and the defects (beads) in the fiber structure increase; these beads are associated with a nanoparticle agglomeration, that could be related to a low interaction between n-BG and the polymer matrix. The Young's modulus of PLA/PMMA/n-BG decreases by 34 and 80%, indicating more flexible behavior compared to neat PLA. The PLA/PMMA/n-BG scaffolds showed a bioactive property related to the presence of hydroxyapatite crystals in the fiber surface after 28 days of immersion in a Simulated Body Fluids solution (SBF). In addition, the hydrolytic degradation process of PLA/PMMA/n-BG, analyzed after 35 days of immersion in a phosphate-buffered saline solution (PBS), was less than that of the pure PLA. The in vitro analysis using an HBOF-1.19 cell line indicated that the PLA/PMMA/n-BG scaffold showed good cell viability and was able to promote cell proliferation after 7 days. On the other hand, the in vivo biocompatibility evaluated via a subdermal model in BALC male mice corroborated the good behavior of the scaffolds in avoiding the generation of a cytotoxic effect and being able to enhance the healing process, suggesting that the materials are suitable for potential applications in tissue engineering.

Enhancing photodetection performance through laser fluence control: SnO2 nanostructured deposited on porous silicon

In this study, we have covered a porous silicon (PS) layer with tin dioxide (SnO2) nanostructured via a pulsed laser deposition process to produce a broadband photoresponse device. The impact of laser fluence on the optical, electrical, and structural characteristics of the fabricated photodetector was identified. The optical features analysis indicated that the SnO2 films covered on porous silicon have a direct energy gap varying from 3.62 to 3.67 eV as a function of laser fluence. The X-ray diffraction investigation proved that the SnO2 nanostructure has a tetragonal rutile nature. The Field-emission scanning electron microscopy emphasised that produced SnO2 nanostructures have a mean size of 81.76–98.68 nm, and nanoparticle agglomeration was remarked. The photoluminescence emissions of SnO2 nanostructure placed on porous silicon displayed a variety of overlapping intensities in the near-ultraviolet/visible spectrum between 369 and 506 nm, while the intense red band decreased in intensity and shifted towards longer wavelengths. Fourier-transformed infrared spectroscopy investigation indicates the existence of the Sn-O-Si bond in the formed structure.The dependence of the optoelectronic characteristics of PS/n-Si and SnO2/PS/n-Si photodetector on laser fluence has been performed. Produced heterojunctions have remarkable rectification properties with ideality factors ranging from 2.27 to 2.91, relying on the laser fluence. The spectral responsivity analysis showed that SnO2/PS/n-Si photodetectors exhibit three response bands at ∼366 nm, ∼621 nm, and ∼806 nm, regarding the highest responsivity of 0.21 A/W, 0.33 A/W, and 0.43 A/W, respectively. The findings suggest that SnO2/PS/n-Si heterojunction photodetectors are suitable for developed ultraviolet–visible light detection enhanced photodiodes that are cost-effective and convenient for use in wearable and portable devices without expensive extra gadgets.

Effect of ball milling time on Sr0.7Sm0.3Fe0.4Co0.6O2.65 perovskites and their application as semiconductor layers in dye-sensitized solar cells

The practical utilization of TiO2 as a semiconductor in dye-sensitized solar cells (DSSCs) has been set back by poor visible light absorption, high charge carrier recombination, and low electrical conductivity, which reduce the power conversion efficiency (PCE) and sustainability of the device. In this respect, perovskites with excellent properties, such as large surface area, good optical properties, high electrical conductivity, and superior electrochemical stability, have recently emerged as promising alternatives capable of overcoming the drawbacks of TiO2. Herein, Sr0.7Sm0.3Fe0.4Co0.6O2.65 (SSFC) perovskites were prepared via the ball milling method at various milling times of 0, 5, and 10 h, and the obtained samples were denoted by SSFC-0, SSCF-5, and SSCF-10, respectively. Increasing the ball milling time led to a significant reduction in nanoparticle size and agglomeration, which, in turn, increased the surface area and electrical conductivity of the samples. As a consequence, the SSFC-10 perovskite exhibited the smallest average particle sizes (18.9 nm) with the largest surface area (61.8 m2 g−1) and minimum defects, which allowed for efficient electron transport, resulting in the best electrical conductivity of 49.8 S cm−1. Ultimately, DSSCs fabricated using SSFC-10 semiconductor layers achieved an optimum PCE of 6.01 %, which is an improvement of 8.67 %, 1.1 %, and 6.56 % for SSFC-0 (3.69 %), SSFC-5 (4.96 %), and TiO2 (5.64 %), respectively. Thus, varying the ball milling time can be used as an effective technique to tailor the physicochemical properties of SSFC to suit desired applications, particularly the fabrication of highly efficient and sustainable DSSC semiconductor layers.

Flow Behavior of Nanoparticle Agglomerates in a Fluidized Bed Simulated with Porous-Structure-Based Drag Laws.

Fluidization bed reactor is an attractive method to synthesize and process quantities of functional nanoparticles, due to the large gas-solid contact area and its potential scalability. Nanoparticles fluidize not individually but as a form of porous agglomerates with a typical porosity above 90%. The porous structure has a significant effect on the hydrodynamic behavior of a single nanoparticle agglomerate, but its influence on the flow behavior of nanoparticle agglomerates in a fluidized bed is currently unclear. In the present study, a drag model was developed to consider the porous structure effects of nanoparticle agglomerates by incorporating porous-structure-based drag laws in the Eulerian-Eulerian two-fluid model. Numerical simulations were performed from particulate to bubbling fluidization state to evaluate the applicability of porous-structure-based drag laws. Results obtained for the minimum fluidization and bubbling velocities, bed expansion ratio, and agglomerate dispersion coefficient show that, compared with the drag law of solid sphere, the porous-structure-based drag laws, especially the drag law of fractal porous spheres, provide a closer fit to the experimental data. This indicates that the pore structures have a great impact on gas-solid flow behavior of nanoparticle agglomerates, and the porous-structure-based drag laws are more suitable for describing flows in nanoparticle agglomerate fluidized beds.

The promotion effect of Ru on catalytic activity and stability of Ni/Co-Al2O3 catalysts for simulated diesel steam reforming

In this work, Ru is incorporated into Ni/Co to synthesize novel Al2O3-supported Ni-Ru/Co-Ru bimetallic catalysts. Tests verify their enhanced catalytic capability and durability and also reveal how each catalyst is deactivated. SEM and EDS results indicate that nanoparticle agglomeration on Ni-based surface triggers deactivation, and TG and XPS results suggest carbon deposition is fatal to Co-based catalysts. Implementing Ru effectively enhances catalytic activity and durability. To gain insight into the promoting effect of Ru, quantum mechanical methods are utilized to investigate the shifts in activation energies (Ea) in CHx* dehydrogenation processes on (111) surfaces. For the Ni catalyst, DFT calculations indicate that adding Ru decreases Ea yet does not change the determining step. In contrast, adding Ru on the Co surface changes the major intermediates from CH* to CH2*, which inhibits further dehydrogenation, and hence mitigates carbon deposition to preserve the catalytic activity of the surface.