Nickel Nanoclusters Research Articles

A Simple and Efficient Turn‐Off Fluorescence Sensor for the Nanomolar Detection of Homovanillic Acid Using Protein Mediated Blue Emitting Nickel Nanoclusters

AbstractHomovanillic acid (HVA) is a catecholamine metabolite that plays a vital role in the diagnosis of several neurological disorders. Thus, a simple and cost‐effective sensing strategy for HVA determination is significant. Herein, we describe the development of a turn‐off fluorescence sensor for the effective determination of HVA using bovine serum albumin stabilized nickel nanoclusters (BSA NiNCs). This biocompatible and water‐suspended fluorophore exhibited strong emission at 405 nm upon exciting at 325 nm. The fluorescence intensity of BSA NiNCs was efficiently quenched by the addition of HVA within the linear range 9.00×10−7 M–5.00×10−8 M with a limit of detection of 9.23×10−9 M. A static quenching mechanism was proposed for the sensor due to the aggregation of BSA NiNCs on adding HVA. The practical utility of the sensor was tested in artificial urine and blood serum and a good recovery using the spike‐recovery method were obtained.

ReaxFF Molecular Dynamics Simulation of the Cracking of Components of Vacuum Gasoil in the Presence of a Nickel Nanocluster

ReaxFF molecular dynamics simulation of the cracking of the paraffin, naphthene, and aromatic components of vacuum gasoil with and without a Ni468 nanoparticle is performed. It is found that the observed routes of destruction of hydrocarbons under thermal action do not contradict the real mechanisms of thermal cracking; the enthalpies of the thermal destruction reactions of the model components obtained in ReaxFF with the CHO and NiCH force fields correlate with those determined via quantum chemistry in the ub3lyp/6-31g(d,p) DFT approximation. The mechanisms of adsorption and destruction of the paraffin, naphthene, and aromatic components of vacuum gasoil on the surface of a Ni468 nanoparticle are studied, based on the results from ReaxFF molecular dynamics simulation. Their enthalpies of adsorption and dehydrogenation are calculated, along with the activation energies of dehydrogenation on the surface of a nickel nanoparticle. Cracking in a multicomponent system consisting of 93 hydrocarbon molecules and a Ni468 nanocluster is simulated, and all routes of the destruction of the initial hydrocarbons are determined.

Molecular dynamics simulation study on thermodynamical properties of Cu and Ni nanocluster

Metal nanoclusters are recently gaining a great deal of attraction due to their unique properties. In this work, the thermodynamical properties of copper and nickel nanoclusters has been investigated by using classical molecular dynamics simulations in combination with the second nearest neighbour modified embedded-atom-method potential parameters. Nanoclusters containing 500 atoms for both the metals have been considered for this study. The potential energy, mean square displacement, self-diffusion coefficients, and specific heat of the nanoclusters are calculated. The variation in these properties with respect to temperature has been used to define the physical phase and to determine the melting profile for each nanocluster. The melting point temperature of the Cu nanocluster is estimated to be 1150 K ± 5 K and that of the Ni nanocluster is 1460 K ± 5 K. Melting point temperatures of the nanoclusters are smaller than their bulk counterparts. The two-state model of phase transition phenomena is observed. The quantitative data for self-diffusion coefficients and specific heat at various temperatures have been obtained.

Reversible polymorphic structural transition of crown-like nickel nanoclusters and its effect on conductivity

We report the reversible polymorphic phase transition of [Ni6(PET)12] (PET = phenylethanethiol) and its effect on the conductivity. This cluster's self-assembly leads to two polymorphic structures with distinct conductivity, caused by variation of the non-covalent SS interactions. These results enlighten the effect of non-covalent interactions on conductivity.

High-performance diluted nickel nanoclusters decorating ruthenium nanowires for pH-universal overall water splitting

The diluted nickel nanoclusters-enhanced strategy has been successfully proposed that gives an optimal thermodynamic effect for enhancing the electron-transfer capability, with superior performance for pH-universal overall water splitting.

Enhanced and stabilized hydrogen production from methanol by ultrasmall Ni nanoclusters immobilized on defect-rich h-BN nanosheets

Employing liquid organic hydrogen carriers (LOHCs) to transport hydrogen to where it can be utilized relies on methods of efficient chemical dehydrogenation to access this fuel. Therefore, developing effective strategies to optimize the catalytic performance of cheap transition metal-based catalysts in terms of activity and stability for dehydrogenation of LOHCs is a critical challenge. Here, we report the design and synthesis of ultrasmall nickel nanoclusters (∼1.5 nm) deposited on defect-rich boron nitride (BN) nanosheet (Ni/BN) catalysts with higher methanol dehydrogenation activity and selectivity, and greater stability than that of some other transition-metal based catalysts. The interface of the two-dimensional (2D) BN with the metal nanoparticles plays a strong role both in guiding the nucleation and growth of the catalytically active ultrasmall Ni nanoclusters, and further in stabilizing these nanoscale Ni catalysts against poisoning by interactions with the BN substrate. We provide detailed spectroscopy characterizations and density functional theory (DFT) calculations to reveal the origin of the high productivity, high selectivity, and high durability exhibited with the Ni/BN nanocatalyst and elucidate its correlation with nanocluster size and support-nanocluster interactions. This study provides insight into the role that the support material can have both regarding the size control of nanoclusters through immobilization during the nanocluster formation and also during the active catalytic process; this twofold set of insights is significant in advancing the understanding the bottom-up design of high-performance, durable catalytic systems for various catalysis needs.

High-performance light-driven heterogeneous CO2 catalysis with near-unity selectivity on metal phosphides

Akin to single-site homogeneous catalysis, a long sought-after goal is to achieve reaction site precision in heterogeneous catalysis for chemical control over patterns of activity, selectivity and stability. Herein, we report on metal phosphides as a class of material capable of realizing these attributes and unlock their potential in solar-driven CO2 hydrogenation. Selected as an archetype, Ni12P5 affords a structure based upon highly dispersed nickel nanoclusters integrated into a phosphorus lattice that harvest light intensely across the entire solar spectral range. Motivated by its panchromatic absorption and unique linearly bonded nickel-carbonyl-dominated reaction route, Ni12P5 is found to be a photothermal catalyst for the reverse water gas shift reaction, offering a CO production rate of 960 ± 12 mmol gcat−1 h−1, near 100% selectivity and long-term stability. Successful extension of this idea to Co2P analogs implies that metal phosphide materials are poised as a universal platform for high-rate and highly selective photothermal CO2 catalysis.

Fabrication of immobilized nickel nanoclusters decorated by C N species for cellulose conversion to C2,3 oxygenated compounds: Rational design via typical C- and N-sources

Abstract Production of chemicals and fuels from microcrystalline cellulose has inspired scholars’ attention. Deactivation of metallic catalysts including acid leaching and hydrothermal aggregation is still one of the core issues in these systems. To address these problems, we designed and fabricated a series of Ni-W/SiO2 catalysts, which were decorated by CxNy species using C- and N-sources and applied in cellulose conversion to C2,3 oxygenated compounds. The Ni-W/SiO2@CxNy catalysts, underwent complexing and self-assembling process, exhibited special heterojunctions, accompanying strong interactions mainly among Ni phase and CxNy layers. Catalytic results showed that the heterojunctions and outer CxNy layers extensively enhanced productions of hydroxyacetone (HDA) and ethylene glycol (EG) and promoted the hydrothermal stability through prospering in concentration of Lewis pairs from Ni N—N structure and immobilizing the metallic nanoclusters. 48.25% of EG was yielded under 5.0 MPa H2 pressurized 240 °C water for 2.0 h. The Lewis pair further improved the formation of HDA with 20.92% yield. High hydrothermal stability of Ni-W/SiO2@CxNy catalyst was proved according to the recycling results and trace leaching concentration of Ni and W. This construction of metallic catalysts exploited a new strategy to manufacture extraordinary durability of metallic nanoclusters for cellulose conversion under harsh reaction conditions.

CO, NO, and SO adsorption on Ni nanoclusters: a DFT investigation.

Nickel nanoclusters are very promising for catalysis-related applications, especially involving chemical reactions with polluting molecules, such as carbon, nitrogen, and sulfur monoxides, which are directly or indirectly involved in serious environmental pollution problems. Therefore, it is of utmost importance to improve the understanding of the interaction between Ni nanoclusters and diatomic molecules, such as CO, NO, and SO, to provide insights into real subnano catalysts. Thus, here, we report an ab initio investigation based on density functional theory calculations within van der Waals D3 corrections to investigate the adsorption properties of CO, NO, and SO on Ni nanoclusters. From energetic and electronic criteria applied to Nin nanoclusters (n = 2-15), we selected Ni6 (octahedron) and Ni10 (triangular pyramid) nanoclusters as supports. According to our analyses, the molecular adsorption increases the stability of Ni nanoclusters, especially for Ni6 systems. The interaction intensity is larger for SO than for NO and CO in adsorbed systems, and the strong OS-Ni interaction is responsible for the well-known sulfur poisoning on transition-metal systems. The lowest energy adsorption sites are onefold for CO/Ni6, NO/Ni6, and CO/Ni10; twofold for NO/Ni10; and threefold for SO/Ni6 and CO/Ni10, where CO and NO molecules sustain linear and perpendicular geometries, while SO geometry changes to a bent configuration resulting from a sideways adsorption. The equilibrium bond lengths of the molecules expand upon adsorption, from 0.9% (NO/Ni6/10) to 11.3% (SO/Ni6/10), consequently, the internal molecular bond strengths decrease, since there is a reduction in the molecular stretching frequencies. This result occurs most strongly for SO followed by NO and CO systems, which was confirmed by an estimation of the energetic contribution of the distortion after the adsorption process. Thus, the strong S-Ni interaction, given by SO chemisorption on hollow sites with a sideways interaction, implies an energetic decrease and, consequently, a part of the energy gained from the SO-Ni interaction is from the SO and nanocluster distortions. Ultimately, using the energy decomposition analysis (from SAPT0) for XO/Ni6 systems, we improved the understanding of the CO and NO (SO) singlet (doublet) spin multiplicities' interaction with Ni6 nanoclusters.

Atomistic Modeling of Metal Nanocluster Motion Caused by Gas Flow Impact

The work is devoted to supercomputer molecular modeling of gas dynamic spraying of nanoparticles on the substrate. The urgency of this problem is related to the development of production technologies for promising nanocoatings and nanomaterials. The observed increase in the power of modern computer and supercomputer systems makes it possible to use mathematical models based on the first principles in numerical experiments. One of such models is the molecular dynamics method. In this paper, a new results of using of direct molecular simulation for calculating of the acceleration of a nickel nanocluster by a nitrogen flow are presented. The data obtained in the calculations allow to optimize the parameters of the accelerating gas system and predict the speed characteristics of the nanocluster near the substrate surface.

The adsorption and activation of oxygen molecule on nickel clusters doped graphene-based support by DFT

The catalytic activation of O2 on nickel nanoclusters doped upon diff ;erent functionalized graphene substrates (monovacancy as well as one, two and three pyridinic nitrogen decorated) was investigated through the density functional theory calculation. We can observed the adsorption characteristics and the catalytic activation of O2 on catalysts is related to the support effect of diff ;erent functionalized graphene supports. The charge of Ni aotms has a good correlation with the adsorption energy of O2 on Nin clusters with different graphene-based support. The electron mainly transferred from the Ni clusters to the O2, and the graphene-based substrates plays a minor role in the electron transfer process. In addition, the Transition State Scaling are suitable for O2 dissociation reaction, and Transition State Scaling verify the accuracy of the O2 dissociation reaction calculation. Furthermore, in accordance with the energy barrier and the thermodynamic analysis of O2 activation reaction, the Ni3 clusters catalyst anchored single vacancy graphene decorated with three nitrogen atoms may be the most promising catalyst for O2 activation reaction. At the same time, this research will cast insight into activation reaction mechanism of O2 on metal nanoclusters catalysts and lay the foundation for the investigation of metal nanoclusters catalysts for the activation reaction of O2.

In-situ generated highly dispersed nickel nanoclusters confined in MgAl mixed metal oxide platelets for benzoic acid hydrogenation

A new and cost-effective NiMgAl mixed metal oxide (Ni2Mg0.5Al1-MMO) catalyst derived from hierarchical flower-like Ni-Mg-Al layered double hydroxides (NiMgAl-LDHs) was fabricated by a hydrothermal-calcination-reduction method. This catalyst showed excellent catalytic performance in the selective hydrogenation of benzoic acid to cyclohexanecarboxylic acid. Notably, recycling experiments demonstrated that this catalyst could be used at least ten times without significant losses in activity and selectivity under harsh reaction conditions; thus, it presents similar behavior to most of noble metal catalysts. A series of characterizations were performed to investigate the relationship between the structure and the catalytic performance of this catalyst and elucidate the mechanism of its good stability. The results demonstrated that the Ni2Mg0.5Al1-MMO catalyst exhibited highly dispersed nickel species due to the well-defined flower-like structure of NiMgAl-MMO platelets as well as the confined effect of Mg and Al oxide species.

Rapid, one-pot, protein-mediated green synthesis of water-soluble fluorescent nickel nanoclusters for sensitive and selective detection of tartrazine.

In the work, water-soluble bovine serum albumin-protected fluorescent nickel nanoclusters (BSA-NiNCs) are used as fluorescent probes to construct a label-free fluorescence quenching sensor for sensitive and selective detection of tartrazine. The fluorescent BSA-NiNCs are synthesized in one pot using BSA as both the template and reducing agent, and hydrogen peroxide as the additive. The as-prepared NiNCs are characterized by using various analytical techniques like transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV-Vis absorption spectroscopy, circular dichroism spectroscopy, and fluorescence spectroscopy. The synthesized BSA-NiNCs have a quantum yield of ca. 8% by using quinine sulfate as a standard. The sensor for tartrazine detection shows a wide linear range of 0.01-3.5 μM, with a low detection limit of 4 nM. The fluorescence quenching very likely results from the combination of the intermolecular interactions and the secondary inner filter effect between BSA-NiNCs and tartrazine. Then, the proposed sensor is successfully employed for tartrazine detection in drink samples, and the results are comparable with those based on a reference HPLC method.

Исследование нанопорошков металлов методом электронной микроскопии

This article presents the results of experiments on the study of metal nanopowders by the method of ultrahigh resolution scanning electron microscopy and transmission microscopy. Electron microscopy is one of the main methods of studying nanomaterials that allows you to directly see the objects under study. In a scanning electron microscope, secondary, reflected and absorbed electrons are used to obtain the image of the sample surface. The remaining emissions are used as additional sources of information. The results of scanning electron microscopy showed that nickel and iron nanoclusters are close to a spherical shape with an average diameter of 50 and 65 nm, respectively. The results of studies by transmission electron microscopy of NP of nickel and iron are consistent with the results obtained using ultrahigh resolution scanning electron microscopy. In contrast to NP of nickel and iron, the histogram of the size distribution of copper NP has a bimodal distribution. The average particle diameter of the first and second fraction is 23.6 and 81 nm, respectively. The results of scanning and transmission electron microscopy showed that copper nanoclusters have distinct crystallographic faces and edges.

Near-field infrared microscopy of nanometer-sized nickel clusters inside single-walled carbon nanotubes.

Nickel nanoclusters grown inside single-walled carbon nanotubes (SWCNT) were studied by infrared scattering-type scanning near-field optical microscopy (s-SNOM). The metal clusters give high local contrast enhancement in near-field phase maps caused by the excitation of free charge carriers. The experimental results are supported by calculations using the finite dipole model, approximating the clusters with elliptical nanoparticles. Compared to magnetic force microscopy, s-SNOM appears much more sensitive to detect metal clusters inside carbon nanotubes. We estimate that these clusters contain fewer than ≈700 Ni atoms.

ReaxFF molecular dynamics simulation of octadecane destruction in the presence of nickel nanocluster

ReaxFF molecular dynamics simulation of octadecane destruction in the presence of nickel nanocluster

Robust nickel cluster@Mes-HZSM-5 composite nanostructure with enhanced catalytic activity in the DTG reaction

Isoparaffin-rich gasoline plays an essential role in the global energy consumption. In this regard, there have been extensive studies to prepare catalysts for efficient synthesis of isoparaffin-rich gasoline. In this paper, we report a protocol to incorporate Ni nanoclusters (NiNC) into mesoporous Mes-HZSM-5 zeolite for the synthesis of NiNC@Mes-HZ catalysts. The catalysts are prepared via impregnation of Ni6(PET)12 clusters into Mes-HZSM-5 zeolite, followed by annealing at 550 °C in air. The NiNC@Mes-HZ catalysts are characterized by TEM, XRD, H2-TPR, NH3-TPD, ICP-MS, as well as N2-physical adsorption method. The Ni clusters (average diameter: ca. 1.2–2.7 nm) are found to locate at mesoporous area of the zeolite and interact with Brønsted acid sites of the HZSM-5 zeolite, evidenced by the pyridine adsorption Fourier-transform infrared spectrum analysis. The NiNC@Mes-HZ catalysts (Ni cluster loading = 0.11 wt%) exhibit 100% conversion of dimethyl ether (DME) with 66.4C% selectivity towards C5-11. Results show 53.5C% of C5-11 product contains isoparaffin. This is considerably higher than that for Mes-HZSM-5 zeolite (27.5C% isoparaffin selectivity) and xNiNP@Mes-HZ (73.4% DME conversion) catalysts in the DTG process at 350 °C. The higher selectivity of the 0.11NiNC@Mes-HZ catalysts towards isoparaffin production is deemed to associate with the ease of DTG reaction to take place at the interface of the Ni nanoclusters and acidic sites of the zeolite. Further, it is shown that the nickel nanoclusters largely improve the durability of Mes-HZSM-5 zeolite (over 205 h), which is mainly due to the inhibition of carbon deposition production during the DTG process, evidenced by TPO-MS analysis of the used NiNC@Mes-HZ. The Ni nanoclusters in the zeolite show good hydrogenation capacity and cracking performance, enhancing the olefin methylation pathway on the acidic sites of Mes-HZSM-5 and attenuating the aromatic methylation cycle during the DTG reaction.

Encapsulation of Nickel Nanoparticles and Homopoly(Vinylsulfonic Acid) in Mesoporous Carbon CMK-3 as an Acid–Metal Bifunctional Catalyst for Tandem Reductive Amination

Facile and clean transformation for synthesizing secondary arylamines through one-pot reductive amination of aniline has been catalyzed by supported nickel nanocluster and poly(vinylsulfonic acid) into mesoporous carbon CMK-3 (Ni/PVSA/CMK-3) as a bi-functional metal/acid heterogeneous catalyst. Vinylsulfonic acid has been polymerized in CMK-3 pores by an in situ method. The process was run in the presence of NaBH4 at room temperature, in a short reaction time, and without secondary product. Various characterization techniques, including FT-IR, XRD, TG, BET, SEM, TEM, DRS-UV, and AAS were employed to disclose the physical and chemical properties of the catalyst. Reaction results demonstrate that the optimized Ni/PVSA/CMK-3 catalyst shows comparable catalytic performance thanks to the nickel metals and the acidic nature of polymer incorporated in mesoporous channels of CMK-3. Besides being eco-friendly (using water as solvent), the method has several advantages such as simple work-up procedure and moderate to high-yield. This catalyst was easily filtered and reused without noticeable loss of activity after 10 runs.

Nickel nanoclusters as a novel emitter for molecularly imprinted electrochemiluminescence based sensor toward nanomolar detection of creatinine

In this study nickel nanoclusters (NiNCs), was promised as novel and economic electrochemiluminescence (ECL) emitter for highly sensitive and selective determination of creatinine in the presence of molecularly imprinted polymer (MIP). The uniform magnetic graphene oxide (GO-Fe3O4) MIP film was established on the surface of ITO electrode and Ni NCs-embedded in MIP, showed a strong anodic ECL emission using tri-n-propylamine (TPrA) as coreactant. During the ECL process, TPrA was oxidized, and Ni NCs got the energy to generate excited state Ni NCs* for light emission. When the imprinted cavities were occupied by creatinine, the ECL emission of Ni NCs on the MIP-modified electrode surface was efficiently quenched. Under optimal conditions, the proposed sensor demonstrated ultrasensitive and accurate analytical performance toward creatinine detection with a linear range from 5 nM to 1 mM and detection limit of 0.5 nM (S/N = 3). The biosensor showed good specificity for creatinine determination compared to other compounds that having the chemical structure analogue or close to the template creatinine, when the concentration ratio of interference to creatinine was more than 100 times. Furthermore, the biosensor was successfully applied to determination of creatinine in human serum and urine samples with satisfactory results. So, this assay for creatinine detection possesses high sensitivity, good selectivity, excellent reproducibility and stability. We expect the combination of molecular imprinting system with ECL assay in the presence of Ni NCs as a new type of superior luminophore candidate can be developed for design of ultrasensitive sensors, biosensors and other measuring devices.

Nickel Nanocluster Loaded Black Titania for Photocatalytic Reduction of CO2 into Solar Fuels: Computational and Experimental Studies

The conversion of atmospheric carbon dioxide (CO2) into solar fuels by imitation of a natural photosynthesis using only water vapor and sunlight for energy has attracted widespread attention recently. One of the key challenges is to design a photocatalyst that can bind and activate the CO2 molecule with smallest possible activation energy and produce selective solar fuel production. In this contribution, we report a combined experimental and computational studies on Ni nanocluster loaded black TiO2 (Ni@TiO2[Vo]) with built-in dual active sites for selective photocatalytic CO2 conversion. Our findings reveal that, the synergistic effect of deliberately induced unsaturated Ni nanocluster and oxygen vacancies provide (1) energetically stable CO2 binding sites with lowest activation energy (0.08eV), (2) highly reactive sites, (3) fast electron transfer pathway, (4) enhanced light harvesting by lowering the band gap. The Ni@TiO2[Vo] photocatalyst has demonstrated highly selective and enhanced photocatalytic activity of more than 18 times higher solar fuel production than the commercial TiO2 (P-25). An insight to the mechanism of interfacial charge transfer and product formation mechanism are explored. The proposed approach to adsorb and activate CO2 molecule on dual active sites can be applied to design other catalysts for photocatalytic CO2 reduction.