Structure Of Nanocubes Research Articles

Morphology-Sensitive Sulfation Effect on Ceria Catalysts for NH3-SCR

In this work, sulfation effect on NH3-SCR performance over CeO2 with different morphology (nanocubes and nanorods) was carefully studied. A morphology-sensitive sulfation effect on NH3-SCR activity was observed on CeO2. Interestingly, the NO removal efficiencies of CeO2 nanocubes and CeO2 nanorods got greatly enhanced after the sulfation at low-temperature range ( 350 °C). A series of characterizations such as N2 adsorption–desorption, XRD, HR-TEM, TG–DTA, Raman and in situ DRIFTS of SO2 + O2 adsorption were conducted to investigate the interactions between SO2 and nano-shaped CeO2. It was revealed that the morphology of CeO2 nanorods was damaged severely when sulfated at high temperature (> 350 °C), while the structure of CeO2 nanocubes was relatively stable under the same condition. Furthermore, more sulfate species were found on CeO2 nanorods than on CeO2 nanocubes, in particular of bulk like sulfate species. As a result, the NO removal efficiency of CeO2 nanorods declined greatly when sulfated at high temperature.

Glucose-sensing abilities of mixed-metal (Ni Co) Prussian blue analogs hollow nanocubes

Abstract Ni Co Prussian blue analogs (PBA) with a structure of hollow nanocubes (Ni Co PBA HNCs) are successfully prepared by simple static settlement at room temperature and ammonia etching method. The Ni Co PBA HNCs exhibit an enhanced catalytic activity towards glucose oxidation. The three-dimensional Ni Co PBA HNCs modified electrode form a novel glucose sensor which not involved the enzyme. The properties of glucose sensor based on Ni Co PBA HNCs are explored by electrochemical technique, for instance, cyclic voltammetry (CV), differential impulse voltammetry (DPV) and typical amperometric-time method (i-t). As compared to pure Ni PBA HNCs and pure Co PBA HNCs, the Ni Co PBA HNCs exhibit outstanding catalytic performance for electro-oxidation of glucose. The bimetal synergetic catalyst of Ni and Co in the Ni Co PBA HNCs causes this sensor with superior oxidation capacity for glucose. The analysis of the experimental data prove that this glucose sensor based on Ni Co PBA HNCs possesses wide linear range: 0.002 mM – 3.79 mM, low detection limit: 1.2 μM (S/N = 3), high sensitivity: 149 μA·mM−1·cm−2, as well as good selectivity. We further find that the proposed glucose sensors can be successfully applied to detect glucose levels in drinks experiment.

Bimetallic Ni/Co-ZIF-67 derived NiCo2Se4/N-doped porous carbon nanocubes with excellent sodium storage performance

Ni-Co-based zeolitic imidazolate framework (Ni/Co-ZIF-67) derived NiCo2Se4/N-doped porous carbon (NiCo2Se4@NPC) nanocubes are used as anode materials of sodium ion batteries (SIBs). The nano size and porous structure of NiCo2Se4 nanocubes accelerate reaction kinetics and relieve volume expansion, and the porous carbon increases the material’s electronic conductivity. Moreover, the electrochemical process of the NiCo2Se4@NPC electrode materials is mainly dominated by pseudocapacitive behaviors according to the kinetic studies by cyclic voltammetry. Consequently, NiCo2Se4@NPC nanocubes deliver a high discharge capacity of 462.1 mAh g−1 at 0.1 A g−1 after 70 cycles in SIBs. Even at a high current density of 2 A g−1, the discharge capacity of NiCo2Se4@NPC nanocubes can reach 372 mAh g−1. This study provides a reliable basis for the preparation of bimetallic selenide and helps to promote the development of bimetallic selenide as anode in SIBs.

Porous phosphorus-rich CoP3/CoSnO2 hybrid nanocubes for high-performance Zn-air batteries

Porous metal phosphide cubes with exposed vertices and edges containing abundant catalytically active sites are promising electrocatalysts. Herein, by integrating the advantages of the phosphorus-rich cobalt phosphides and bimetallic oxides to form hybrid architectures, we prepared CoP3/CoSnO2 via phosphating CoSn(OH)6 nanocubes, which has unique porous nanocubic structure. The optimized CoP3/CoSnO2 porous nanaocubes showed excellent electrocatalytic activity for OER/ORR. What’s more, the electrochemical performances of CoP3/CoSnO2 porous nanaocubes as air cathode catalyst for zinc air batteries were better than that of commercial RuO2 and 20 wt% Pt/C with a mass ratio of 1:1 as the air cathode catalyst. This work offers a new strategy to fabricate metal phosphide with porous nanocubic structures.

Top-Open Hollow Nanocubes of Ni-Doped Cu Oxides on Ni Foam: Scalable Oxygen Evolution Electrode via Galvanic Displacement and Face-Selective Etching.

Self-standing and cost-effective electrodes for high-performance oxygen evolution reaction (OER) are vital for emerging energy storage and conversion technologies. We report a scalable binder-free OER electrode with open hollow nanocubes of Ni-doped CuOx on Ni foam (hNC/NF) through spontaneous galvanic displacement followed by simple electrochemical oxidation. Face-selective etching for the unique structure of hollow nanocubes with large open ends is achieved by utilizing the different accessibility of the top and side faces of cubes to solution species, more specifically the depletion of reactants between the densely supported nanocubes. Besides, the in situ deposition on Ni foam allows spontaneous Ni doping, which, as revealed by DFT calculations, fortunately strengthens the adsorption of oxygenated intermediates and therefore could optimize the free energy path of OER on Cu oxides. Benefiting further from the high accessible surface area of the unique open hollow architecture, the hNC/NF exhibits an outstanding OER activity with a small overpotential (η = 305 mV at 10 mA cm-2) as well as excellent stability without significant decay after 120 h operation. To our knowledge, this should represent the best OER performance of Cu-based electrocatalysts and is competitive with those based on Fe-group metals. Besides, the hNC/NF-based water electrolyzer delivers a performance of 1.50 V cell voltage at 10 mA cm-2, offering great promise for practical application.

Porous CoP@N/P co-doped carbon/CNTs nanocubes: In-situ autocatalytic synthesis and excellent performance as the anode for lithium-ion batteries

A rational and convenient method was selected to prepare CoP@N/P-co-doped-(C/CNTs) (CoP@N/P-(C/CNTs)) composites with porous nanocubic structure through a pyrolysis-phosphorization strategy derived from ZIF-67. The production of N, P-doped carbon and CNTs formed by in-situ autocatalysis improved the electrical conductivity of the nanocomposite greatly and made the combination of N, P-(C/CNTs) with CoP nanoparticles (NPs) very tightly. The CoP NPs were well encapsulated into the N/P-(C/CNTs) polyhedron. The prepared CoP@N/P-(C/CNTs) had a large specific surface area with 114 m2 g−1 and an average pore diameter of about 10 nm, which were helpful for the efficient diffusion of electrolyte and transfer of ions/electrons. Benefiting from the synergistic effects between highly active CoP NPs and wonderfully conductive N/P-C/CNTs, the CoP@N/P-(C/CNTs) composites exhibited outstanding electrochemical performance. As anodes for lithium-ion batteries (LIBs), the CoP@N/P-(C/CNTs) composites exhibited an excellent initial discharge capacity of 1215 mA h g−1 and reversible capacity of 600 mA h g−1 after 200 cycles at 0.5 A g−1. Even at the high current density of 2 A g−1, it still retained a capacity of 385 mA h g−1. It proved that the autocatalytic formation of CoP@N/P-(C/CNTs) resulted from Co-MOFs is an economical and convenient approach to synthesize electrode materials with high performance for LIBs.

Investigation of electrochemical performance, optical and magnetic properties of NiFe2O4 nanoparticles prepared by a green chemistry method

Green chemistry methods for synthesising metal oxides nanoparticles (NPs) have been extensively used due to their tremendous and remarkable advantages such as easy preparation, reliable results, non toxicity, low cost and eco-friendly. Based on these advantages we have applied a green chemistry method for synthesising Nickel Ferrite (NiFe 2 O 4 ) NPs mediated plant extract from Persa Americano seeds . XRD pattern confirmed the spinel phase structure of the synthesised NiFe 2 O 4 NPs. Fourier Transform Infrared (FTIR) spectroscopy showed the chemical bonds of the sample are consistent with the bonds assigned to NiFe 2 O 4 NPs. Morphological studies revealed the cubic shapes for some of the particles with average sizes range from 15nm to 20nm and irregular shapes for the others. The optical properties were studied using UV–Vis spectrophotometer and the obtained results indicated that NiFe 2 O 4 NPs exhibit a strong absorption behaviour in the UV range with a maximum peak at 250nm. The optical band gap calculated based on UV–Vis result was 4.25 eV. Photoluminescence (PL) spectrum of NiFe 2 O 4 NPs revealed two emission peaks, one in the UV region centred at 379nm and another a broad peak in nearly visible region (Blue emission) centred at 450nm. Magnetic studies showed a decrease in saturation magnetization Ms of NiFe 2 O 4 NPs compared to their bulk system which is attributed to surface spin disorder. Finally, NiFe 2 O 4 NPs exhibited excellent electrochemical properties which can be ascribed to: this compound possess two electrochemical active components and / or the nanocube structure of the particles which can further improve the electrochemistry through the feasible oxidation states and the synergetic effect. • A green chemistry method was successfully used to synthesis NiFe 2 O 4 NPs. • Morphological studies showed nanocubes shape of the particles. • Low value of Ms for NiFe 2 O 4 NPs was observed. • NiFe 2 O 4 NPs exhibited excellent electrochemical performance.

Glucose Analyzer Based on Self-made Biosensor for High-performance Glucose Detection

The concentration analyzer with high precision and wide range is the core device for monitoring the fermentation process. In this work, we designed and proposed a lowcost three-electrode glucose analyzer based on a self-made screen-printed enzyme biosensor chip, which has a Prussian blue (PB) nanocubic structure and leads to high sensitivity of 117.31 μAmM-1cm-2. The hardware design of the glucose analyzer can be divided into five critical parts, including digital, signal treatment system, power supply, motor-driven and the host computer. The signal treatment system is used to collect, convert and amplify the weak current signal generated by the biosensor. The digital circuit of the central processing unit of the analyzer is designed using the STM32F407ZET6. Besides, an external analog-to-digital converter is used to achieve high precision A/D conversion. The stability of the potentiostat is ensured by designing the precision power supply, hardware filtering, and algorithm filtering. The experimental results show that the glucose analyzer has a wide linear detection range from 1g/L to 120g/L and the coefficient of variation at 1g/L is 0.038, which exhibits excellent performance in stability and detection accuracy. The analyzer can be applied in the future for in-situ measurement of glucose concentration for its wide-range and high-precision detection capabilities.

Fe (PB)-P-Se NANOCUBES AS HER ELECTROCATALYSTS FOR OVERALL EFFICIENT WATER-SPLITTING

In recent times, selecting an effective electrocatalyst has attracted a lot of attention for improving the efficiency of water splitting to obtain clean fuels as an energy carrier. In this study, a self-pattern strategy is reported to synthesize Selenide (Se)-Phosphate (P) mixed Prussian blue (PB) cubic nanocubes for the electrocatalytic hydrogen evolution reaction (HER). The as-prepared nanocubes were characterized by different techniques. SEM and TEM confirm that the nanocube structure has been successfully formed. XRD pattern obtained peaks meets with the standard JCPDS no. 01-0239.The resulting P-Se mixed nanocubes worked as a superior HER electrocatalyst, which affords a current density of 10 mA cm−2 at a small overpotential of 210mV; at the overpotential of 211mV; a Tafel slope as 147 mV/dec in 1M KOH; and excellent stability in alkaline medium. From results, we affirmed that Prussian based nanocubes can work with great potential in water splitting.

X (metal: Al, Cu, Sn, Ti)-functionalized tunable 2D-MoS2 nanostructure assembled biosensor arrays for qualitative and quantitative analysis of vital neurological drugs.

In this work we report for the first time surface functionalization of 2D MoS2 with X (metals: Al, Cu, Sn, Ti) to develop a low-cost, ultra-selective biosensor array based Electronic Tongue (E-Tongue) for the detection of 4 vital neurological drugs in human saliva. The hydrothermally grown surface functionalized X-MoS2 was integrated onto a single 1 × 1 cm aluminium foil and contacts were defined using Cr electrodes. Detailed characterization revealed the formation of 2-H MoS2 and metal-X (Al, Cu, Sn, Ti)-functionalized MoS2 nanoflower like morphology decorated with nanoflake, nanorod, nanocube and nanostick structures, respectively. The response of the sensor array was recorded for aspirin, nicotine, caffeine and tramadol. Principal Component Analysis (PCA) was performed to reduce the dimension of numerous response data sets from all sensors and predict the likely possible response from various neurological drugs towards each sensor. Pattern-recognition analysis confirmed a definite pattern in response to respective functionalization and could efficiently differentiate neurological drugs from one another. Real-time analysis was performed using saliva samples for monitoring the therapeutic neurological drug concentration in the human body. Furthermore, the biosensor array was exposed to respective neurological drugs to study their sensitivity, selectivity, stability, reproducibility and adhesion onto the device. The strategy outlined can be used to develop lab-on-a-chip devices for the real-time detection of numerous bioanalytes in body fluids.

Formaldehyde sensing characteristics of hydrothermally synthesized Zn2SnO4 nanocubes

Metal oxide semiconductor-based gas sensor preferentially possessing great attention due to its outstanding gas sensing performances. Nevertheless, monobasic oxides could not tackle problems such as high operating temperature, poor selectivity and durability. Here, a facile and cost-efficient hydrothermal method has been exploited to produce Zn2SnO4 nanocube as a multi-oxide semiconductor formaldehyde gas sensor. The fabricated gas sensorexhibited remarkable response value (Rair/Rgas = 23.57) and response/recovery time (15/17 s) to 50 ppm formaldehyde at the optimal operating temperature of 230 °C, respectively. The excellent gas sensing mechanism of sensor is carefully discussed which can be attributed to large specific surface area (24.83 m2/g), distinct nanocube structure and high pore size (83.19 nm).

Modulating the Electronic Structure of Porous Nanocubes Derived from Trimetallic Metal-Organic Frameworks to Boost Oxygen Evolution Reaction Performance.

The preparation of noble metal-free catalysts for water splitting is the key to low-cost, sustainable hydrogen generation. Herein, through a pyrolysis-oxidation process, we prepared a series of Co-Fe-Ni trimetallic oxidized carbon nanocubes (Co1-X FeX Ni-OCNC) with a continuously changeable Co/Fe ratio (X=0, 0.1, 0.2, 0.5, 0.8, 0.9, 1). The Co1-X FeX Ni-OCNC shows a volcano-type oxygen evolution reaction (OER) activity. The optimized Co0.1 Fe0.9 Ni-OCNC achieves a low overpotential of 268 mV at 10 mA cm-2 with a very low Tafel slope of 48 mV dec-1 in 1 m KOH. At the same time, the stability of the Co0.1 Fe0.9 Ni-OCNC is also outstanding; after 1000 CV cycles, the LSV plot is almost coincident. Moreover, the potential remains almost of the same value at 10 mA cm-2 after 12 h in comparison to the initial value. The excellent electrocatalytic properties can be attributed to the synergistic cooperation between each component. Therefore, the Co0.1 Fe0.9 Ni-OCNC is a promising candidate instead of precious metal-based electrocatalysts for OER.

Activated carbon doped WO3 for photocatalytic degradation of rhodamine-B

In this research work, tungsten trioxide (WO3) and activated doped WO3 composites were prepared for the photocatalytic degradation of rhodamine-B. Activated carbon was prepared by waste sugarcane burgesses, tungsten trioxide (WO3) was synthesized by precursor sodium tungstate dihydrate (Na2WO4·2H2O) using hydrothermal method. To study the morphology, functional groups, band gap, purity and optical properties of the prepared catalyst SEM, FTIR, PL and UV–Vis spectroscopy were used. SEM micrograph shows that tungsten trioxide has nanocubic rods-like structure with size 50–500 nm. Morphological results showed that nano rods become sharper when activated carbon were added in WO3. The average nanorods have average size 20–250 nm which is very efficient for degradation. UV–Vis spectroscopy shows that band gap of the fabricated catalyst changes from 2.76 to 2.26 eV by varying the concentration ratio of the activated carbon. FTIR analysis the functional groups of the prepared catalyst. PL-spectroscopy determined that the maximum excitation wavelength was 446 nm. Photocatalytic results show that 2% activated carbon doped WO3 composite shows the maximum degradation rate as compare to the other prepared catalyst. Synthesized catalysts are environment friendly, cost effective and due to low band gap very useful for the degradation purpose.

Replacing PVP by macrocycle cucurbit[6]uril to cap sub-5 nm Pd nanocubes as highly active and durable catalyst for ethanol electrooxidation

Pd nanocubes (NCs) enclosed by six {100} facets are fascinating model materials for both fundamental studies and practical applications. However, the only available method to prepare well-defined sub-10 nm Pd NCs was developed by Xia et al. more than 10 years ago, unavoidably using polyvinylpyrrolidone (PVP) polymer to prevent particle aggregation. The strongly adsorbed PVP extremely deteriorates the catalysts’ efficiency because of the high coverage of accessible surface-active sites. Numerous efforts have been devoted to replacing PVP with weaker capping agents but with limited progress predominately due to the difficulties in tuning the growth kinetics of Pd NCs. For the first time, we report that macrocycle cucurbit[6]uril (CB[6]) can replace PVP in the synthesis of Pd NCs by dedicatedly controlling the growth parameters. CB[6] capped Pd NCs showed 1.1–1.5 times increased specific surface area compared to the surfactant-free commercial Pd catalysts. Moreover, X-ray photoelectron spectroscopy demonstrated the modified electronic structure of Pd NCs through the carbonyl group of CB[6]. Consequently, compared to the commercial catalysts, the obtained Pd NCs exhibited 7 times higher current density towards ethanol oxidation reaction. Remarkably, after 17 h of continuous work, it reduced deactivation by up to 1–4 orders of magnitude.

Synthesis of oxygen-deficient and monodispersed Pr doped CeO2 nanocubes with enhanced resistive switching properties

Monodispersed praseodymium (Pr) doped cerium oxide (CeO2) nanocubes (∼ 10 nm) were successfully synthesized via a facile two-phase solvothermal method and further assembled into a dense film through a drop-coating procedure for resistive switching applications. The XRD and Raman results showed that Pr element was successfully doped into the CeO2 lattice structure while maintaining the highly uniform nano-cubic structure. In addition, the concentration of oxygen vacancy in CeO2 nanocubes could be effectively modulated by varying dopant concentration evidenced by XPS and Raman analysis. The two-terminal structured device of Au/Pr doped CeO2/fluorine-doped tin oxide (FTO) exhibits stable resistive switching behaviour and ON/OFF endurance for more than 1000 cycles at a small operational voltage ranging from -0.6 to 1V. The present study may extend the potential of using praseodymium (Pr) doped cerium oxide nanocube in nanoscale building block for novelty 3D architectural memory and logic design in data-dependent applications such as artificial intelligence (AI) system and machine learning.

Wide range refractive index sensor based on a coupled structure of Au nanocubes and Au film

We report a plasmonic refractive index sensor with a wide measurement range based on periodic gold nanocubes coupled with a gold film. The theoretical sensing range is 1.0–1.8. The structure consists of two-dimensional gratings composed of periodic nanocubes that both excite local surface plasmon resonance and stimulate propagating surface plasmon resonance. The strong resonance of the multiple surface plasmons is suitable for use in refractive index sensing and effectively reduces the full width at half maximum of the resonance peak. The sensing performance of each resonant mode in the reflected spectrum is discussed in detail. The highest sensitivity and figure of merit of the proposed sensor are 1002 nm per refractive index units (RIU) and 417 RIU−1, respectively. The proposed sensor will be useful for bio-chemical sensing applications such as measuring changes in the refractive index of gases or liquids.

Hollow copper sulfide nanocubes as multifunctional nanozymes for colorimetric detection of dopamine and electrochemical detection of glucose

Nanozymes have fascinated increasing attention in the field of artificial enzyme. Designing an ideal nanozyme usually requires a synergic advantage of reasonable nanostructures and large specific surface area for ensuring excellent mimicking-enzyme catalytic activity. Here we report a CuS nanozyme with hollow nanocube structure (h-CuS NCs), which has a large surface area of 57.84 m2 g−1, and thus realizes excellent mimicking-enzyme catalytic activity. Expectedly, our directed design of h-CuS NCs nanozymes has an affinity for H2O2 of 0.94 mM, which is outstanding among the state-of-the-art Cu-based nanozymes. Furthermore, this nanozyme acts as a multifunctional catalyst to induce luminol chemiluminescence and oxide 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the presence of H2O2, and displays distinguished electrocatalytic activity to glucose oxidation. More intriguingly, the nanozyme can produce a promising photothermal effect under the illumination of near-infrared light. This work will provide a prototype for rational design of distinct nanostructures as multifunctional nanozymes in the area of electrochemical sensing, mimicking-enzyme catalytic biosening and cancer therapy.

Molecular Dynamics Study on Dynamical Features of Reorganization Process for Nanocapsule Formed with Gear-Shaped Amphiphile Molecules.

We have analyzed the dynamical feature of a hexameric structure of nanocube (16) from a gear-shaped amphiphile molecule (1) upon addition of solvophobic spherical adamantane molecule (G), by means of molecular dynamics (MD) simulation, to elucidate the conversion mechanism from the hexameric nanocube G@16 to a tetrameric G@14 tetrahedron. The adamantane molecule (G) in the nanocube G@16 is located around the triple π stacking, although G in the G@14 tetrahedron is at the central position of the capsule. Our MD simulation shows that the nanocube G@16 is more fluctuated than the G@14 tetrahedron. We have also found that a demethylated nanocube G@26 is converted to a tetrameric G@23 tetrahedron due to the solvophobic effect for the adamantane molecule.

Surface-enhanced Raman scattering by composite structure of gold nanocube-PMMA-gold film

In this study, we experimentally prepared composite structures of 170 nm gold nanocube, poly(methyl methacrylate) (PMMA) spacer layers with different thicknesses, and 50 nm gold film as substrates for surface plasmons excitation and surface-enhanced Raman scattering (SERS). The SERS spectra of gold nanocube and the composite structure were studied by using a 633 nm laser as an excitation source and rhodamine 6G (R6G) as the Raman probe molecule with 5.625 µg/mL gold nanocube aqueous solution. It was found that the composite structures produced much stronger SERS signals than that with the single gold nanocube structure. The relationship between the intensities of SERS Raman peaks and the PMMA spacer layer thicknessess of the composite structures was found to have the same trend as that between the Raman enhancement factor and PMMA spacer layer thickness obtained by the finite element method simulation. Furthermore, a R6G concentration as low as 10−12 M could be detected by the composite structure.

Facile synthesis of bimetallic Pt-Pd symmetry-broken concave nanocubes and their enhanced activity toward oxygen reduction reaction

In the present work, we are reporting a facile one-pot synthesis route to get Pt-Pd symmetry-broken concave nanocube (SBCNCs) structures in N, N-dimethylformamide (DMF) solutions under the effect of iodide ions and Poly (vinylpyrrolidone) (PVP). By given the inhibiting effect of non-stirring during the reaction process, and the capping agent effect, newly formed atoms is expected to accumulate at the vertexes and/or the edges of nanocube, leading to the formation the Pt-Pd SBCNCs. These structures are in a thorough manner physicochemically and electrochemically characterized.It is found that the specific structure of Pt-Pd SBCNCs is composed of various high-index facets and Pt-rich surface. These features enable a superior performance for the oxygen reduction reaction, and the specific/mass activities of the Pt-Pd SBCNCs are 7.7/6.2 times higher than commercial TKK-Pt/C, respectively. It also exhibits a remarkable durability by only reduced 30 mV half-wave potential after 15,000 accelerated durability test (ADT) cycles. This work provides an effective and simple strategy to rationally design electrocatalysts with enhanced activity and durability toward oxygen reduction reaction or other practical applications.