Oxide Nanocubes Research Articles

Synthesis of Carbon Quantum Dots Combined with Cu2O Nanocubes and Their Application in Metals Ion Detection.

In this study, carbon quantum dots/Cu2O nanocubes (CQDs/Cu2O NCBs) nanomaterial has been successfully synthesized using a simple and easy-to-implement method with a quick reaction time (90 min) at 80°C. In particular, carbon quantum dots (CQDs) were obtained by green and environmentally friendly synthesis methods, using abundant and naturally available raw materials from rice flour and applying hydrothermal approach. Besides, cuprous oxide nanocubes (Cu2O NCBs) were also synthesized through non-toxic compounds. The morphology and composition of CQDs/Cu2O NCBs and Cu2O NCBs were analyzed through UV-vis, FTIR, XRD, FE-SEM, TEM, and EDX spectroscopy. The results showed that Cu2O NCBs have a cubic shape with an average particle size of ~ 29-31 nm, and CQDs have spherical shape with a size of ~ 4-8 nm. In addition, CQDs/Cu2O NCBs nanomaterial was also employed as a "turn-on" fluorescence sensor" for application in metal ions detection. The obtained results showed that the CQDs/Cu2O NCBs are potential and promising in detecting Pb2+ ions in the wide range from 1.8M to 10- 9 M and extremely low limit of detection of 27.8 nM at the excitation wavelength of 340nm. CQDs/Cu2O NCBs-based sensors are highly sensitive and selective for Pb2+ detection. Therefore, CQDs/Cu2O are promising as photocatalytic materials for various applications, including sensors, bio-probes biomedical, optoelectronics, etc.

Rational design of cobalt oxide nanocubes arrays on Ni foam as durable and robust electrocatalyst for urea electro-oxidation

BackgroundCobalt oxide (Co3O4) is a promising electrocatalyst for efficient urea electro-oxidation, tackling power consumption and environmental challenges. The controllable design of free-standing Co3O4 nanostructures grown on Ni foam (NF) substrates was achieved using a green and facile hydrothermal approach. Different reducing agents were applied to synthesize various morphological structures of Co3O4, including nanoparticles, nanowires, and nanocubes (NCs) morphologies.ResultsThe as-fabricated electrodes were investigated as electrocatalysts for enhanced urea electro-oxidation. Because of its 3D nanostructure with minimal agglomeration and a large interfacial surface area with adequate electroactive sites, the Co3O4 NCs/NF had the best energy conversion efficiency of any electrode toward the urea oxidation process. These distinctive features facilitated the electron and urea routes used in the urea electro-oxidation process. It had a low-onset potential of 194.2 mV (vs. Hg/HgO) and a current density of 90.2 mA cm−2 in a 1 M KOH electrolyte. The electrocatalyst demonstrated excellent anodic activity for urea electro-oxidation with an onset potential of 196.7 mV and a current density of 256.1 mA cm−2 in 1 M KOH + 0.3 M urea concentration. Furthermore, the Co3O4 NCs/NF exhibited long-term stability, as shown by chronoamperometry and stepwise tests after 3600 s in the presence of urea under various operating conditions.ConclusionsCompared to all the fabricated Co3O4 nanostructures, the Co3O4 nanocubes revealed the highest electrocatalytic performance toward urea electro-oxidation in all concentrations. Therefore, Co3O4 NCs/NF is a promising, robust, and efficient electrocatalyst for direct urea fuel cell applications.

Shape‐Control in Microwave‐Assisted Synthesis: A Fast Route to Size‐Tunable Iron Oxide Nanocubes with Benchmark Magnetic Heat Losses

AbstractIron oxide nanocubes (IONCs) are among the most promising materials in magnetic hyperthermia (MHT) for tumor therapy as they can efficiently convert magnetic energy into heat under alternating magnetic field (AMF). Conventional IONCs syntheses are based on thermal decomposition methods, limited by the long reaction time (hours) and milligram‐scale production; while, solvothermal methods produce gram‐scale amount of high quality IONCs, but, reaction times are of the orders of hours. In this work, a microwave‐assisted route to shape‐control IONCs in which the reaction time is reduced to minutes while achieving a high iron conversion yield up to 80% is reported. The size of the IONCs (range 13–30 nm) is coarse‐tuned by adjusting the amount of benzaldehyde ligand, while fine‐size tuning is achieved by changing temperature and minute‐reaction time. IONCs exhibit superparamagnetic behavior at 298 K with saturation magnetization over 80 emu gIONC−1 and possess high specific absorption rate values (SAR) up to 400 W gFe−1 at clinical AMF conditions. These results mark a milestone for rapid synthesis of IONCs at high yield conversion of well‐defined size and shape nanocubes with benchmark MHT heat performance while using a fast route, with limited energy consumption which makes this method greener and cheaper than previous ones.

Recycling the Spent Lithium-ion Battery into Nanocubes Cobalt Oxide Supercapacitor Electrode

Background:: Cobalt oxide nanocubes have garnered significant attention as potential supercapacitor electrodes due to their unique structural and electrochemical properties. The spent lithium-ion batteries (LiBs) are considered as zero-cost source for cobalt oxide production. Objective:: The aim of this work is to recover cobalt oxide from spent LiBs and study its electrochemical performance as a supercapacitor electrode material. Method:: This study uses an electrodeposition method to obtain cobalt oxide honeycomb-like anodes coated on Ni foam substrates from spent Li-ion batteries for supercapacitors applications. The effect of annealing temperature on the cobalt oxide anode has been carefully investigated; 450 ºC annealing temperature results in nanocubes on the surface of the cobalt oxide electrode. X-ray diffraction confirmed the formation of the Co3O4-NiO electrode. Results:: The Co3O4-NiO nanocubes electrode has shown a high specific capacitance of 1400 F g-1 at 1 A g-1 and high capacitance retention of ~96 % after 2250 cycles at a constant current density of 10 A g-1 compared to 900 F g-1 at 1 A g-1 as for prepared Co3O4 honeycomb. Conclusion:: This strategy proves that the paramount importance of Co3O4-NiO nanocubes, meticulously synthesized at elevated temperatures, as a supremely effective active material upon deposition onto transition metal foam current collectors, establishing their indispensability for supercapacitor applications.

Nanoplatforms for Magnetic-Photo-Heating of Thermo-Resistant Tumor Cells: Singular Synergic Therapeutic Effects at Mild Temperature.

A self-assemble amphiphilic diblock copolymer that can incorporate iron oxide nanocubes (IONCs) in chain-like assemblies as heat mediators for magnetic hyperthermia (MHT) and tuneable amounts of IR780 dye as agent for photothermal therapy (PTT) is developed. MHT-heating performance of photobeads in viscous media have the same heat performances in water at magnetic field conditions of clinical use. Thanks to IR780, the photobeads are activated by infrared laser light within the first biological window (808nm) with a significant enhancement of photo-stability of IR780 enabling the raise of the temperature at therapeutic values during multiple PTT cycles and showing unchanged optical features up to 8 days. Moreover, the photobeads fluorescent signal is preserved once internalized by glioblastoma multiforme (GBM) cells. Peculiarly, the photobeads are used as toxic agents to eradicate thermo-resistant GBM cells at mild heat, as low as 41°C, with MHT and PTT both of clinical use. Indeed, a high U87 GBM cell mortality percentage is obtained only with dual MHT/PTT while each single treatment dose not provide the same cytotoxic effects. Only for the combined treatment, the cell death mechanism is assigned to clear sign of apoptosis as observed by structural/morphological cell studies and enhanced lysosome permeability.

Scalable bilayer thin coatings with enhanced thermal dissipation for passive daytime radiative cooling

Passive daytime radiative cooling (PDRC) is a ground-breaking strategy to realize subambient cooling without any extra energy and environmental pollution. However, the challenge is how to work out the contradiction between thick films (typically 300–800 μm) for efficient cooling and thin films for practicality. Herein, we propose a scalable bilayer thin PDRC coating consisting of waterborne polyurethane / hollow glass beads top layer and poly(vinylidene fluoride-co-hexafluoropropene) / zinc oxide nanocubes underlayer, exhibiting sufficient solar reflectance (0.92), longwave infrared emissivity (0.93) and a relatively high thermal conductivity (1.702 W m−1 K−1) with a thin thickness of 100 μm. Real-time temperature detection demonstrated a subambient cooling of 8.1 °C and an above-ambient cooling of 18.1 °C compared with traditional coating under intense solar irradiation (∼883 W m−2). Such thin PDRC coatings with enhanced thermal dissipation can bring vast opportunities for sustainable applications, and offer an alternative pathway toward achieving effective thermal management.

Tailoring the Magnetic and Hyperthermic Properties of Biphase Iron Oxide Nanocubes through Post-Annealing

Tailoring the magnetic properties of iron oxide nanosystems is essential to expanding their biomedical applications. In this study, 34 nm iron oxide nanocubes with two phases consisting of Fe3O4 and α-Fe2O3 were annealed for 2 h in the presence of O2, N2, He, and Ar to tune the respective phase volume fractions and control their magnetic properties. X-ray diffraction and magnetic measurements were carried out post-treatment to evaluate changes in the treated samples compared to the as-prepared samples, showing an enhancement of the α-Fe2O3 phase in the samples annealed with O2 while the others indicated a Fe3O4 enhancement. Furthermore, the latter samples indicated enhancements in crystallinity and saturation magnetization, while coercivity enhancements were the most significant in samples annealed with O2, resulting in the highest specific absorption rates (of up to 1000 W/g) in all the applied fields of 800, 600, and 400 Oe in agar during magnetic hyperthermia measurements. The general enhancement of the specific absorption rate post-annealing underscores the importance of the annealing atmosphere in the enhancement of the magnetic and structural properties of nanostructures.

Detection of Cr(III) and Cr(VI) in lake water by inhibiting and enhancing oxidase-like activity of iron-manganese bimetallic oxide nano-cubes

In recent years, most of the researches on nanozymes have focused on improving their catalytic activity and direct synthesis, but this task is still very complicated. Bimetallic oxides are particularly popular because of their mixed valence and special structure. In this study, iron-manganese bimetallic oxide nano-cubes (IMBO NCs) were prepared by a rapid and effective solvothermal synthesis technique, and showed excellent oxidase-like activity. The exposure of Cr(III) and Cr(VI) inhibited and enhanced the catalytic activity of IMBO NCs respectively. On this basis, a simple, economical and accurate colorimetric sensor was established by combining with 3,3′,5,5′-tetramethylbenzidine (TMB). Using oxidase activity instead of traditional peroxidase activity to detect Cr(III) and Cr(VI) greatly shortens the detection time. The method has also been successfully applied to the quantitative monitoring of Cr(III) and Cr(VI) in lake water. This study provides theoretical support for the effective design of bimetallic oxide nanozyme activity and can guide the development of accurate detection systems for the analysis of Cr(III) in food and Cr(VI) in environment.

Singular and Nonsingular Transitions in the Infrared Plasmons of Nearly Touching Nanocube Dimers.

Narrow gaps between plasmon-supporting materials can confine infrared electromagnetic energy at the nanoscale, thus enabling applications in areas such as optical sensing. However, in nanoparticle dimers, the nature of the transition between touching (zero gap) and nearly nontouching (nonzero gap ≲15 nm) regimes is still a subject of debate. Here, we observe both singular and nonsingular transitions in infrared plasmons confined to dimers of fluorine-doped indium oxide nanocubes when moving from touching to nontouching configurations depending on the dimensionality of the contact region. Through spatially resolved electron energy-loss spectroscopy, we find a continuous spectral evolution of the lowest-order plasmon mode across the transition for finite touching areas, in excellent agreement with the simulations. This behavior challenges the widely accepted idea that a singular transition always emerges in the near-touching regime of plasmonic particle dimers. The apparent contradiction is resolved by theoretically examining different types of gap morphologies, revealing that the presence of a finite touching area renders the transition nonsingular, while one-dimensional and point-like contacts produce a singular behavior in which the lowest-order dipolar mode in the touching configuration, characterized by a net induced charge in each of the particles, becomes unphysical as soon as they are separated. Our results provide valuable insights into the nature of dimer plasmons in highly doped semiconductors.

Electrochemiluminescence quenching effect of Cu2O towards flower-like ferric ion-doped g-C3N4 and its application for Cyfra21-1 immunosensing

In this article, ferric ion-doped floral graphite carbon nitride (Fe–CN-3, energy donor) was used to construct the substrate of the immunosensor and copper oxide nanocubes (Cu2O, energy acceptor) were taken as an efficient ECL quenching probe. A sandwich quench electrochemiluminescence (ECL) immunosensor for soluble cytokeratin 19 fragment (Cyfra21-1) detection was preliminarily developed based on a novel resonant energy transfer donor-acceptor pair. Fe–CN-3, a carbon nitride that combines the advantages of metal ion doping as well as morphology modulation, is used in ECL luminophores to provide more excellent ECL performance, which makes a significant contribution to the application and development of carbon nitride in the field of ECL biosensors. The regular shape, high specific surface area and excellent biocompatibility of the quencher Cu2O nanocubes facilitate the labeling of secondary antibodies and the construction of sensors. Meanwhile, as an energy acceptor, the UV absorption spectrum of Cu2O can overlap efficiently with the energy donor's ECL emission spectrum, making it prone to the occurrence of ECL-RET and thus obtaining an excellent quenching effect. These merits of the donor-acceptor pair enable the sensor to have a wide detection range of 0.00005–100 ng/mL and a low detection limit of 17.4 fg/mL (S/N = 3), which provides a new approach and theoretical basis for the clinical detection of lung cancer.

A Non‐Enzymatic Electrochemical Sensor Based on Cerium Oxide Nanocubes for the Rapid Detection of Hydrogen Peroxide Residues in Food Samples†

The rapid and simple detection methods of hydrogen peroxide (H2O2) residues is highly required for food safety. Herein, an electrochemical H2O2 sensor is developed with cerium oxide nanocubes as highly active non‐enzymatic catalyst. Combined with carbon black to improve conductivity, the disposable sensor can determine H2O2 in the range from 100 to 100 μM with a limit of detection (LOD) of 100 nM. This sensor also shows good selectivity and reproducibility, which is enabled to detect H2O2 in real food samples without any pretreatment in 100 s, providing a new solution for the direct quantitative measurement of H2O2 residues for food safety. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Decorating Pd-Au Nanodots Around Porous In2O3 Nanocubes for Tolerant H2 Sensing Against Switching Response and H2S Poisoning.

With the recently-booming hydrogen (H2) economy by green H2 as the energy carriers and the newly-emerged exhaled diagnosis by human organ-metabolized H2 as a biomarker, H2 sensing is simultaneously required with fast response, low detection limit, and tolerant stability against humidity, switching, and poisoning. Here, reliable H2 sensinghas been developed by utilizing indium oxide nanocubes decorated with palladium and gold nanodots (Pd-Au NDs/In2O3 NCBs), which have been synthesized by combined hydrothermal reaction, annealing, and chemical bath deposition. As-prepared Pd-Au NDs/In2O3 NCBs are observed with surface-enriched NDs and nanopores. Beneficially, Pd-Au NDs/In2O3 NCBs show 300 ppb-low detection limit, 5 s-fast response to 500ppm H2, 75%RH-high humidity tolerance, and 56 days-long stability at 280°C. Further, Pd-Au NDs/In2O3 NCBs show excellent stability against switching sensing response, and are tolerant to H2S poisoning even being exposed to 10ppm H2S at 280°C. Such excellent H2 sensing may be attributed to the synergistic effect of the boosted Pd-Au NDs' spillover effect and interfacial electron transfer, increased adsorption sites over the porous NCBs' surface, and utilized Pd NDs' affinity with H2 and H2S. Practically, Pd-Au NDs/In2O3 NCBs are integrated into the H2 sensing device, which can reliably communicate with a smartphone.

Protease-Mediated T1 Contrast Enhancement of Multilayered Magneto-Gadolinium Nanostructures for Imaging and Magnetic Hyperthermia.

In this work, we constructed a multifunctional composite nanostructure for combined magnetic hyperthermia therapy and magnetic resonance imaging based on T1 and T2 signals. First, iron oxide nanocubes with a benchmark heating efficiency for magnetic hyperthermia were assembled within an amphiphilic polymer to form magnetic nanobeads. Next, poly(acrylic acid)-coated inorganic sodium gadolinium fluoride nanoparticles were electrostatically loaded onto the magnetic nanobead surface via a layer-by-layer approach by employing a positively charged enzymatic-cleavable biopolymer. The positive-negative multilayering process was validated through the changes occurring in surface ζ-potential values and structural characterization by transmission electron microscopy (TEM) imaging. These nanostructures exhibit an efficient heating profile, in terms of the specific absorption rates under clinically accepted magnetic field conditions. The addition of protease enzyme mediates the degradation of the surface layers of the nanostructures with the detachment of gadolinium nanoparticles from the magnetic beads and exposure to the aqueous environment. Such a process is associated with changes in the T1 relaxation time and contrast and a parallel decrease in the T2 signal. These structures are also nontoxic when tested on glioblastoma tumor cells up to a maximum gadolinium dose of 125 μg mL-1, which also corresponds to a iron dose of 52 μg mL-1. Nontoxic nanostructures with such enzyme-triggered release mechanisms and T1 signal enhancement are desirable for tracking tumor microenvironment release with remote T1-guidance and magnetic hyperthermia therapy actuation to be done at the diseased site upon verification of magnetic resonance imaging (MRI)-guided release.

Chemical and morphological stability study of copper oxide nanocubes in controlled and non-controlled atmospheres

Chemical and morphological stability study of copper oxide nanocubes in controlled and non-controlled atmospheres

Synthesis of iron oxide nanocubes and their incorporation with luminescent lanthanide (Ln = Tb/ Eu)-Terephthalate complex in silica nanospheres using a reverse microemulsion method

Luminescent magnetic nanocomposites are of interest because of their promising applications in the biomedical field. This article reports the preparation of silica-coated lanthanide terephthalate complexes, Ln-TA (Ln = Tb and Eu) containing luminescent magnetic nanocomposites. Cubic-shaped iron oxide nanoparticles were synthesized through the thermal decomposition of the iron-oleate complex. Then, polymerization of tetraethyl ortho silicate in a water-in-oil reverse microemulsion in the presence of previously prepared iron oxide nanocubes and a terbium (Tb3+)/europium (Eu3+)-terephthalate (TA) complex was performed to obtain luminescent magnetic Fe3O4@Ln-TA (Ln = Tb, Eu)/SiO2 nanocomposites. The size (8.9 nm) and cubic shape of magnetic core were determined via transmission electron microscopy and the superparamagnetic behavior using a vibrating sample magnetometer. Energy dispersive X-ray analysis and inductively coupled plasma optical emission spectroscopy found that the luminescent Tb-TA and Eu-TA complexes were incorporated in the magnetic silica nanocomposites. The nanocomposites, Fe3O4@Ln-TA/SiO2, exhibited distinct luminescent green and red emission peaks and showed promise as a T1 contrast agent for magnetic resonance imaging.

Selective synthesis of copper oxide nanocube for the electrochemical sensing of environmental aquatic pollutant hydroxylamine

Selective synthesis of copper oxide nanocube for the electrochemical sensing of environmental aquatic pollutant hydroxylamine

Enhanced electrochemical reactions at hierarchical nanoporous indium tin oxide based on self-assembly of nanocubes

The enhanced catalytic activity of the nanoporous electrodes with small and uniform pores is caused by structural effects and represents a significant breakthrough in catalysis research. Herein, a new strategy for fabricating hierarchical nanoporous electrodes is presented. Nanoporous electrodes were constructed by self-assembly using indium tin oxide (ITO) nanocube as building blocks. The self-assembly of nanocubes created small and uniform pores between edges, and random aggregation of the small self-assembled clusters readily created a multimodal structure. It was observed that the simple one electron-transfer reaction of Fe ions was greatly improved at the ITO nanoporous electrodes when compared with the flat ITO electrode. Such enhancement is a result of improved reactivity through small pores and rapid mass transfer through large pores. Furthermore, it was confirmed that the catalytic activity of the ascorbic acid reaction increased when using these nanoporous electrodes. These findings provide insight into the fabrication of nanoporous electrodes and their potential use as catalysts.

Integration of Cobalt Phthalocyanine, Acetylene Black and Cu2 O Nanocubes for Efficient Electroreduction of CO2 to C2 H4.

Suppressing side reactions and simultaneously enriching key intermediates during CO2 reduction reaction (CO2 RR) has been a challenge. Here, we propose a tandem catalyst (Cu2 O NCs-C-Copc) consisting of acetylene black, cobalt phthalocyanine (Copc) and cuprous oxide nanocubes (Cu2 O NCs) for efficient CO2 -to-ethylene conversion. Density-functional theory (DFT) calculation combined with experimental verification demonstrated that Copc can provide abundant CO to nearby copper sites while acetylene black successfully reduces the formation energies of key intermediates, leading to enhanced C2 H4 selectivity. X-ray photoelectron spectroscopy (XPS) and potentiostatic tests indicated that the catalytic stability of Cu2 O NCs-C-Copc was significantly enhanced compared with Cu2 O NCs. Finally, the industrial application prospect of the catalyst was evaluated using gas diffusion electrolyzers. The of Cu2 O NCs-C-Copc can reach to 58.4 % at -1.1 V vs. RHE in 0.1 M KHCO3 and 70.3 % at -0.76 V vs. RHE in 1.0 M KOH. This study sheds new light on the design and development of highly efficient CO2 RR tandem catalytic systems.

Iron Oxide Nanocubes as a New Certified Reference Material for Nanoparticle Size Measurements.

The rational design and increasing industrial use of nanomaterials require a reliable characterization of their physicochemical key properties like size, size distribution, shape, and surface chemistry. This calls for nanoscale reference materials (nanoRMs) for the validation and standardization of commonly used characterization methods closely matching real-world nonspherical nano-objects. This encouraged us to develop a nonspherical nanoRM of very small size consisting of 8 nm iron oxide nanocubes (BAM-N012) to complement spherical gold, silica, and polymer nanoRMs. In the following, the development and production of this nanoRM are highlighted including the characterization by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) as complementary methods for size and shape parameters, homogeneity and stability studies, and calculation of a complete uncertainty budget of the size features. The determination of the nanocubes' edge length by TEM and SAXS allows a method comparison. In addition, SAXS measurements can also provide the mean particle number density and the mass concentration. The certified size parameters, area equivalent circular diameter and square edge length, determined by TEM with a relative expanded uncertainty below 9%, are metrologically traceable to a natural constant for length, the very precisely known (111) lattice spacing of silicon. Cubic BAM-N012 qualifies as a certified nanoRM for estimating the precision and trueness, validation, and quality assurance of particle size and shape measurements with electron microscopy and SAXS as well as other sizing methods suitable for nanomaterials. The production of this new iron oxide nanocube RM presents an important achievement for the nanomaterial community, nanomaterial manufacturers, and regulators.

New luminescent hydrophilic iridium(III) nanoflower at low potential for electrochemiluminescence immunosensing

Screening effective luminophore is always one of the most essential concerns in highly sensitive electrochemiluminescence (ECL) bioanalysis. Here, a new nanoflower-like iridium(III) J-aggregate (T-Ir) was prepared via nonionic surfactant assisted reprecipitation technique, which possessed good reductive-oxidative ECL activity and performed a strong ECL emission around 626 nm at low potential (−1.10 V) in the presence of potassium persulfate. Thus, T-Ir was employed as a luminophore and good biocompatible matrix to load large amounts of capture antibodies (Ab1). Meanwhile, gold nanoparticles capped cuprous oxide nanocubes (Cu2O@Au) were used as the efficient quencher to label detection antibodies (Ab2). While different dosages of carcinoembryonic antigen (CEA) were introduced via sandwich immunoreaction, the ECL intensity was significantly dropped due to electrochemiluminescence resonance energy transfer from energy donor (T-Ir) to the acceptor (Cu2O@Au), achieving the highly sensitive detection of CEA. The proposed immunosensor showed a linear concentration range from 1 fg·mL−1 to 80 ng·mL−1 with a low limit of detection of 0.93 fg·mL−1 (S/N = 3). It featured superior stability, selectivity, reproducibility and practicability. With the successful demonstration of hydrophilic iridium(III)-based nanomaterials, sensing strategies for various biomarkers detection in diseases diagnosis will flourish.