Doped Nanomaterials Research Articles

Microwave assisted synthesis of ErxYbyCa1-x-yMoO4 nano-phosphor for efficient temperature sensing and catalytic applications

Here, Er/Yb Co-doped CaMoO4 materials (ErxYbyCa1−x−yMoO4 NPs where x = 0, 0.01 and y = 0, 0.05, 0.10, 0.15, 0.20) were prepared by microwave-assisted method and its pure-tetragonal structure were confirmed by X-ray diffraction spectra (XRD), Rietveld-refinement and Raman-vibrational spectra. The transmission-electron microscopy (TEM) study indicates the formation of nearly spherical shaped nanomaterial with average size of ~ 15 nm. Additionally, absorption and emission properties were studied by UV–Visible–NIR and photoluminescence (PL) spectrometer. The UV–Visible–NIR spectra attribute absorption of Er3+ ion in visible region (380–700 nm) and absorption of Yb3+ ion in near-infrared region (700–1400 nm). Moreover, PL up-conversion spectra of the sample recorded under excitation wavelength 980 nm. The PL peaks were observed at 530, 544–552, and 656–670 nm. Prominent PL-intensity was observed for Er0.01Yb0.15Ca0.84MoO4 phosphor. Temperature dependent PL study reveals that present phosphor is robust phosphor for temperature sensor. In addition, Er3+/Yb3+ doped CaMoO4 nanomaterials exhibited excellent activity and selectivity in the aerial oxidation of benzoin over benzyl under oxidant-free reaction conditions. The synergistic effect Er3+/Yb3+ co-doing in CaMoO4 matrix was observed, where only CaMoO4 material found to be inactive towards above oxidation reaction. Moreover, the oxidation of primary benzyl-alcohols was furnished in presence of tertiary butyl hydroperoxideas oxidant.

Structural and optical investigation of Nb5+-doped Sn3O4 for photoelectrochemical hydrogen production

We report herein, the microwave-assisted hydrothermal (MAH) synthesis of Nb5+-doped Sn3O4 nanoparticles for the photoelectrochemical production of hydrogen (H2). Nb5+ ions inside the Sn3O4 created structural defects, contributing to a local structural disorder, as confirmed by micro-Raman spectra. Photoluminescence spectroscopy indicated the decrease of the violet-blue–green visible emission after adding Nb5+, revealing the formation of alternative energy pathways for the electron/hole recombination. Through the morphological analysis, it was observed that the Nb5+ dopant slightly changed the morphology of nano-petals in Sn3O4. We demonstrate that the 3 % Nb5+ doped-Sn3O4 photoanode presented higher charge carrier mobility, higher photocurrent density, and an impressive H2 production of 1.50 mmol L−1 in a 3 h experiment, compared to the pure Sn3O4 material. The best performance of the Nb5+ doped Sn3O4 nanomaterial could be ascribed to the formation of new energy levels in the Sn3O4 band gap, thereby inhibiting the electron-hole pair recombination and positively affecting the photoelectrochemical response of the doped material.

Sr2BiF7: A New Bismuth-Based Host Material for Lanthanide Ions Doping: Synthesis, Downshifting, and Upconversion Luminescence Properties for Multimode Anticounterfeiting.

A new bismuth-based host material, i.e., Sr2BiF7, is explored in this work. Undoped and lanthanide ion-doped Sr2BiF7 nanomaterials are prepared using a simple coprecipitation technique at 120 °C. The undoped nanomaterials exhibit a blue color under 365 nm excitation. The downshifting and upconversion photoluminescent properties of Er and Yb codoped Sr2BiF7 nanomaterials are investigated. The optimum up-conversion luminescence is produced by nanomaterials doped with 5% Yb3+ and 0.2% Er3+. These nanomaterials show blue and magenta colors upon excitation at 365 and 395 nm wavelengths, respectively. Sr2BiF7 material doped with Er3+ shows green emission, while the codoped Er3+, Yb3+ nanomaterials exhibit an orange-red color under 980 nm light. A specific amount of polyvinyl chloride (PVC) is used for producing luminescent ink with these nanoparticles for multimode anticounterfeiting applications. The letters and patterns written with luminescent ink based on Er3+, Yb3+ doped nanomaterials show blue, magenta, and orange-red colors under 365, 395, and 980 nm light, respectively. These results establish that this material can be effectively used as a multimode photoluminescent covert tag to combat counterfeiting.

Investigation of antibacterial and anticancer activities of copper, aluminum and nickel doped zinc sulfide nanoparticles

First time compared the different metals doped ZnS nanoparticles for antibacterial and liver cancer cell line. In this study, copper, aluminum and nickel doped ZnS NPs were synthesized via co-precipitation method. The XRD analysis was confirmed the presence of cubic crystal structure and crystallite size decreased from 6 to 3 nm with doping elements. While as SEM micro-grains were revealed slightly irregular and agglomerated morphology with the presence of dopant elements. The presence of different dopant elements such as Cu, Al and Ni in ZnS NPs was identified via EDX analysis. The FTIR results demonstrate various vibrational stretching and bending modes attached to the surface of ZnS nanomaterials. After that the well diffusion method was used to conduct in-vitro bioassays for evaluation of antibacterial and anticancer activities against E.coli and B.cereus, as well as HepG2 liver cancer cell line. Our findings unveil exceptional results with maximum inhibition zone of approximately 9 to 23 mm observed against E.coli and 12 to 27 mm against B.cereus, respectively. In addition, the significant reduction in cell viability was achieved against the HepG2 liver cancer cell line. These favorable results highlight the potential of Ni doped ZnS NPs for various biomedical applications. In future, the doped ZnS nanomaterials will be suitable for hyperthermia therapy and wound healing process.

Solution combustion derived color-tunable Eu3+ doped Ca8ZnBi(VO4)7 nano sample for luminous devices and latent fingerprinting applications

Eu3+ doped Ca8ZnBi(VO4)7 host lattice have been produced through an environmentally friendly, economical, and energy-efficient solution combustion synthesis. The trigonal phase with the R 3c space group of the constructed series was verified by x-ray diffraction and Rietveld refinement technique. The elemental and morphological study was done by using energy dispersive X-ray analysis (EDAX) and scanning electron microscope (SEM), transmission electron microscope (TEM) respectively. In the excitation spectra, the intense band at 334 nm indicates the transfer of energy occur between VO43- → Eu3+. The color-tunable features of the generated nanosample are indicated by the emission (617 nm, 5D0→7F2) color of the nanophosphor, which lies in the yellow, orange, and red regions for varying doping amounts. The band gap was determined using Tauc’s hypothesis for both host lattice (3.18 eV) and Eu3+ doped nanomaterials (3.13 eV) which lie in the range of semiconductors. The use of Dexter’s theory and the Inokuti-Hirayama (I-H) model verified the existence of dipole–dipole (d-d) type interlinkages as a genuine phenomenon for concentration quenching. Additionally, Auzel’s system was used to study radiative lifetime (0.6510 ms), quantum efficiency (59.51 %), and non-radiative rates (621.8 s−1). The CIE coordinates (0.5164, 0.4703), lower value of correlated colour temperature (CCT) (2459 K) and color-tunable phenomena made it a possible choice for warm white light emitting luminous devices. The optimized nanophosphor has been investigated for latent fingerprinting and has been successful in identifying all of the fingerprint’s levels-1, 2 and 3.

Study of Concentration Quenching and Energy Transfer Mechanism in Ce Doped Y2O3 Nanomaterials.

We study concentration quenching and energy transfer mechanisms of yttrium oxide (Y2O3) nanomaterials doped with different concentrations (0-5mol%) of cerium (Ce). Photoluminescence (PL) spectra recorded under an excitation wavelength of 350nm show a broad emission band at ∼ 406nm and a feeble emission band at ∼ 463nm in the undoped Y2O3 sample. The doping of Ce in Y2O3 induced multiple PL peaks within the blue-green region of the spectrum in all the doped samples with the peak at ∼ 466nm being notably the prominent one. This prominent emission band exhibits a decrease in intensity with increasing Ce concentration due to concentration quenching. Analysis of Time-resolved photoluminescence (TRPL) spectra reveal that the average emission lifetime of Ce-doped Y2O3 is shorter than that of the undoped Y2O3 sample. The concentration quenching effect and the decrease of average emission lifetime of the dominant emission band are explained on the basis of energy transfer from the host Y2O3 to the Ce3+ ion centres. The critical quenching concentration of Ce3+ ion in Y2O3:Ce phosphor was identified to be 1mol% and the critical transfer distance was estimated to be 23.74 Å. Analysis reveal that the concentration quenching mechanism involves nearest-neighbour interaction.

A New Class of Multifunctional CoDyzFe2−zO4 Magnetic Nanomaterials: Influence of Structural, Morphological, Optical, Magnetic, Antibacterial, and Photocatalytic Traits

Here we focus on preparing recoverable Dy doped CoFe2O4 photocatalysts for the removal of the malachite green pollutant (MGP) in natural Sunlight. XRD results demonstrate development of the spinel symmetry with no impurities phases. The FESEM analysis revealed spherical grains with definite grain boundaries and agglomerated behavior. We found that our synthesized photocatalysts behaves as an excellent magnetic nanomaterial by observing the saturation magnetization of 77.79 emu g−1. Out of all photocatalysts, CoDy0.03Fe1.97O4 nanophotocatalyst exhibit the high zone of inhibition (ZOI) for Staphylococcus aureus and Escherichia coli. It makes the prepared nanomaterials highly suitable for the biological purposes. The effectiveness of photocatalytic degradation activity of prepared specimens is significantly impacted by the addition of dysprosium ions. During a 150 min of reaction period, CoDy0.03Fe1.97O4 has a higher degradation percentage around 95.36% as compared to CoFe2O4 (86.09%). The prepared doped and undoped CoFe2O4 nanomaterials displayed the least decline in the degradation percentage of MGP after four reuse cycles and this might be attributable to the weight loss during the recovery. Therefore, the nanomaterials suggested a reliable and durable photocatalyst for degradation process. Hence the prepared magnetically recoverable and multifunctional photocatalysts are reliable for the water remediation and biological usages.

Binary NiCu oxide nanoparticles onto graphite as promoting nanocatalysts for ethanol electro‐oxidation process

A facile and reduced cost fabrication protocol was followed to have a series of nickel oxide nanospecies onto graphite support with introducing varied copper oxide wt.% values (NiCuO/T). The co‐precipitation of metallic hydroxide particles onto carbonaceous surfaces and their subsequent burning at 400°C were sufficient to prepare mixed transition metal oxides. Suitable analysis tools were exploited to fully characterize the obtained nanopowders using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction spectroscopy, X‐ray photoelectron spectroscopy, and energy dispersive X‐ray analysis. Outstanding performances of the formed nanocatalysts for catalyzing ethanol electro‐oxidation reaction were measured especially in presence of 15 wt.% copper oxide content. The onset potential (Eonset) value of alcohol oxidation process was negatively shifted at dispersed NiO nanoparticles onto graphite after doping with copper oxide nanospecies. This promoted activity of prepared nanomaterials could be explained by their increased active sites when binary metallic oxides were incorporated. Electrochemical impedance spectroscopy studies demonstrated much lowered resistances in alkaline solution containing ethanol molecules to ascertain the enhanced behavior of NiCuO/T nanocatalysts. Moreover, their good stability attitude encouraged the application of doped nanomaterials with copper oxide for fuel cells application.

Two-dimensional nanomaterials based on rare earth elements for biomedical applications.

As a kind of star materials, two-dimensional (2D) nanomaterials have attracted tremendous attention for their unique structures, excellent performance and wide applications. In recent years, layered rare earth-based or doped nanomaterials have become a new important member of the 2D nanomaterial family and have attracted significant interest, especially layered rare earth hydroxides (LREHs) and layered rare earth-doped perovskites with anion-exchangeability and exfoliative properties. In this review, we systematically summarize the synthesis, exfoliation, fabrication and biomedical applications of 2D rare earth nanomaterials. Upon exfoliation, the LREHs and layered rare earth-doped perovskites can be dimensionally reduced to ultrathin nanosheets which feature high anisotropy and flexibility. Subsequent fabrication, especially superlattice assembly, enables rare earth nanomaterials with diverse compositions and structures, which further optimizes or even creates new properties and thus expands the application fields. The latest progress in biomedical applications of the 2D rare earth-based or doped nanomaterials and composites is also reviewed in detail, especially drug delivery and magnetic resonance imaging (MRI). Moreover, at the end of this review, we provide an outlook on the opportunities and challenges of the 2D rare earth-based or doped nanomaterials. We believe this review will promote increasing interest in 2D rare earth materials and provide more insight into the artificial design of other nanomaterials based on rare earth elements for functional applications.

Synthesis and optoelectronic aspects of orange-red light emitting Sm3+ doped vanadate nanomaterials for pc-WLEDs

Synthesis and optoelectronic aspects of orange-red light emitting Sm3+ doped vanadate nanomaterials for pc-WLEDs

Structural, ferromagnetic, ferroelectric, and bio-medical behaviour of yttrium doped strontium hexaferrite (SrFe12-xYxO19) nano materials, assisted with sol-gel cost effective technique

Rare earth Yttrium (Y3+) substituted strontium hexaferrite (SrFe12-xYxO19) with X = (0.25–1.0), is synthesized using an economical and chemical-based sol–gel technique. The reflected planes in the XRD patterns justify that samples possessed hexagonal symmetry (P63/mmc space group). Crystallite size and strain calculations for SrFe12-xYxO19 samples were performed with a W-H plot. Lattice constants change minutely but regularly with Y3+ composition. The morphological structure of the sample SrFe12O19, SrFe11.50Y0.50O19, and SrFe11Y1O19 have been visualized from SEM micrographs, which reveal hexagonal crystal symmetry, possessing agglomeration with an average particle size of 49.84 nm, 73 nm, and 39.66 nm respectively. TEM, HRTEM, and SAED have been performed for confirming the lattice fringe distance, the grain size of nanoparticles (NPs), and diffraction planes. Grain size is 44.15 nm and 37.27 nm for X = 0.00 and X = 1.0 composition of Y3+. Raman spectral pattern exhibited that all the peak of the synthesized sample is indexed to Raman vibration modes and strontium hexaferrite (SHF) structure. FTIR analysis supports the stretching of metal-oxygen bonding and helps to find the force constant, bond length, and functional group of samples. The highest luminescent peak is observed at 481 nm, using the PL spectrum. Using UV-Visible spectroscopy direct band gap (Eg) of the synthesized sample was evaluated and is found to decrease from 2.3 eV-1.93 eV with Y3+ concentration. With an increase in the composition of non-magnetic ions of Y3+, Ms and Mr parameters decrease systematically. In contrast, the coercivity value increases drastically from 5983–6595 Oe and is one of the novel works of this report. The occupancy of Y3+ ions in SrFe12-xYxO19 lattice obstructs electrical leakage to generate remnant polarization (Pr) and coercive polarization (Pc) of values 25.45 μC cm−2 and 2.91 kV cm−1 respectively. Moreover, cytotoxicity assay reveals that at lower concentrations up to 250 μg ml−1, the synthesized material SrFe12-xYxO19 for X = 0.00 and X = 1.0 promotes the growth of cell and hence represents non-toxic and biocompatible behavior with cell. Hence anticipation can be made that it may be used for biological and biomedical applications such as bone replacement, magnetic drug delivery, and coating on metal implants. Thus, improved physical properties of Y3+ doped SHF nanomaterials pave the way for promising optical, magnetic, electrical, biological, and biomedical applications.

Nanocomposite Electrodes and Membranes for PEM Electrolysis

Reducing the iridium loading while keeping high mass activity and durability is one of the greatest challenges for PEMWE development.[1] Amongst the strategies to achieve this central goal, supporting iridium oxide on metal oxide supports offers high resistance to corrosion as well as electronic electrocatalyst-support interactions beneficial for catalyst activity and durability.[2] The morphology of the supports also plays a crucial role in the control of architecture and porosity of the catalyst layers.Here, tin oxide materials doped with aliovalent ions (niobium, antimony and tantalum)[3,4] were prepared by electrospinning leading to a fibre-in-tube morphology. The doping led to increase of the intrinsically low electrical conductivity of the semiconductor oxide. The electrochemical stability of the different supports was evaluated in acidic medium at low and high potentials, coupling electrochemistry and spectroscopic methods.[5] IrO2 nanoparticles synthesized by a microwave-assisted polyol method were deposited onto the doped SnO2 nanomaterials. Their electrochemical activity towards the oxygen evolution reaction (OER) as well as their durability upon accelerated stress tests were evaluated.In order to enhance the PEMWE performance, the use of thin membranes reducing resistive effects is crucial. To avoid premature failure and gas permeability issues, reinforcing polymer nanofibrous webs were introduced in the PFSA matrix.[6] The nanocomposite membranes obtained led to greater mechanical robustness and reduced gas crossover while keeping high proton conductivity. [7]The nanocomposite electrocatalysts and membranes were used to prepare membrane-electrode assemblies and characterised in a PEMWE cell. Their performance and stability were investigated in different operating conditions and will be discussed. Daiane Ferreira da Silva, C.; Claudel, F.; Martin, V.; Chattot, R.; Abbou, S.; Kumar, K.; Jiménez-Morales, I.; Cavaliere, S.; Jones, D.; Rozière, J.; et al. Oxygen Evolution Reaction Activity and Stability Benchmarks for Supported and Unsupported IrO x Electrocatalysts. ACS Catal. 2021, 11, 4107–4116.Du, L.; Shao, Y.; Sun, J.; Yin, G.; Liu, J.; Wang, Y. Advanced catalyst supports for PEM fuel cell cathodes. Nano Energy 2016, 29, 314–322.Cavaliere, S.; Jiménez-Morales, I.; Ercolano, G.; Savych, I.; Jones, D.; Rozière, J. Highly Stable PEMFC Electrodes Based on Electrospun Antimony-Doped SnO2. ChemElectroChem 2015, 2, 1966–1973.Jiménez-Morales, I.; Haidar, F.; Cavaliere, S.; Jones, D.; Rozière, J. Strong Interaction between Platinum Nanoparticles and Tantalum-Doped Tin Oxide Nanofibers and Its Activation and Stabilization Effects for Oxygen Reduction Reaction. ACS Catal. 2020, 10, 10399–10411.Jiménez-Morales, I.; Cavaliere, S.; Dupont, M.; Jones, D.; Rozière, J. On the stability of antimony doped tin oxide supports in proton exchange membrane fuel cell and water electrolysers. Sustain. Energy Fuels 2019, 3, 1526–1535.Sood, R.; Cavaliere, S.; Jones, D.J.; Rozière, J. Nano Energy Electrospun nano fi bre composite polymer electrolyte fuel cell and electrolysis membranes. Nano Energy 2016, 26, 729–745.Sood, R.; Giancola, S.; Donnadio, A.; Zatoń, M.; Donzel, N.; Rozière, J.; Jones, D.J.; Cavaliere, S. Active electrospun nanofibers as an effective reinforcement for highly conducting and durable proton exchange membranes. J. Memb. Sci. 2021, 622.

Doped Ceria Nanomaterials: Preparation, Properties, and Uses.

Doping is a powerful strategy for enhancing the performance of ceria (CeO2) nanomaterials in a range of catalytic, photocatalytic, biomedical, and energy applications. The present review summarizes recent developments in the doping of ceria nanomaterials with metal and non-metal dopants for selected applications. The most important metal dopants are grouped into s, p, d, and f block elements, and the relevant synthetic methods, novel properties, and key applications of metal doped ceria are collated and critically discussed. Non-metal dopants are similarly examined and compared with metal dopants using the same performance criteria. The review reveals that non-metal (N, S, P, F, and Cl) doped ceria has mainly been synthesized by calcination and hydrothermal methods, and it has found applications mostly in photocatalysis or as a cathode material for LiS batteries. In contrast, metal doped ceria nanomaterials have been prepared by a wider range of synthetic routes and evaluated for a larger number of applications, including as catalysts or photocatalysts, as antibacterial agents, and in devices such as fuel cells, gas sensors, and colorimetric detectors. Dual/co-doped ceria containing both metals and non-metals are also reviewed, and it is found that co-doping often leads to improved properties compared with single-element doping. The review concludes with a future outlook that identifies unaddressed issues in the synthesis and applications of doped ceria nanomaterials.

Synthesis of Nickel-doped Magnesium spinel ferrites (NixMg1-xFe2O4) nanomaterials and study of their structural, electrical and magnetic properties

The Solution-gelation self-ignition method was used to synthesize Nickel-doped Magnesium ferrite (MgFe2O4) nanoparticles with the formula NixMg1-xFe2O4, where x ranged from 0.00 to 0.20 with a step/sample of x = 0.05. Nickle was doped to tune the magnesium ferrite's dielectric and magnetic properties and the systematic effect of Ni on crystal structure, crystallite size, dielectric properties in high-frequency range, and magnetic properties was investigated. The prepared samples were annealed at 600 °C for 3 h and their electrical properties were investigated through pellets of each ferrite. The crystalline host material structure was confirmed using X-ray Diffraction (XRD) characterization, which showed a Face-centered cubic lattice (FCC) structure with a preferred orientation along the (311) plane. The crystallite size was found to be between 10 and 16 nm using Scherrer's formula, modified Scherrer's formula, Williamson-Hall's plot, and Size strain plot. FTIR analysis was used to identify the doped spinel ferrite nanomaterials and the spectral qualities were successfully verified. Transmission electron microscopy (TEM) was used to analyze the size of particles and their distribution. The magnetic properties of NixMg1-xFe2O4 were analyzed using the VSM technique between the field of −23 kOe to 23 kOe, and the remanent magnetization (Mr), coercive field (Hc), and saturation magnetization (Ms) were estimated. The dielectric properties of the host material were studied using an Impedance analyzer, which showed that the complex impedance (Z′ & Z″) decreased with an increasing frequency corresponding to the grain boundary action. The dielectric constant improved ferromagnetic resonance and dielectric loss-enhanced relaxations. The ac conductivity appeared to increase by increasing frequency. The dielectric studies suggested that Mg1-xNixFe2O4 nanoparticles would have potential applicability in many microwave devices.

Co supported on N and S dual-doped reduced graphene oxide as highly active oxygen-reduction catalyst for direct ethanol fuel cells

Oxygen reduction reaction (ORR) is one of the key features for the efficient functioning of several energy conversion devices such as fuel cells, appearing the necessity of development of new low-cost catalyst materials. Heteroatom-doped carbon materials have attracted attention in this field due to its physicochemical and electronic properties. In this work, a nitrogen and sulfur doped material with anchored Co3O4 nanoparticles (Co/SN-rGO) is proposed as cathode catalyst for direct ethanol fuel cells (DEFCs) and results are compared with different doped graphene nanomaterials (GMs). The effect of the heteroatoms and cobalt oxide nanoparticles in the final efficiency was studied. Synthesized materials were characterized and the activity of Co/SN-rGO and GMs for the ORR was studied. Co/SN-rGO presents high ORR performance in terms of onset potential (Eonset), 0.86 V (vs RHE) and half-wave potential (E1/2) 0.72 V (vs RHE). Tafel analysis shows 60 mV dec-1 at low overpotential for potential dependent ORR mechanism. Besides, when Co/SN-rGO performance is evaluated in a DEFC using a fuel cell test station, main results indicate higher catalytic activity, stability, and ethanol tolerance of Co/SN-rGO in comparison to a carbon-supported Pt catalyst.

Fe Doped Ga2O3 Nanomaterial Catalysed Green and Efficient One Pot Three Component Synthesis of Tetrahydrobenzo[b]pyran

Abstract:The present work reports the hydrothermal synthesis of Fe doped gallium oxide nanoparticles and its characterization by IR, XRD, SEM, and EDX techniques. The characterization of Fe doped gallium oxide nanomaterial reveals the 18.58 nm particle size with monoclinic phase. The catalytic activity of nanomaterial was efficiently assessed for one-pot domino Knoevenagel and Michael's addition of different aldehydes, dimedone, and malononitriles to give tetrahydrobenzo [b] pyran derivatives. The remarkable features associated with this green protocol are good to excellent product yields (60-94%), non-chromatographic purification of product, shorter reaction time, and easy work up. The reusability and non-toxic nature of this nanomaterial catalyst escalate the importance of this work.

Oxygen-vacancy europium-doped MnO2 ultrathin nanosheets used as asymmetric supercapacitors

In term of supercapacitors application, MnO2 has been recognized as a popular pseudocapacitive material on account of its environmental friendliness, cost inexpensive, plentiful abundance and high theoretical capacitance. However, its inherently low conductivity and structural instability lead to low specific capacitance and short cycle life, which greatly limit its development. Rare-earth doping can manipulate the size, shape, and crystallographic phase of doped nanomaterials. For the sake of hoisting the supercapacitors performance of MnO2, herein, we synthesized europium-doping MnO2 (Eu5%-MnO2) ultrathin nanosheets (3.4 nm) possessing rich oxygen vacancies via a facile co-precipitation strategy. The specific capacitance of Eu5%-MnO2 at 1 A g−1 is 361.2 F g−1 and remains 100% after 10,000 cycles, outperforming of MnO2 nanosheets (198 F g−1, 82.8%). The reason of enhancing performance may be mainly correlation to the heighten conductivity, boosted surface reactivity and electrochemical active sites. The assembled Eu5%-MnO2//AC device at 1 A g−1 can reach 63.36 F g−1 with high voltage of 3 V and exerts 19.8 Wh kg−1 of energy density when the power density is 373.2 W kg−1. This synthesis technique is a simple and convenient means for the development of high-performance MnO2-based energy storage electrodes.

Enhanced magnetic and ferroelectric properties of La[formula omitted]M[formula omitted]FeO[formula omitted] (M = Dy and Y) nanoparticles: A comparison of A-site doping

The room temperature magnetic hysteresis (M-H) loops reveal ferromagnetic-like behavior in an antiferromagnetically ordered LaFeO3 (LFO) material system synthesized by the sol–gel method. The maximum magnetization (Mmax) for the undoped sample annealed at 800 °C is 1.08 emu/g, whereas, with the same annealing, materials that are Dy and Y doped (25%) exhibit four times higher magnetization. It is interesting to note that non-magnetic ion Y3+ doped LFO has the same magnetization as magnetic ion Dy3+ doped nanomaterials. Reduction of particle and crystallite size plays a significant role in enhancing the net magnetization of doped materials. While the magnetization in Y-doped materials is attributed to the anti-symmetric exchange interaction (AEI) through spin canting, the greater magnetization for Dy doped samples is related to the AEI as well as inherent magnetic moment of the Dy3+ ion. The quantified tilting angle (Fe–O–Fe) is higher and the bond length (Fe–O) is smaller for Y-doped compounds compared to Dy-doped samples. X-ray photoelectron spectroscopy for oxygen 1s spectra shows that the relative area of O1− is higher in Dy-doped LFO than Y-doped sample. Ferroelectric hysteresis loops exhibit spontaneous electric polarization with reduced leakage current for Y-doped LFO, while other compounds show leaky behavior.

Observation of Phonon Cascades in Cu-Doped Colloidal Quantum Wells.

Electronic doping has endowed colloidal quantum wells (CQWs) with unique optical and electronic properties, holding great potential for future optoelectronic device concepts. Unfortunately, how photogenerated hot carriers interact with phonons in these doped CQWs still remains an open question. Here, through investigating the emission properties, we have observed an efficient phonon cascade process (i.e., up to 27 longitudinal optical phonon replicas are revealed in the broad Cu emission band at room temperature) and identified a giant Huang-Rhys factor (S ≈ 12.4, more than 1 order of magnitude larger than reported values of other inorganic semiconductor nanomaterials) in Cu-doped CQWs. We argue that such an ultrastrong electron-phonon coupling in Cu-doped CQWs is due to the dopant-induced lattice distortion and the dopant-enhanced density of states. These findings break the widely accepted consensus that electron-phonon coupling is typically weak in quantum-confined systems, which are crucial for optoelectronic applications of doped electronic nanomaterials.

Doped Ferrite Nanoparticles Exhibiting Self-Regulating Temperature as Magnetic Fluid Hyperthermia Antitumoral Agents, with Diagnostic Capability in Magnetic Resonance Imaging and Magnetic Particle Imaging.

Simple SummaryHyperthermia, a limited increase in tumor tissue temperature up to a maximum of 45 °C, has long been used in cancer treatment, either as a stand-alone therapy or in conjunction with chemo-/radiotherapy. Among the different physical procedures used, a particularly promising technique is magnetic fluid hyperthermia (MFH): this consists of the local administration of magnetic nanoparticles, followed by the application of alternating magnetic fields. One concern with this technique is the possibility of damage to healthy peritumoral tissue. The present study investigates innovative nanoparticles with self-regulating temperature, which should reduce this risk and thus mark a significant step forward in MFH. In an experimental model of aggressive breast cancer, we demonstrated a substantial reduction of tumor growth rate by using an experimental MFH protocol, transferable to clinical practice. These innovative nanomaterials present the added advantage of allowing non-invasive monitoring of temperature, by magnetic resonance imaging (MRI) and magnetic particle imaging (MPI).This paper reports a comprehensive investigation of a magnetic nanoparticle (MNP), named M55, which belongs to a class of innovative doped ferrite nanomaterials, characterized by a self-limiting temperature. M55 is obtained from M48, an MNP previously described by our group, by implementing an additional purification step in the synthesis. M55, after citrate and glucose coating, is named G-M55. The present study aimed to demonstrate the properties of G-M55 as a diagnostic contrast agent for MRI and magnetic particle imaging (MPI), and as an antitumoral agent in magnetic fluid hyperthermia (MFH). Similar specific absorption rate values were obtained by standard MFH and by an MPI apparatus. This result is of interest in relation to the application of localized MFH by MPI apparatus. We demonstrated the biocompatibility of G-M55 in a triple-negative human breast cancer line (MDA-MB-231), and its efficacy as an MFH agent in the same cell line. We also demonstrated the efficacy of MFH treatment with G-M55 in an experimental model of breast cancer. Overall, our results pave the way for the clinical application of G-M55 as an MFH agent in breast cancer therapy, allowing not only efficient treatment by both standard MFH apparatus and MPI but also temperature monitoring.