Doped Nanomaterials Research Articles

Au5Br: A new member of highly stable 2D-type doped gold nanomaterial

A new potential relatively highly stable two-dimensional (2D) type naonomaterial of doped gold nanoclusters, Au5Br, is reported. The nanomaterial is obtained by searching bromine-doped neutral gold clusters through the CALYPSO software together with DFT method. The structural study of AunBr (n = 2–13) nanoclusters indicates that the geometrical transition size of the lowest energy structures from 2D to three-dimensional (3D) is Au6Br, and the 3D structures of AunBr (n = 7–13) are all based on the multilayer pyramid-type. The research on the relative stability of the ground state of the AunBr (n = 2–13) clusters reveals that these clusters are odd-sized number stable. Interestingly, the most special one is Au5Br with 2D triangle geometry, which has the strongest local stability and can be used as a candidate for magic cluster. The calculations of the natural charge population (NCP) in all the lowest energy clusters show that all bromine atoms are negatively charged. Polarization analysis strongly suggests that Au4Br nanocluster’s nonlinear optic properties is probably particular better than other nanoclusters. Finally, in order to further understand the high stability properties of Au5Br nanocluster, its molecular orbitals (MOs), electronic localization function (ELF), infrared (IR) and Raman spectra are also studied in detail.

Transition metal ions doped Bi12SiO20 as novel catalysts for the decomposition of hydrogen peroxide (H2O2)

To the best of our knowledge there are no research in the literature on the catalytic hydrogen peroxide (H2O2) decomposition utilizing the pure Bi12SiO20 (BS) and transition metal ions doped Bi12SiO20 (M/BS; M = Fe, Cu, Ni, Co or Mn) as catalysts. The effect of transition metal ions doping on the crystal structure, morphology, surface and porous properties of Bi12SiO20 nanomaterial was estimated by the XRD, TEM and BET analysis. Interestingly, the doped nanomaterials possessed bigger specific surface areas and larger pore volumes than that of pure BS nanomaterial. Noteworthy, the catalytic performance of Bi12SiO20 catalyst was gradually promoted in the existence of the different transition metal ions as dopants. Interestingly, the performance of Bi12SiO20 catalyst was remarkably promoted with NiO, Co3O4 and Mn3O4 doping by conversion about 38.1% 41.9% and 71.4%, respectively. Furthermore, the H2O2 decomposition conversion was found to be 71.4, 82.9 and 90.5% on the most active catalyst (Mn/BS) at 20 °C, 35 °C and 50 °C, respectively. Finally, the Mn/BS catalyst demonstrated larger stability in the H2O2 decomposition and can be recycled several times.

Gemini surfactant assisted synthesis of mesoporous Mn/Mg bimetal doped TiO2 nanomaterial: characterization and photocatalytic activity studies under visible light irradiation

The present work mainly aimed to synthesize different weight percentages (0.25–1.00 wt%) of Manganese (Mn2+) and Magnesium (Mg2+) bimetal ions doped TiO2 nanomaterial assisted with different weight percentages (5–15 wt%) of Gemini surfactant (GS) using sol-gel method. The bimetal doped and undoped TiO2 photocatalysts were characterized by X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), UV-Visible Diffused Reflectance Spectroscopy, Transmission Electron Microscopy, Brunauer-Emmett-Teller surface area analyzer, and Photoluminescence Spectroscopy. Characterization results revealed that mesoporous multi-particle anatase TiO2 nanoparticles with a narrowed band gap, small particle size, and high surface area were formed due to the combined effect of Mn2+/Mg2+ bimetal ions doping and effective encapsulation of GS over the initially formed TiO2 nanoparticles. The surface elemental composition of the 0.25 wt% Mn2+ and 1.00 wt% Mg2+ bimetal doped TiO2 in the presence of 10 wt% of GS (after calcination) revealed the presence of both the metal dopants Mn2+ and Mg2+ along with the Ti and O and their chemical interactions were further confirmed by FT-IR results. The photocatalytic activity of these catalysts was assessed by the degradation of Methyl Red using visible light irradiation. To understand the effect of different reaction parameters on the photocatalytic activity of the nanocatalysts such as the dopant concentration, surfactant concentration, catalyst dosage, solution pH, and initial dye concentration were investigated and optimized to achieve the best performance. The photoluminescence results conclude that OH radicals are the crucial reactive species responsible for oxidative photocatalytic degradation of Methyl Red.

Atomic-scale chemical mapping of copper dopants in Bi2Te2.7Se0.3 thermoelectric alloy

Elemental doping is a universal strategy in controlling the functionalities of materials that strongly correlate with naturally formed atomic defects. Element-resolved chemical mapping for atomic defects has answered numerous problems on the relations between defective structures and properties. However, tracking small amounts of dopants in multicomponent bulks and clarifying their doping behaviors remain challenging. Using advanced X-ray spectroscopy, the excess Cu doping behavior in ternary Bi2Te2·7Se0.3 bulk alloy is visualized with the unprecedented detectability from sub-one atomic percent of concentration. The low content of 0.2 at.% Cu preferentially occupies the Bi site, while Cu atoms are found in three crystallographic sites of Bi2Te3 structure and van der Waals gap at high Cu content of 1.2 at.%. These behaviors explain the nontrivial role of Cu dopants on carrier generation processes and relevant thermoelectric properties of Bi2Te2·7Se0.3. The atomic-level identification should also stimulate the elucidation of diverse properties in doped nanomaterials and quantum phenomena in doped topological insulators.

Generation of nanomaterials in dopant-containing liquid via pulsed laser ablation

Nanoparticles of ZnS doped with Cu were prepared by means of pulsed laser ablation in liquid medium containing Cu ions. Nanosecond pulsed laser was focused on Zn target immersed in mercaptoethanol with copper nitrate dissolved as a source of Cu ions. X-ray diffraction and X-ray photoelectron spectroscopy confirmed formation of wurtzite ZnS structures as the main product, while up to ~5% of Zn atoms were substituted by Cu when ≤1.0 mM Cu(NO3)2 in mercaproethanol was used as liquid medium. Elemental mapping revealed that dopant Cu atoms were uniformly distributed in the produced nanoparticles. Photoluminescence recorded from the doped nanomaterial exhibited an additional green emission, indicating the presence of interband states resulted from doping with Cu2+. Compared with undoped ZnS nanoparticles, their Cu-doped counterparts demonstrated more efficient photocatalytic behavior toward the decomposition of methylene blue (as model organic compound), which is believed to be caused either by more efficient light absorption extended into the visible region or by the carriers based on the Cu2+ state. The present study demonstrates that the technique used has the capacity of producing doped nanomaterials in one step by incorporating dopants from the liquid phase, which may be promising for preparing novel unique nanomaterials with complex composition.

Synthesis and characterization of dysprosium (Dy3+) doped titanium dioxide (TiO2) as a potential material for photocatalytic activity

Doping Dysprosium (Dy3+) (2 wt%) by employing one step and one pot hydro thermal method with TiO2 nano particles form a potential composition for photo catalysis. Dy3+ doped TiO2 nano particles are obtained using the methodical synthesis and the resulted product is subjected to various studies like XRD, HR-TEM and UV to understand its structure, morphology and the bandgap. The narrower bandgap resulted by the doped nano material proves to be better than its purest form (TiO2). It is acknowledged through UV analysis. The above synthesized material’s photo catalytic degradation is carried out against the organic and inorganic contaminations present in waste water.

Feasibility study of doped SnO2 nanomaterial for electronic nose towards sensing biomarkers of lung cancer

Feasibility study of doped SnO2 nanomaterial for electronic nose towards sensing biomarkers of lung cancer

Process intensification for rare-earth doped luminescent nanomaterials

Process intensification for rare-earth doped luminescent nanomaterials

Tailoring the tunable luminescence from novel Sm3+ doped SLAO nanomaterials for NUV-excited WLEDs

Color tunable nanophosphors are still largely favored materials for easy fabrication of white LEDs (light emitting diodes) with exemplary attributes like color reproducibility, purity and better quantum efficiency. Herein, we report a unique down-conversion color tunable Sm3+ doped SrLaAlO4 nanomaterial, synthesized by urea combustion approach. Crystal structure was studied systematically by powder X-ray diffractometry and Rietveld Analysis. Under near UV irradiation, the nanophosphor showed scarlet emission with a high color purity (82.16%) and quantum efficiency (77.86%). Color coordinates justified the versatile luminescence from blue to white to scarlet region effectively, thus widen the new prospects for NUV-excited white LEDs.

Decoupling and Coupling of the Host-Dopant Interaction by Manipulating Dopant Movement in Core/Shell Quantum Dots.

Doping through the incorporation of transition metal ions allows for the emergence of new optical, electrical, and magnetic properties in quantum dots (QDs). While dopants can be introduced into QDs through many synthetic methods, the control of dopant location and host-dopant (H-D) coupling through directional dopant movement is still largely unexplored. In this work, we have studied dopant behaviors in Mn:CdS/ZnS core/shell QDs and found that dopant transport behavior is very sensitive to the temperature and microenvironments within the QDs. The migration of Mn toward the alloyed interface of the core/shell QDs, below a temperature boundary (Tb) at ∼200 °C, weakens the H-D interactions. At temperatures higher than the Tb, however, dopant ejection and global alloying of CdS/ZnS QDs can occur, leading to stronger H-D coupling. The behavior of incorporated dopants inside QDs is fundamentally important for understanding doping mechanisms and the host-dopant interaction-dependent properties of doped nanomaterials.

Rare earth Ce- and Nd-doped spinel nickel ferrites as effective heterogeneous catalysts in the (ep)oxidation of alkenes

Cerium (Ce)- and neodymium (Nd)-doped spinel nickel ferrites catalysts system were synthesized using a cost-effective sol–gel route. The as-prepared nickel ferrites and its doped Ce and Nd nanomaterials were characterized in terms of Fourier transform infrared spectrophotometry, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, selected area diffraction pattern, zeta potential and magnetism techniques. Their catalytic potential was examined in the (ep)oxidation of 1,2-cyclooctene by using hydrogen peroxide (H2O2) or tert-butylhydroperoxide (t-BuOOH). Optimization of various parameters, including solvent, oxidant and catalyst type revealed that chloroform (CHCl3) or 1,2-dichloroethane as a solvent and t-BuOOH as an oxidant were found to be the best choice for this catalytic system. The catalytic efficiency was found as Nd–NiFe2O4 > Ce–NiFe2O4 > NiFe2O4. Further, the applied nanocatalysts could be easily renovated and exhibited high catalytic reactivity for 5 times of recycling experiments with long-time durability. A reasonable discussion of the mechanism reaction reinforced the action of these spinel catalysts.

Influence of Fe and Ni Doped CuO Nanomaterials for High Performance Supercapacitors

This paper focuses on the synthesis of doped and undoped CuO nanoparticles using the sol-gel method, which has been prepared and described. Supercapacitor applications of as-synthesized nanomaterials were analyzed using cyclic voltammetry (CV), galvanostatic discharge (GCD) and electrochemical impedance spectroscopic (EIS) analysis. The cyclic voltammograms illustrated the quasi-rectangular shape which depicted the pseudocapacitance nature of the samples. The calculated specific capacitance of the prepared samples was 180, 253 and 303 (F/g) corresponding to CuO, Fe-CuO and Ni-CuO, respectively at the low current density and the EIS spectra show that the prepared Ni-CuO electrode exhibits low charge transfer resistance.

α-glucosidase inhibition (antidiabetic) of rubidium doped indium sulfide nanomaterials

Herein, we report the In2S3 and rubidium doped In2S3 (Rb- In2S3) nanostructures and elucidate their role in α-glucosidase inhibition (AIGs). The phase, crystal structure, morphology, and composition of the as prepared In2S3 and Rb- In2S3 nanostructures was characterized by PXRD, SEM, TEM and EDS analysis, respectively. Pure In2S3 were unable to impart significance glucosidase inhibition activity, while the activity was remarkably enhanced with the doping of 5% Rb. The mass percentage of Rb (0.42 μg ml−1) is much lower than the transition metals-based drugs reported in the literature.

Auto-combustion synthesis of pure and Er, Dy co-doped ZnO nanomaterials for efficient methyl orange degradation using solar and visible light photocatalysis

Pure and Er-Dy co-doped ZnO nanomaterials (EDZ) were synthesized using auto combustion method. The obtained materials were used as photocatalysts for methyl orange (MO) degradation by solar irradiation and visible light (λ > 420 nm). The synthesized materials were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), Uv-visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL) and cyclic voltammetry (CV) measurements. XRD revealed highly crystalline hexagonal wurtzite structures. The crystallite size enhanced with Er and Dy dopants. DRS analyses revealed that energy gap (Eg) values for doped (Er 2.5%-5%+ Dy 2.5%–5%) nanoparticles were in the range 3.16–3.20 eV, showing a decreasing trend with increasing dopant concentrations. The CV measurements showed enhanced conductivity of doped nanomaterials than pure ZnO. The best photocatalytic activity was demonstrated by nanomaterials having the highest concentration of doping i. e. Zn0.90 Er0.05 Dy0.05O. The temperature dependent dielectric constant and tangent loss decreased with applied frequency for all prepared materials in general.

Zinc-Doped Copper Oxide Nanocomposites Inhibit the Growth of Pancreatic Cancer by Inducing Autophagy Through AMPK/mTOR Pathway.

Zinc doped copper oxide nanocomposites (Zn-CuO NPs) is a novel doped metal nanomaterial synthesized by our group using the sonochemical method. Our previous studies have shown that Zn-CuO NPs could inhibit cancer cell proliferation by inducing apoptosis via ROS-mediated pathway. In the present study, we studied the anticancer effect of Zn-CuO NPs on human pancreatic cancer cells. MTS assay revealed that Zn-CuO NPs was able to inhibit cancer cell growth. TEM, flow cytometry and fluorescence microscope analysis showed that Zn-CuO NPs induced autophagy significantly; the number of autophagosomes increased obviously in cells treated with Zn-CuO NPs. Western blot analysis revealed that treatment with the NPs resulted in activation of AMPK/mTOR pathway in both AsPC-1 and MIA Paca-2 cells in dose dependent manners. Moreover, in the presence of AMPK activator AMPKinone, the protein level of p-AMPK, p-ULK1, Beclin-1 and LC3-II/LC3-I increased, while the protein expression of p-AMPK, p-ULK1, Beclin-1 and LC3-II/LC3-I decreased in the presence of AMPK inhibitor Compound C. In vivo study using xenograft mice revealed that Zn-CuO NPs significantly inhibited tumor growth with low toxicity. Our study confirms that Zn-CuO NPs inhibit the tumor growth both in vitro and in vivo for pancreatic cancer. AMPK/mTOR pathway plays an important role in the NPs induced inhibition of tumor growth.

Preparation, characterization, and photocatalytic activity under UV and visible light of Co, Mn, and Ni mono-doped and (P,Mo) and (P,W) co-doped TiO2 nanoparticles: a comparative study.

In this work, TiO2-based nanomaterials have been successfully synthesized by doping TiO2 with Co, Mn, and Ni and by co-doping it with (P,Mo) or (P,W). The structural, optical, and morphological properties of the synthesized nanomaterials have been investigated using various techniques such as XRD, FTIR spectroscopy, UV-vis diffuse reflectance spectroscopy, XPS, and SEM-EDS. The obtained results showed that the crystalline structure of the doped TiO2-based nanomaterials depends strongly on the nature of the doping ions. The obtained band gap energy of TiO2 co-doped with (P,Mo) changes to a level below the band gap energy of TiO2 anatase indicating a high ability to absorb visible light. The obtained photocatalytic activity results of methyl orange degradation showed that, under visible light, the mono-doping of TiO2 with Co and its co-doping with (P,Mo) or (P,W) improve significantly the photocatalytic activity of TiO2 in comparison with undoped TiO2. The activity order obtained under UV-A irradiation for the used photocatalysts is TiO2 > > 1%Ni-TiO2 > 1%Co-TiO2 > 30%(P,Mo)-TiO2 ≈ 30%(P,W)TiO2 > 1%Mn-TiO2 while under visible light, it is 1%Co-TiO2 > 30%(P,Mo)-TiO2 > 30%(P,W)TiO2 ≈ TiO2 > 1%Ni-TiO2 > 1%Mn-TiO2. The high photocatalytic activity observed for these samples could be the result of a synergetic effect of the high visible light absorption capacity and the low recombination rate of photoexcited electrons and holes.

Overcoming Old Scaling Relations and Establishing New Correlations in Catalytic Surface Chemistry: Combined Effect of Charging and Doping

Optimization of catalytic materials for a given application is greatly constrained by linear scaling relations. Recently, however, it has been demonstrated that it is possible to reversibly modulate the chemisorption of molecules on nanomaterials by charging (i.e., injection or removal of electrons) and hence reversibly and selectively modify catalytic activity beyond structure–activity correlations. The fundamental physical relation between the properties of the material, the charging process, and the chemisorption energy, however, remains unclear, and a systematic exploration and optimization of charge-switchable sorbent materials is not yet possible. Using hybrid DFT calculations of CO2 chemisorption on hexagonal boron nitride nanosheets with several types of defects and dopants, we here reveal the existence of fundamental correlations between the electron affinity of a material and charge-induced chemisorption, show how defect engineering can be used to modulate the strength and efficiency of the adsorption process, and demonstrate that excess electrons stabilize many topological defects. We then show how these insights could be exploited in the development of new electrocatalytic materials and the synthesis of doped nanomaterials. Moreover, we demonstrate that calculated chemical properties of charged materials are highly sensitive to the employed computational methodology because of the self-interaction error, which underlines the theoretical challenge posed by such systems.

Rare earth doped semiconductor nanomaterials and its photocatalytic and antimicrobial activities

Investigations on dually active rare earth doped ZnO nanomaterials for enhanced photocatalytic and anti-microbial activity were conducted. Dy3+ doped ZnO was synthesised via a co-precipitation method. The dopant concentrations were varied from 3 to 10 wt% and characterised by XRD, FT-IR, UV–vis-DRS, PL, FE-SEM, EDAX, HR-TEM, AFM, BET, XPS and EPR techniques. The prepared material was found to be in the nano regime (38–47 nm) displaying hexagonal morphology. Surface roughness was also very high (47.49 nm) as confirmed by AFM. EPR confirmed that OH radicals were generated on light irradiation. The prepared photocatalysts were investigated for Visible and UV induced photocatalytic activities for the degradation of model pollutants like OrG and MG dye. The 10DZ nanomaterial displays 99.5% of degradation of OrG, similarly more than 94% of degradation of MG was observed under UV and Visible light irradiation. The degradation of OrG and MG was carried out for standard TiO2 under UV and Visible light irradiation and the results proves that 10DZ exhibits better photocatalytic activity than TiO2. The nanomaterial was screened for its anti-microbial activities against certain species of bacterial and fungal species. 10% doped nanomaterial was found to posses excellent photocatalytic activities both under Visible and UV light irradiation. The reaction followed a pseudofirst order kinetics. The activities were far higher than undoped ZnO. The anti-microbial activities were also higher than the standard controls which proves the prepared material to act dually both as a photocatalytic and anti-microbial agent.

Transition‐Metal‐Doped α‐MnO2 Nanorods as Bifunctional Catalysts for Efficient Oxygen Reduction and Evolution Reactions

AbstractNano‐sized α‐MnO2 nanorods doped with Co or Ru were directly synthesized using a continuous hydrothermal synthesis process (production rate 10 g h−1) and investigated as relatively inexpensive (due to the small Ru content) bifunctional catalysts for both the Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER). The materials were extensively characterized using a range of analytical methods; these including Extended X‐Ray Absorption Fine Structure (EXAFS) spectroscopy measurements, which was accompanied by density functional theory studies, in order to elucidate the role of dopants in α‐MnO2 structure. Electrochemical ORR and OER investigations of the as‐prepared doped α‐MnO2 nanomaterials were compared to more expensive Pt/C or RuO2 catalysts. The doped manganese oxide nanomaterials were used as bifunctional catalysts in the positive electrode of zinc air batteries (with oversized zinc metal negative electrode and limited density of discharge window) and displayed excellent performance (the overpotential was 0.77 and 0.68 V for α‐MnO2 modified with 7.6 at% Co and 9.4 at% Ru, respectively). Overall, as a result of doping, this study achieved improved bifunctional catalytic activities of metal oxide catalysts, which was comparable to more expensive alternatives.

Preparation and Catalytic Performance of Fe3+ Doped Nano-materials

Fe3+-doped nano-TiO2 powders were prepared by sol-gel method. The photocatalytic activity of Fe3+-doped TiO2 nanoparticles was studied by using UV lamp as light source and methylene blue as degradation target. The photocatalytic activity of Fe3+-doped TiO2 was studied by degradation of 4L methylene blue solution with initial concentration of 10mg · L - 1. The results show that the photocatalytic activity of TiO2 can be improved by the addition of Fe3+. When the molar ratio of Fe3+ is 0.5-1%, the calcination temperature is 500 ℃. The photocatalytic degradation of methylene blue is the best.