Uniform Decoration Research Articles

Designing CuOx Nanoparticle-Decorated CeO2 Nanocubes for Catalytic Soot Oxidation: Role of the Nanointerface in the Catalytic Performance of Heterostructured Nanomaterials

This work investigates the structure-activity properties of CuOx-decorated CeO2 nanocubes with a meticulous scrutiny on the role of the CuOx/CeO2 nanointerface in the catalytic oxidation of diesel soot, a critical environmental problem all over the world. For this, a systematic characterization of the materials has been undertaken using transmission electron microscopy (TEM), transmission electron microscopy-energy-dispersive X-ray spectroscopy (TEM-EDS), high-angle annular dark-field-scanning transmission electron microscopy (HAADF-STEM), scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS), X-ray diffraction (XRD), Raman, N2 adsorption-desorption, and X-ray photoelectron spectroscopy (XPS) techniques. The TEM images show the formation of nanosized CeO2 cubes (∼25 nm) and CuOx nanoparticles (∼8.5 nm). The TEM-EDS elemental mapping images reveal the uniform decoration of CuOx nanoparticles on CeO2 nanocubes. The XPS and Raman studies show that the decoration of CuOx on CeO2 nanocubes leads to improved structural defects, such as higher concentrations of Ce(3+) ions and abundant oxygen vacancies. It was found that CuOx-decorated CeO2 nanocubes efficiently catalyze soot oxidation at a much lower temperature (T50 = 646 K, temperature at which 50% soot conversion is achieved) compared to that of pristine CeO2 nanocubes (T50 = 725 K) under tight contact conditions. Similarly, a huge 91 K difference in the T50 values of CuOx/CeO2 (T50 = 744 K) and pristine CeO2 (T50 = 835 K) was found in the loose-contact soot oxidation studies. The superior catalytic performance of CuOx-decorated CeO2 nanocubes is mainly attributed to the improved redox efficiency of CeO2 at the nanointerface sites of CuOx-CeO2, as evidenced by Ce M5,4 EELS analysis, supported by XRD, Raman, and XPS studies, a clear proof for the role of nanointerfaces in the performance of heterostructured nanocatalysts.

Cu2O Nanowire Photocathodes for Efficient and Durable Solar Water Splitting.

Due to its abundance, scalability, and nontoxicity, Cu2O has attracted extensive attention toward solar energy conversion, and it is the best performing metal oxide material. Until now, the high efficiency devices are all planar in structure, and their photocurrent densities still fall well below the theoretical value of 14.5 mA cm(-2) due to the incompatible light absorption and charge carrier diffusion lengths. Nanowire structures have been considered as a rational and promising approach to solve this issue, but due to various challenges, performance improvements through the use of nanowires have rarely been achieved. In this work, we develop a new synthetic method to grow Cu2O nanowire arrays on conductive fluorine-doped tin oxide substrates with well-controlled phase and excellent electronic and photonic properties. Also, we introduce an innovative blocking layer strategy to enable high performance. Further, through material engineering by combining a conformal nanoscale p-n junction, durable protective overlayer, and uniform catalyst decoration, we have successfully fabricated Cu2O nanowire array photocathodes for hydrogen generation from solar water splitting delivering unprecedentedly high photocurrent densities of 10 mA cm(-2) and stable operation beyond 50 h, establishing a new benchmark for metal oxide based photoelectrodes.

Improving antifouling ability by site-specific silver decoration on polyethylene ionomer membranes for water remediation: assessed using 3D micro computed tomography, water flux and antibacterial studies

Silver laden ionomeric membranes for efficient water purification.

Effect of Uniform Decoration of Ag2S Nanoparticles on Physical Properties of Granular TiO2 Thin Films Synthesized by Using Spin Coating Technique

Effect of Uniform Decoration of Ag2S Nanoparticles on Physical Properties of Granular TiO2 Thin Films Synthesized by Using Spin Coating Technique

One-pot hydrothermal synthesis of graphene–RuO2–TiO2 nanocomposites

A porous ternary nanocomposite based on graphene, RuO2 and TiO2 has been prepared via a facile in-situ co-assembly without any surfactants. A unique morphology of highly-curled graphene sheets loaded with sporadic spots or coatings comprised of mixed RuO2 and TiO2 nanodots was achieved for the first time. This uniform decoration indicates strong interaction between graphene and the as-grown nanoparticles favoring the full separation of graphene sheets. The formation mechanism of such a porous but tightly bonded hetero-nanostructure benefiting from linking effect of TiO2 is proposed. Electrochemical tests showed a characteristic capacitive behavior and the specific capacitance values of 216.7–396.5F/g depending on the ratios of Ru/Ti, which has potential for energy storage.

Effective photocatalytic efficacy of hydrothermally synthesized silver phosphate decorated titanium dioxide nanocomposite fibers

Hierarchical Ag3PO4/TiO2 nanocomposite fibers were prepared by combining electrospinning technique and hydro-thermal growth method. As-synthesized samples were characterized by using field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Photoluminescence (PL), and Fourier transform infra-red (FT-IR) spectroscopy. The FE-SEM image revealed a uniform decoration of Ag3PO4 nanoparticles without aggregation on primary TiO2 nanofibers. The photocatalytic and antibacterial studies were performed and results were shown that the Ag3PO4/TiO2 nanocomposite fibers show an enhanced photocatalytic and antibacterial activity toward the degradation of dye methylene blue and bacteria (Escherichia coli, Staphylococcus aureus) respectively. Our results can provide new insights of Ag3PO4/TiO2 nanocomposite fibers for the potential applications in antibacterial and waste water treatment.

Liquid‐Crystal‐Mediated Self‐Assembly of Porous α‐Fe2O3 Nanorods on PEDOT:PSS‐Functionalized Graphene as a Flexible Ternary Architecture for Capacitive Energy Storage

A novel aqueous‐based self‐assembly approach to a composite of iron oxide nanorods on conductive‐polymer (CP)‐functionalized, ultralarge graphene oxide (GO) liquid crystals (LCs) is demonstrated here for the fabrication of a flexible hybrid material for charge capacitive application. Uniform decoration of α‐Fe2O3 nanorods on a poly(3,4‐ethylene‐dioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)‐functionalized, ultralarge GO scaffold results in a 3D interconnected layer‐by‐layer (LBL) architecture. This advanced interpenetrating network of ternary components is lightweight, foldable, and possesses highly conductive pathways for facile ion transportation and charge storage, making it promising for high‐performance energy‐storage applications. Having such structural merits and good synergistic effects, the flexible architecture exhibits a high specific discharge capacitance of 875 F g−1 and excellent volumetric specific capacitance of 868 F cm−3 at 5 mV s−1, as well as a promising energy density of 118 W h kg−1 (at 0.5 A g−1) and promising cyclability, with capacity retention of 100% after 5000 charge–discharge (CD) cycles. This synthesis method provides a simple, yet efficient approach for the solution‐processed LBL insertion of the hematite nanorods (HNR) into CP‐functionalized novel composite structure. It provides great promise for the fabrication of a variety of metal‐oxide (MO)‐nanomaterial‐based binder and current collector‐free flexible composite electrodes for high‐performance energy‐storage applications.

Nanostructured zirconia decorated reduced graphene oxide based efficient biosensing platform for non-invasive oral cancer detection

We report results of the studies relating to fabrication of a non-invasive, label-free and an efficient biosensing platform for detection of the oral cancer biomarker (CYFRA-21-1). One step hydrothermal process was used for uniform decoration of nanostructured zirconia (average particle size 13nm) on reduced graphene oxide (ZrO2–RGO) to avoid coagulation of the zirconia nanoparticles and to obtain enhanced electrochemical performance of ZrO2–RGO nanocomposite based biosensor. Further, ZrO2–RGO has been functionalized using 3-aminopropyl triethoxy saline (APTES) and electrophoretically deposited on the indium tin oxide coated glass substrate at a low DC potential.The APTES/ZrO2–RGO/ITO electrode exhibits improved heterogeneous electron transfer (more than two times) with respect to that of the APTES/ZrO2/ITO electrode indicating faster electron transfer kinetics. The –NH2 containing APTES/ZrO2–RGO/ITO platform is further biofunctionalized with anti-CYFRA-21-1. The structural and morphological investigations of the ZrO2–RGO based biosensing platform have been accomplished using X-ray diffraction (XRD), electrochemical, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) studies. This immunosensor exhibits a wider linear detection range (2–22ngmL−1), excellent sensitivity (0.756µAmLng−1) and a remarkable lower detection limit of 0.122ngmL−1. The observed results have been validated via enzyme linked immunosorbent assay (ELISA).

Uniform decoration of silver nanoparticle on exfoliated graphene oxide sheets and its ammonia gas detection

Silver nanoparticles (AgNP) decorated graphene oxide (GO) sheets were prepared by reducing AgNO3 with vitamin C in the presence of GO. Different molar concentration of AgNO3 played a significant role in the size of AgNP in GO. The synthesized AgNP–GO composites were characterized by powder X-ray diffraction, scanning electron microscopy, ultraviolet–visible–near infrared, Fourier transform infrared and micro Raman spectroscopy techniques. We demonstrated the fiber optic gas sensor using reduced graphene oxide (rGO) and AgNP–GO composites for 0–500ppm ammonia vapor concentrations at 27°C. Sensitivities of rGO, 0.1M AgNP–GO and 0.6M AgNP–GO composites coated fiber optic sensors were calculated as −0.08, −0.177, −0.12counts/ppm respectively. The agglomeration of AgNP at 0.6M concentration along with increased particle size significantly decreased the sensing performance.

ZnO decorated TiO2 nanosheet composites for lithium ion battery

This work reports on successful fabrication of TiO2@ZnO arrays nanocomposites for lithium ion battery application without any polymeric binder and conductive additives. The sandwich-like TiO2@ZnO framework with 3D interconnected construction shows stable cycling performance with a specific capacity of 340.2mAhg−1 at a current density of 200mAg−1 after 100 cycles, which possesses more competitive cycling performance than the bare ZnO arrays. It is noted that the uniform decoration of ZnO nanoparticles onto the TiO2 nanosheet arrays plays a significant role in advancing their electrochemical performance. The volume change and aggregation of ZnO nanoparticles can be efficiently mitigated with the support of TiO2 nanosheet cushions. Interestingly, the TiO2@ZnO array can be an ideal electrode for flexible electronics.

3D Woven-Like Carbon Micropattern Decorated with Silicon Nanoparticles for Use in Lithium-Ion Batteries.

Carbon/silicon composite materials are a promising anode substrate for use in lithium-ion batteries. In this study, we suggest a new architecture for a composite electrode made of a woven-like carbon material decorated with silicon nanoparticles. The 3D woven-like carbon (WLC) structure was fabricated using direct carbonization of multi-beam interference lithography polymer patterns. Subsequent solution coating was applied to decorate the WLC with silicon nanoparticles (SiNPs). The SiNP/WLC electrode exhibited a specific capacity of 930 mAh g(-1) , which is three times higher than the specific capacity of the bare electrode. Specifically, the SiNP/WLC electrode exhibited an outstanding retention capacity of 81 % after 50 cycles and a Coulombic efficiency of more than 98 %. This rate capability performance was attributed to the WLC structure and the uniform decoration of the SiNPs.

Surface decoration of MoSI nanowires and MoS2 multi-wall nanotubes and platinum nanoparticle encapsulation

Here we report on decoration of MoS2 nanotubes with platinum nanoparticles and partial encapsulation of platinum during the transformation of decorated Mo6SyIz (8.2<y+z<10) nanowires into MoS2 nanotubes. The proposed method enables direct decoration of both nanotubes and nanowires directly from aqueous solution of Na2PtCl4 at room temperature without reducing agents. A stable and uniform decoration is observed with average particle diameters of around 2nm and a controllable surface density, covering up to 80% of the nanowire surface. Sulphurisation of decorated nanowires was performed, during which platinum nanoparticles aggregated into larger formations, and partial encapsulation of elongated platinum nanorods in the obtained multi-wall MoS2 nanotubes is observed.

Fluorine-Doped SnO2@Graphene Porous Composite for High Capacity Lithium-Ion Batteries

For the first time, a composite of fluorine-doped SnO2 and reduced graphene oxide (F-SnO2@RGO) was synthesized using a cheap F-containing Sn source, Sn(BF4)2, through a hydrothermal process. X-ray photoelectron spectroscopy and X-ray diffraction results identified that F was doped in the unit cells of the SnO2 nanocrystals, instead of only on the surfaces of the nanoparticles. F doping of SnO2 led to more uniform and higher loading of the F-SnO2 nanoparticles on the surfaces of RGO sheets, as well as enhanced electron transportation and Li ion diffusion in the composite. As a result, the F-SnO2@RGO composite exhibited a remarkably high specific capacity (1277 mA h g–1 after 100 cycles), a long-term cycling stability, and excellent high-rate capacity at large charge/discharge current densities as anode material for lithium ion batteries. The outstanding performance of the F-SnO2@RGO composite electrode could be ascribed to the combined features of the composite electrode that dealt with both the electrode dynamics (enhanced electron transportation and Li ion diffusion due to F doping) and the electrode structure (uniform decoration of the F-SnO2 nanoparticles on the surfaces of RGO sheets and the three-dimensional porous structures of the F-SnO2@RGO composite).

Novel fungus-Fe3O4 bio-nanocomposites as high performance adsorbents for the removal of radionuclides

The bio-nanocomposites of fungus-Fe3O4 were successfully synthesized using a low-cost self-assembly technique. SEM images showed uniform decoration of nano-Fe3O4 particles on fungus surface. The FTIR analysis indicated that nano-Fe3O4 was combined to the fungus surface by chemical bonds. The sorption ability of fungus-Fe3O4 toward Sr(II), Th(IV) and U(VI) was evaluated by batch techniques. Radionuclide sorption on fungus-Fe3O4 was independent of ionic strength, indicating that inner-sphere surface complexion dominated their sorption. XPS analysis indicated that the inner-sphere radionuclide complexes were formed by mainly bonding with oxygen-containing functional groups (i.e., alcohol, acetal and carboxyl) of fungus-Fe3O4. The maximum sorption capacities of fungus-Fe3O4 calculated from Langmuir isotherm model were 100.9, 223.9 and 280.8mg/g for Sr(II) and U(VI) at pH 5.0, and Th(IV) at pH 3.0, respectively, at 303K. Fungus-Fe3O4 also exhibited excellent regeneration performance for the preconcentration of radionuclides. The calculated thermodynamic parameters showed that the sorption of radionuclides on fungus-Fe3O4 was a spontaneous and endothermic process. The findings herein highlight the novel synthesis method of fungus-Fe3O4 and its high sorption ability for radionuclides.

Sulfur-doped graphene-supported Ag nanoparticles for nonenzymatic hydrogen peroxide detection

Heteroatom doping is an effective way to modulate the physicochemical properties of graphene and its hybrid materials. In this work, sulfur-doped graphene (SG) was used for the first time as a supporting material for loading Ag nanoparticles, and the resulting Ag/SG hybrid with a high S-doping level (2.8 at.%) and a uniform Ag NP decoration was successfully prepared by a microwave-assisted method. Electrochemical measurements revealed that the Ag/SG exhibited a better electrocatalytic activity toward H2O2 reduction than undoped Ag/reduced graphene oxide, which highlighted the important role of S-doping that could not only improve the charge transfer, but also introduce more defects as active sites. The nonenzymatic sensor based on Ag/SG displayed good sensing performances for highly sensitive, selective, and stable detection of H2O2, demonstrating that SG is indeed a promising catalyst-supporting material for electrochemical sensing.

Noble metals supported on carbon nanotubes using supercritical fluids for the preparation of composite materials: A look at the interface

Carbon nanotubes (CNTs) have attracted great interest from scientific and industrial communities thanks to their remarkable properties. However, even if their mass production is nowadays well-known, the methods commonly used lead to bundles made of hundreds of single nanotubes with inert surface. Through the description of a simple, rapid and green procedure to uniformly decorate CNTs with metal nanoparticles (Ag, Pd), this paper presents a look at the CNTs-metal interface as a function of the functionalization technique.Three types of CNTs are considered for deposition: raw CNTs, CNTs functionalized with the reference HNO3/H2SO4 method and CNTs functionalized with our approach using CO2/EtOH/H2O/H2O2 under temperature and pressure. For functionalized CNTs the Pd atoms and CNTs are linked by oxygen atoms and the coating is made of metallic palladium nanoparticles while palladium oxide nanoparticles are formed on raw CNTs, the functionalization having an influence on the nucleation and growth phenomenon. Furthermore the surface treatment of CNTs in acidic solution has a major drawback with CNTs contamination that is why a functionalization with CO2/EtOH/H2O/H2O2 under temperature and pressure is preferred. In addition, electron tomography has shown that the use of supercritical fluids leads to a uniform deposition of metal inside the bundles of CNTs. The orientation relationship between palladium nanoparticles and CNTs has also been determined; the {111} planes of palladium nanoparticles are parallel to the CNTs graphite planes. The supercritical fluids chemical deposition method appears as an interesting alternative process for the uniform decoration of CNTs with strong interfaces for the preparation of composite materials.

Controllable construction of Titanium dioxide-Zirconium dioxide@Zinc hydroxyfluoride networks in micro-capillaries for bio-analysis

Glass/silica-based flow channels are widely used in capillary electrophoresis and micro-total analysis systems. However, it is almost impossible to achieve controllable fabrication of microstructures with enhanced mixing performance for high-efficiency bio-analysis in confined micro-channels. Here, various morphologies were controllably achieved by tuning the molar ratio of the reaction agents in a confined microchannel. Fluid flow simulation is demonstrated to investigate the structure stability and mixing performance. Multifunctional networks with uniform and deep decoration are fabricated in confined micro-capillaries, owing to the enhanced mixing performance. The modified micro-capillaries exhibit high efficiencies for the selective enrichment of phosphopeptides from traditional model samples. Furthermore, the fabricated micro-capillaries also exhibited high performance in practical applications (for selective enrichments from bovine milk and cancer serum). These outstanding features make the microstructure-modified micro-capillaries promising for bio-analysis.

Pollutant capturing SERS substrate: porous boron nitride microfibers with uniform silver nanoparticle decoration.

How to concentrate target molecules on the surface of a SERS substrate is a key problem in the practical application of SERS. Herein, we designed for the first time a pollutant capturing surface enhanced Raman spectroscopy (SERS) substrate, namely porous BN microfibers uniformly decorated with Ag nanoparticles, in which the BN microfibers adsorb pollutants, while the Ag nanoparticles provide SERS activity. This SERS substrate captures pollutants from an aqueous solution completely and accumulates them all on its surface without introducing noise signals. The pores of BN protect the silver particles from aggregation which makes BN/Ag a stable and recyclable SERS substrate. What's more, while the dyes are thoroughly concentrated from a diluted solution, the SERS detection limit is easily enhanced, from 10(-6) M to 10(-9) M.

Uniform decoration of Pt nanoparticles on well-defined CdSe tetrapods and the effect of their Pt cluster size on photocatalytic H2generation

Direct decoration of Pt nanoparticles onto CdSe tetrapods with controlled sizes and their photocatalytic H2generation efficiency.

Nano-functionalized filamentous fungus hyphae with fast reversible macroscopic assembly & disassembly features.

A uniform decoration of hyphae by polyaniline nanoparticles (PANI NPs) was achieved here. This novel hybrid structure can be effectively assembled into a film by filtration and disassembled in water by shaking. This reversible process is very fast, which promises applications in nanomaterials including adsorption.