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For heterogeneous catalysts, the active sites exposed on the surface have been investigated intensively, yet the effect of the subsurface-underlying atoms is much less scrutinized. Here, a surface-engineering strategy to dope Ru into the subsurface/surface of Co matrix is reported, which alters the electronic structure and lattice strain of the catalyst surface. Using hydrogen evolution (HER) as a model reaction, it is found that the subsurface doping Ru can optimize the hydrogen adsorption energy and improve the catalytic performance, with overpotentials of 28 and 45 mV at 10 mA cm

Multicomponent nanocomposite colloidal spheres were synthesized with NaYF4:Yb,Er upconversion nanoparticle and CdSe quantum dots for tailoring visible emission. The CdSe/NaYF4:Yb,Er colloidal spheres were synthesized by improved emulsion-based self-assembly approach. They are well-dispersed in the colloidal sphere by electron diffraction X-ray mapping patterns. The colloidal spheres exhibited near-infrared photoresponse property. The intensity of short-wavelength emission at 408 nm was drastically weakened, and a red emission at 655 nm is substantially increased. Both the mechanism and multi-photon process of upconversion photoresponse was determined. It offers facile strategy to assemble multicomponent nanocomposite colloidal spheres for tuning visible emission.

In this paper, uniform NaGdF4:Yb3+, Er3+ nanorods doped with Fe3+ were synthesized by a facile hydrothermal method. The prepared NaGdF4:Yb3+, Er3+ doped with Fe3+ displayed hexagonal phase structure from XRD pattern and uniform nanorods with narrow size distribution from TEM. The signal of Fe3+ is accompanied with the Yb3+ and Er3+ from EDX line-scanning, which was confirmed that Fe3+ was doped successfully. The NaGdF4:Yb3+, Er3+ nanorods doped with Fe3+ show absorption of near-infrared region from UV–Vis absorption spectra. The upconversion luminescence intensity enhances with increasing content of Fe3+ under 980 nm excitation. When stoichiometric ratio of Fe3+ is 20 mol%, the strongest upconversion emission intensity could be obtained. But the upconversion luminescence would become weak when the stoichiometric ratio of Fe3+ is above 20 mol%. Based on above analysis, it is inferred that there is energy conversion between Fe3+ and rare earth ions by the luminescence mechanism. In this work, it provides a facile method for preparation of NaGdF4:Yb3+, Er3+ nanorods, which displays improving upconversion luminescence by Fe3+ doping.

Herein, NaGdF4:Yb,Er nanoparticles were anchored on a Material of Institute Lavoisier (MIL-101). In the well-defined heterostructure, MIL-101/NaGdF4:Yb,Er, the absorption and fluorescence could be tuned, and the composite facilitated the separation of photogenerated electron–hole pairs. Moreover, the heterostructure displayed a higher photocurrent and better degradation ability for Rhodamine B that its individual components owing to its synergistic effect.

Interface engineering is promising but still challenging for developing highly efficient and stable non-noble-metal-based electrocatalysts for water splitting. Herein, partially phosphidated core@shell Co@Co-P nanoparticles encapsulated in bamboo-like N, P co-doped carbon nanotubes (denoted as Part-Ph Co@Co-P@NPCNTs) are prepared through a pyrolysis-oxidation-phosphidation strategy. In this structure, each Co nanoparticle is covered with a thin Co-P layer to form a special core@shell heterojunction interface, and the core@shell structure is further encapsulated by N, P co-doped CNTs that not only protect the Co from corrosion but also guarantee an effective and fast electron transfer on cobalt phosphide. As a bifunctional catalyst for both the hydrogen evolution reaction and oxygen evolution reaction, it exhibits an excellent activity for overall water splitting, and enables long-term operation without significant degradation. Density functional theory calculations demonstrate that the interface of the Co/Co2 P heterojunction could lower the values of ΔGH * (hydrogen adsorption) and ΔGB (water dissociation), which are negatively correlated to the j10 , because of the electronic structures of up-shifted d-band center. This study not only presents an efficient and stable electrocatalyst for overall water splitting but also provides a special route for the interface engineering of heterostructures.

Highly monodispersed core-shell structured NaGdF4:Yb,Er@SiO2@Eu(TTA)3Phen(2-Thenoyltrifluoroacetone (TTA), 1,10-Phenanthroline monohydrate (Phen)) nanospheres were synthesized via two-step process. These nanospheres with diameter of 13 nm were encapsulated in SiO2 shell via micro-emulsion preparation. The ligand-sensitized Eu complexes attached to the outer surface of SiO2. The green (542 nm) and red (610 nm) light were excited by NIR and UV illumination, respectively. Thus, tunable photoresponse was possible in the core-shell structured hybrid nanocomposites. Under upconversion process, 5-fold increase at 542 nm and a 14-fold increase at 660 nm could be achieved under 980 nm laser, respectively.

The well-defined lanthanide co-doped upconversion nanoparticles(UCNPs) had been synthesized using a simple solvothermal route at 150 °C, which was lower than previous reports. The shuttle-like and spherical UCNPs co-doped by Yb 3+ /Tm 3+ had been prepared, respectively. The morphology, crystal phase and size distribution of various UCNPs could be easily controlled. The growth mechanism and morphology transition of UCNPs had been deduced by schematic diagram. UC luminescence could be tuned by employing different host lattices (GdF 3 , YF 3 , NaGdF 4 and NaYF 4 ). NaGdF 4 :Yb 3+ /Tm 3+ displayed the strongest UC luminescence at 475 nm among four kinds of UCNPs, and its emission intensity was almost 10 times higher than that of NaYF 4 :Yb 3+ /Tm 3+ . UC mechanism had been determined by energy level diagrams. It’s revealed that the accumulation and energy transfer of Gd 3+ could be demonstrated in polycrystalline structure. The work provided a simple method for preparation of UCNPs with tunable UC luminescence.

The geometric size and distribution of magnetic nanoparticles are critical to the morphology of graphene (GN) nanocomposites, and thus they can affect the capacity and cycling performance when these composites are used as anode materials in lithium-ion batteries (LiBs). In this work, Fe3O4 nanorods were deposited onto fully extended nitrogen-doped GN sheets from a binary precursor in two steps, a hydrothermal process and an annealing process. This route effectively tuned the Fe3O4 nanorod size distribution and prevented their aggregation. The transformation of the binary precursor was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). XPS analysis indicated the presence of N-doped GN sheets, and that the magnetic nanocrystals were anchored and uniformly distributed on the surface of the flattened N-doped GN sheets. As a high performance anode material, the structure was beneficial for electron transport and exchange, resulting in a large reversible capacity of 929 mA·h·g–1, high-rate capability, improved cycling stability, and higher electrical conductivity. Not only does the result provide a strategy for extending GN composites for use as LiB anode materials, but it also offers a route for the preparation of other oxide nanorods from binary precursors.

In this article, we creatively incorporate naked Ag nanoparticles (nAgp), SiO2-covered Ag nanoparticles (SiAgp), and naked Ag nanoplates (nAgPl) into solution-processed tungsten oxide (WO3) hole transport layer in polymer solar cells (PSCs) to increase the light absorption through localized surface plasmon resonance (LSPR) effect. With optimized doping concentrations, nAgp decreases power conversion efficiency (PCE), however, SiAgp increases PCE by 13.2% and nAgPl increases PCE by 19.7%. In detail, the great PCEs discrepancies are mainly caused by the discrepancies of short circuit currents (J(sc)). The experiments results indicate that the naked surface of nAgp causes the exciton-quenching to decrease the J(sc) of PSCs. Whereas the capsulation of SiO2 at the surface of nAgp and the embedment of nAgPl in WO3 layer can prevent the exciton-quenching and help to use LSPR effect of Ag nano-dopants to enhance the J(sc) of PSCs. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.

MnO2 with urchin-like nano/micro hierarchical architecture was synthesized through an easy hydrothermal method at low temperature and used to prepare MnO2/graphene hybrid composite as electrode materials through an easy and efficient solution-based method. The MnO2 particles in the composite with 66.7% mass ratio could achieve specific capacitance as high as 451.5 F g(-1) at a scan rate of 10 mV s(-1) and exhibit good cycle stability with 93.8% capacitance retention over 2000 cycles. These properties result from the unique urchin-like nano/micro hierarchical structure of MnO2 as well as the function of graphene in enhancing the conductivity and utilization of MnO2.

The well-defined NaGdF4:Yb,Er nanorods (NRs) with various aspect ratios were synthesized using a facile hydrothermal method. The morphology and crystal phase of NRs could be controlled by reaction conditions. NaGdF4:Yb,Er NRs with various aspect ratios could be synthesized and their upconversion (UC) luminescence was tuned. It is displayed that the NRs with aspect ratios about 5 exhibited the strongest UC luminescence among samples. The growth mechanism and morphology transition of NRs had been deduced by schematic diagram. And UC mechanism had been determined by energy level diagrams. Compared with previous reports, the work provided a facial method for UCNRs with various aspect ratios at lower temperature.

Compared to conventional methods, a simple route is offered for synthesis of BaCO 3 with CO 2 and least energy consumption. And the morphology of BaCO 3 was tuned by controlling reaction conditions. The X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) were employed to characterize the products, the results showed that the products with various morphologies had the same crystal phase and growth direction. However, the distinct difference of the prepared products were determined by Raman and UV–vis spectra, showing shape-dependent optical properties. The results provide a useful model system for investigating the shape-dependent optical properties of carbonate nanocrystals.

The cubic PbS nanoflowers were successfully synthesized by the biomolecule-assisted method in the presence of supercritical carbon dioxide. This is an effective, simple and green synthetic method for the preparation of nanomaterials. It is noteworthy that the dosage of cetyltrimethylammonium bromide (CTAB) and chitosan as well as appropriate reaction time and pressure of system are crucial to form the unusual nanoflower structured PbS. The unique nanoflowers have numerous petals, which grow along the 〈100〉 direction as a single crystal. Especially, the nanoflower PbS indicates better sensitivity to the laser power via Raman spectra. Although the product size of PbS obtained is larger than the Bohr radius, its UV–vis absorption spectrum shows a remarkable blue-shift from that of bulk PbS due to quantum-confinement effects.

The nanostructured ZnS of cubic nanocorals and open-benzene ring has been synthesized by the biomolecule-assisted method in mixture of supercritical carbon dioxide and water as reaction medium at 150 °C and 28 MPa. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence spectrum of sample were characterized. The sodium tripoly phosphate and CO 2 as well as high-pressure condition might be the key factors for formation of the particular morphologies and nanostructures of ZnS. This synthesis method could be employed for preparation of other semiconductor nanomaterials.

The CaCO3/biopolymer composite materials have been prepared by a two-step synthesis. The biopolymer was synthesized from chitosan and acrylic acid in supercritical carbon dioxide, then a large scale of novel flowerlike structured calcite CaCO3 on the biopolymer has been synthesized for the first time by the following process of mineralization. The well-defined flowerlike morphology consisting of orderly and regular petals could be tailored by controlling the reaction time. The morphology evolution of CaCO3 was investigated by the XRD, FTIR and SEM. Moreover, the prepared CaCO3/biopolymer composite materials were further characterized by 1H NMR, HRTEM, SAED and XPS, respectively. The experimental results show that the petal possessed a single crystal structure and consisted of stackings of (18). Interestingly, the product is sensitive to the lower laser power by Raman spectra. Based on experimental results, the growth process of formation of a special shape for CaCO3 was also speculated, which indicates that acrylic acid and chitosan played an important role in forming substrates and in following further mineralization of CaCO3.