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The solar-irradiation-induced photothermal effect can accelerate the sluggish kinetics during water oxidation. However, the mechanism describing the photothermal effect is not clear and the range of suitable materials is not well developed, limiting the design and applicability of this technique. Herein, taking a series of (Co1-xNix)3C (x = 0, 0.1, and 0.2) oxygen evolution reaction (OER) catalysts as model catalysts, the catalytic mechanism of the interfacial photothermal effect (IPE) via concentrated solar irradiation (CSI) is comprehensively uncovered. The temperature/solar irradiation dependence of the polarized cyclic voltammetry (CV) data proves that the chemical basis of the photothermal effects of the catalysts mainly involves enhanced OH- filling at the interface between the catalyst and electrolyte. Hall tests at variable temperatures illustrate that the physical basis for OER enhancement by CSI is that alloyed Ni can cause conversion of the carriers from electrons to holes in Co3C, leading to enhanced conductivity and light absorption and heat conversion abilities. As a result, (Co0.8Ni0.2)3C exhibits a 660.3% OER enhancement and requires only a 262 mV overpotential to produce a current density of 10 mA cm-2 under CSI, making it superior to most reported OER catalysts. Also, for the hydrogen evolution reaction (HER), (Co0.8Ni0.2)3C requires only 69 mV to drive a current density of 10 mA cm-2 under CSI conditions. Finally, this work gives insight into the roots of the photothermal enhancement of OER activity. [ABSTRACT FROM AUTHOR]

A special core/shell/shell structured NaYF4/NaYF4:Yb3+,Er3+/NaYF4 (CSS) nanocrystal was designed to ensure each luminescence center in the emitting shell had the same surroundings. The nanocrystal includes a support core NaYF4 nanoparticle in the center coated by a thin emitting shell NaYF4:Yb3+,Er3+ and another NaYF4 shell with adjustable thickness as the outer shielding shell. The green upconversion fluorescence intensity Ig(d) of the CSS nanoparticles shows an exponential relationship with the thickness d of the shielding shell. When d decreased to 0, Ig(0) was ~356 times smaller than Ig(∞) due to the drastic fluorescence quenching of the rare earth luminescence centers by the surroundings. Our experimental results indicate that ~90% of the severe effect of the surroundings can be eliminated by coating with a ~4 nm-thick NaYF4 shielding shell. [ABSTRACT FROM AUTHOR]

Bismuth phosphate represents one promising class of luminescent host materials, while its application is challenged by structural instability. In this work, a series of nanocrystals Bi1-xLnxPO4 (x = 0.02--0.09; Ln = La, Ce, Nd, Eu, Er) were prepared with an aim to find new routes in improving the structural stability of BiPO4 nanocrystals. Systematic sample characterization by XRD, SEM, TEM, and EDX indicates that doping a small amount of Ln3+ ions ≤9% could significantly stabilize the low temperature monoclinic phase (LTMP) by retarding the structure transition to the high temperature monoclinic phase (HTMP). For instance, after annealing at 900 °C, the relative contents of LTMP for co-doping of 5% La3+, 5% Nd3+, 5% Ce3+ with 2% Eu3+ were as high as 89%, 87%, and 96%, respectively, which are totally different from the un-doped BiPO4 at this temperature where LTMP is absent completely. This phenomenon has never been reported before for improving the stability of BiPO4, which has been explained in terms of lattice disorder due to the preference of the linking ways of rare earth-oxygen polyhedra and PO4 tetrahedra. With this abnormal structural stabilization, the luminescent properties of the Ln3+ doped LTMP, including emission intensity, lifetime, and quantum efficiency, were further tailored through simply tuning the calcination temperatures. [ABSTRACT FROM AUTHOR]

In this paper, the decrease of fill factor with increase of light illumination intensity was investigated through light assisted impedance studies based on ITO/poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate)/[poly(3-hexylthiophene):1-(3-methyloxycarbonyl)-propyl-1-phenyl(6,6)C61 (P3HT:PCBM)]/Ca/Al solar cells. It was found that the charge accumulation at the electrode interface causes a decrease in parallel resistance (Rp), consequently a reduction in fill factor. Moreover, it has also been found that the photocurrent loss near the open-circuit voltage through bimolecular recombination also leads to the reduction of fill factor with increasing light intensity in P3HT:PCBM solar cells. [ABSTRACT FROM AUTHOR]

Self-assembly Zn/ZnO composite nanowires were successfully synthesized viaa simple chemical vapor deposition method. The composition and crystal structure of the Zn/ZnO composite nanowires were characterized by transmission electron microscopy. The surface of the ZnO nanowires was decorated with Zn nanoparticles. Their photoluminescence properties were measured, indicating that the near-band edge emission intensity was significantly enhanced and visible emission was suppressed, which originates from the coupling between surface plasmons and the near-band edge emission of ZnO (or electromagnetic field). Random lasing from Zn/ZnO composite nanowires was observed due to the surface plasmon resonant effect. Our results show a convenient way to achieve laser action by the surface plasmon resonant effect. [ABSTRACT FROM AUTHOR]

Controlled synthesis of Al3+doped ZnO hexagonal nanoplates was achieved viaa facile one-step hydrothermal approach. The thicknesses of nanoplates, ranging from about 60 nm to 200 nm, can be controlled by variation of Al3+concentration. A possible mechanism was proposed for the growth of a ZnO nanoplate and Al3+cations played a crucial role for the shape-controlled synthesis. The photoluminescence spectra clearly showed a blue shift with the increasing Al3+content. [ABSTRACT FROM AUTHOR]

Hierarchical In2O3(ZnO)10superlattice nanostructures were controllably synthesized in high yield by a simple chemical vapor deposition method, at low temperature. Scanning electron microscopy and transmission electron microscopy observations showed that In2O3(ZnO)10superlattice platelets regularly arrayed along axial In2O3(ZnO)10superlattice nanowires. High-resolution transmission electron microscopy results demonstrated that the two adjacent In–O layers sandwich eleven layered wurtzite In/Zn–O layers. X-Ray diffraction data for In2O3(ZnO)10were obtained to fill the gap in the JCPDS database. A possible growth mechanism is suggested in terms of the Stranski–Krastanow growth mode of semiconductor quantum dots. Low-temperature synthesis of hierarchical In2O3(ZnO)10superlattice nanostructures is an important step toward fabricating highly densely integrated functional nanodevices. [ABSTRACT FROM AUTHOR]

We report on a cavity mode mapping of ZnO tapered nanowires using micro-photoluminescence spectroscopy at room temperature. Both the Fabry-Perot (FP) and the whispering gallery (WG) modes are identified in a single wire. The emission spectra from single nanowires comprise regular Lorentzian peaks, which arise from the FP interference between the ends of the nanowire. The overall intensity along the tapered wire varies periodically. This variation is ascribed to WG mode resonances across the nanowire. The results agree well with the theoretical calculations using the finite-difference time-domain method. [ABSTRACT FROM AUTHOR]

Single-crystalline KNbO3nanorods were prepared from Nb2O5by hydrothermal synthesis at 180 °C in a KOH solution using sodium dodecyl sulfate surfactant. The morphology of the KNbO3product was strongly influenced by the addition of the surfactant, the concentration of the reactants, the reaction time and temperature, demonstrating that KN nanorods were only obtained in a narrow window of synthesis parameters. At the optimized conditions the orthorhombic KNbO3nanorods were 100–300 nm in diameter, up to 5 µm in length and grew along the [001] direction. The proposed growth mechanism is based on self-assembly of cube-shaped or facetted KNbO3nanocrystals into mesocrystals, which further ripen into nanorods. High temperature X-ray diffraction, calorimetry and Raman spectroscopy evidenced that the orthorhombic to tetragonal and tetragonal to cubic phase transition of KNbO3nanorods occurred at significantly lower temperatures than for bulk KNbO3, reflecting finite size or disorder effects. [ABSTRACT FROM AUTHOR]

Indium-doped ZnO nanospirals were synthesized by one-step thermal evaporation. Transmission electron micrographs show that the nanospirals are structurally uniform and free of defects. The helical nanostructures, which are constructed by rolling nanobelts grown along the [formula] direction with the ±(0001) polar planes as the dominate surfaces, are energetically favored in terms of the electrostatic polar charge model. The typical radius of curvature of the nanospirals is several micrometers. The In-doped nanospirals are expected to have interesting optoelectronic and mechanical properties and could be potential building blocks in nanoscale optoelectronic and electromechanical systems. [ABSTRACT FROM AUTHOR]

The growth of highly oriented (110) γ-CuI films on copper substrates with the best photoluminescence properties among all known CuI films are demonstrated, in the context of improving the current techniques in the preparation of CuI films for electronic and optoelectronic applications. The comparison of the photoluminescence spectra of CuI films with different growth orientations shows that the highly oriented (110) films prepared are less defective and give only a sharp exciton band. [ABSTRACT FROM AUTHOR]

It is generally accepted that the nonlinear I–V characteristics for semiconductor nanostructures are mainly induced by the Schottky contacts or by the space charge limited transport mechanism. We perform I–V measurements on undoped and doped In–Zn–O compound nanobelts and confirm that their intrinsic non-ohmic transport behaviors are not caused by these mechanisms. A model based on the hopping assisted trap state electrons transport process is introduced to explain the nonlinear I–V characteristics and to extract their electrical parameters. An understanding of this trap-state influenced carrier transport can advance the progress of nanomaterials applications and enable us to distinguish their intrinsic transport behaviors from contact effects. The results also indicate that the material has good electrical properties and can be used as a potential substitute for In2O3. [ABSTRACT FROM AUTHOR]

Highly aligned nanowire bundles were controllably fabricated through the reaction of Si with oxygen, using molten Ga and Au as catalysts. Scanning electron microscopy reveals that the bundles have the ability to self-assemble into various morphologies, a few of which, including one that strikingly resembles a sunflower, were not reported before. Examinations of the bundles by transmission electron microscopy show that they contain fine, amorphous SiOx nanowires, with x ranging from 1.2 to 1.5. In the sunflower-like morphology, highly packed bundles form the disc florets and loosely packed bundles around the rim of the disc form the ray florets. We have studied the conditions under which the sunflower-like morphology could be obtained and suggest a possible mechanism for its growth. Room-temperature cathodoluminescence spectra of the nanowire bundles show that they emit an intense broad-band light covering the entire visible range. [ABSTRACT FROM AUTHOR]