Single crystalline anatase TiO(2) rods with dominant reactive {010} facets are directly synthesized by hydrothermally treating Cs(0.68)Ti(1.83)O(4)/H(0.68)Ti(1.83)O(4) particles. The nanosized rods show a comparable conversion efficiency in dye-sensitized solar cells (DSSCs), and a superior photocatalytic conversion of CO(2) into methane to the benchmark P25 TiO(2) nanocrystals.
This paper reports the synthesis of nanosized TiO 2 single crystals with different percentages of exposed (001) facets in the presence of HF solution. Various characterizations are conducted to understand the correlation between particle morphology, exposed (001) facets and photo-conversion effi ciency of the nanosized anatase TiO 2 single crystals. An enhancement in dye-sensitized solar cells (DSSCs) overall conversion effi ciency is observed for the photoanode consisting of nanosized TiO 2 single crystals with higher percentage of exposed (001) facets, increasing from 7.47%, 8.14% to 8.49% for the TiO 2 single crystals with ca. 10%, 38%, and 80% percentage of exposed (001) facets. Experimentally confi rmed by dark current potential and open-circuit voltage decay scans, such highly exposed (001) facets are not only favorable for more dye adsorption but also effectively retard the charge recombination process in DSSCs.
The dye-sensitized solar cell has been intensively investigated as a promising photovoltaic system in utilizing the clean and infinite solar energy due to its high efficiency, non-toxic, and low cost nature. Light scattering structures such as hollow spheres are proposed to increase the efficiency of DSSCs by improving light harvesting. This paper presents a facile one-pot synthesis method for a new type of shell-in-shell TiO 2 hollow spheres featuring excellent light scattering properties and its application in DSSCs. A 19% enhancement in DSSC efficiency is observed after introducing the shell-in-shell TiO 2 hollow spheres as a scattering layer in the solar cell.
Fluorescence diffuse optical tomography (FDOT) is an emerging biomedical imaging technique that can be used to localize and quantify deeply situated fluorescent molecules within tissues. However, the potential of this technique is currently limited by its poor spatial resolution. In this work, we demonstrate that the current resolution limit of FDOT can be breached by exploiting the nonlinear power-dependent optical emission property of upconverting nanoparticles doped with rare-earth elements. The rare-earth-doped core-shell nanoparticles, NaYF(4):Yb(3+)/Tm(3+)@NaYF(4) of hexagonal phase, are synthesized through a stoichiometric method, and optical characterization shows that the upconverting emission of the nanoparticles in tissues depends quadratically on the power of excitation. In addition, quantum-yield measurements of the emission from the synthesized nanoparticles are performed over a large range of excitation intensities, for both core and core-shell particles. The measurements show that the quantum yield of the 800 nm emission band of core-shell upconverting nanoparticles is 3.5% under an excitation intensity of 78 W/cm(2). The FDOT reconstruction experiments are carried out in a controlled environment using liquid tissue phantoms. The experiments show that the spatial resolution of the FDOT reconstruction images can be significantly improved by the use of the synthesized upconverting nanoparticles and break the current spatial resolution limits of FDOT images obtained from using conventional linear fluorophores as contrast agents.
Fluorescent nitrogen-enriched carbon nanodots (C-dots) of 1 to 3 nm were obtained through a one-pot reaction between melamine and glycerol. These C-dots show quantum yields up to 22% and a high two-photon absorption cross-section. The TiO 2 based photoanode sensitized by these C-dots is capable of converting near IR photon energy to photocurrent. The emergence of photoluminescent nanocarbons has attracted significant research interest in recent years, because carbon is cheap, abundant, chemically inert and biocompatible. Carbon nanodots (C-dots) are quasi-spherical particles of finite size, typically less than 5 nm, and comprise either amorphous or graphitic carbon. 1-3 Various works have demonstrated a promising application potential of C-dots in bioimaging, 2,4-7 optoelectronic devices 8 and photocatalysis. 9 A number of methods have been established to synthesize carbon nanodots, from 'top-down' approaches such as arc-discharge, 3 laser ablation, 2 and electrochemical exfoliation 10 to 'bottom-up' syntheses like carrier-supported resol carbonization, 6 dehydration of carbohydrates, 11 thermal oxidation, 12 microwaving 13 and 'hot injection' 14 of carbon precursors. The quantum yields (QYs) of these synthesized C-dots are generally low (typically under 15%). 2,6,13,15-19 While improving synthesis methods towards potential cost-effective mass production is a heated area, various studies have also attempted to unravel the photoluminescence mechanisms of C-dots. The luminescence origin was attributed to a surface trapping effect, 2 and other
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