Photoelectrochemical Hydrogen Production of TiO₂ Passivated Pt/Si-Nanowire Composite Photocathode

Si nanowire (SiNW) arrays decorated with Pt nanoparticles are passivated with TiO₂ surface layer using atomic layer deposition (ALD). The sandwich structure TiO₂/Pt/SiNW shows superior photoelectrochemical performance to the control planar silicon electrodes, especially under the concentrated solar radiation. Pt nanoparticles separated from aqueous electrolyte by TiO₂ layer of more than 15 nm still well catalyze surface photoelectrochemical hydrogen production without direct contact to the electrolyte. This structural configuration shows remarkable chemical stability and anodically shifted onset potential, suggesting great promise for applications in solar hydrogen production. The maximum photon-to-energy conversion efficiency of the TiO₂/Pt/SiNW reaches 15.6%

Nanosize and Surface Charge Effects of Hydroxyapatite Nanoparticles on Red Blood Cell Suspensions

In this paper, the effects of size and surface charge of hydroxyapatite (HAP) particles on a red blood cell (RBC) suspension were studied. Results showed that the HAP particles exhibited nanosize and surface charge effects on the RBC suspension. Differing from HAP microparticles, HAP nanoparticles induced some aggregation of the RBCs in the unstructured agglutinates. HAP nanoparticles were adhered to the surface membrane of the RBCs due to their remarkably higher adsorption capacity than the HAP microparticles, resulting in the formation of a sunken appearance (“caves”) on the surface membrane of the RBCs without rupturing the lipid bilayer. In the case of high negatively charged HAP nanoparticles after heparin modification, the aggregation of the RBCs induced by the HAP nanoparticles was inhibited. Such HAP nanoparticle-induced aggregation of the RBCs could be attributed to the bridging force via the electrostatic interaction between the positively charged binding sites on the HAP surface and the negatively charged groups on the surface of the RBCs. The surface charge of the HAP nanoparticles is thus a crucial factor influencing the interaction between the HAP nanoparticles and the RBCs

Synthesis of Cerium Molybdate Hierarchical Architectures and Their Novel Photocatalytic and Adsorption Performances

Cerium molybdate (Ce–Mo) hierarchical architectures (such as the flowerlike, microspheric, and bundlelike structure) are successfully synthesized via a facile route with the assistance of amino acid (lysine, Lys). The influences of reaction parameters on the crystal structure and morphology of Ce–Mo hierarchical architectures are investigated. Samples obtained are characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), and thermogravimetric analysis (TGA). Furthermore, the photocatalytic and adsorption performances of samples obtained are investigated using different dyes, such as Cationic red X-GTL, Congo red, Methylene blue, Acid blue 80, and Methyl orange, as the model. The results show that Ce–Mo hierarchical architectures exhibit remarkably high efficiency to photocatalytically decompose Congo red under visible light irradiation, and significant adsorption performance on Cationic red X-GTL and Methylene blue. Contrarily, neither photocatalytic nor adsorption performance was observed on Methyl orange and Acid blue 80. Therefore, the as-synthesized Ce–Mo hierarchical architectures display promising potential for the removal of organic contaminants for environmental protection

Luminescence Enhanced Eu³⁺/Gd³⁺ Co-Doped Hydroxyapatite Nanocrystals as Imaging Agents In Vitro and In Vivo

Biocompatible, biodegradable, and luminescent nano material can be used as an alternative bioimaging agent for early cancer diagnosis, which is crucial to achieve successful treatment. Hydroxyapatite (HAP) nanocyrstals have good biocompatibility and biodegradability, and can be used as an excellent host for luminescent rare earth elements. In this study, based on the energy transfer from Gd³⁺ to Eu³⁺, the luminescence enhanced imaging agent of Eu/Gd codoping HAP (HAP:Eu/Gd) nanocrystals are obtained via coprecipitation with plate-like shape and no change in crystal phase composition. The luminescence can be much elevated (up to about 120%) with a nonlinear increase versus Gd doping content, which is due to the energy transfer (⁶P_J of Gd³⁺ → ⁵H_J of Eu³⁺) under 273 nm and the possible combination effect of the cooperative upconversion and the successive energy transfer under 394 nm, respectively. Results demonstrate that the biocompatible HAP:Eu/Gd nanocrystals can successfully perform cell labeling and in vivo imaging. The intracellular HAP:Eu/Gd nanocrystals display good biodegradability with a cumulative degradation of about 65% after 72 h. This biocompatible, biodegradable, and luminescence enhanced HAP:Eu/Gd nanocrystal has the potential to act as a fluorescent imaging agent in vitro and in vivo