We report that nanoscale carbon particles (carbon dots) upon simple surface passivation are strongly photoluminescent in both solution and the solid state. The luminescence emission of the carbon dots is stable against photobleaching, and there is no blinking effect. These strongly emissive carbon dots may find applications similar to or beyond those of their widely pursued silicon counterparts.

The supercritical fluid-processing technique, rapid expansion of a supercritical solution into a liquid solvent (RESOLV), was applied to the nanosizing of water-insoluble drug particles. Selected for demonstration were antiinflammatory drugs Ibuprofen and Naproxen, for which CO2 and CO2-cosolvent systems were used. The RESOLV process produces exclusively nanoscale (less than 100 nm) Ibuprofen and Naproxen particles suspended in aqueous solutions, and the aqueous suspensions of the drug nanoparticles are protected from particle agglomeration and precipitation by using common polymeric and oligomeric stabilization agents.

Nanoscale TiO 2 particles embedded in the hydrophilic cavities of Nafion membrane films were coated with silver for significantly improved photoconversion of CO 2 . The primary product from the photocatalytic reduction became methanol, with the overall conversion efficiency higher than that without the silver coating. These catalytic films are also stable chemically and photochemically, reusable in repeated reactions. The results from the characterization of the nanoparticles and the use of films with different silver loadings are presented and discussed.Metal-coated semiconductor nanoparticles have attracted much attention for various applications, especially in heterogeneous photocatalysis relevant to the solar energy conversion and environmental cleanup. 1-3 For example, noble metals such as silver, gold, copper, platinum, and palladium were deposited onto a TiO 2 surface for improved photocatalytic activities, 4,5 in particular with evaluations in the photochemical production of hydrogen and photoreductive conversion of CO 2 . 6-8 These composite photocatalysts have been based primarily on the metal coating of colloidal semiconductors. 9,10 However, a widely acknowledged issue with the colloidal particles is their significant aggregation in suspension, which not only reduces the active surface area but also compromises the desired photoreaction conditions due to severe light scattering effect of the aggregates. 10,11 Several strategies for addressing the issue have been explored in the preparation of photocatalysts based on metal-coated nanoscale semiconductors. 12-16 Anpo et al. hosted TiO 2 in zeolite cavities for subsequent platinum coating, 13 while Lianos et al. prepared TiO 2 nanoparticle films (y15 nm) on a glass substrate via the sol-gel method, followed by the photodeposition of silver nanoparticles (35-60 nm). 14 Separately, Wu et al. applied an improved sol-gel method to the preparation of nanoscale copper-loaded titania, in which the copper precursor was added during the hydrolysis and polycondensation. 16 These methods required high-temperature calcination to increase the crystallinity of the nanoparticles, which was generally accompanied by significant agglomeration of the nanoparticles. The agglomeration resulted in metal-coated catalyst particles of various sizes and shapes, but also negatively affected their photocatalytic activities. 17,18 We recently used commercially available perfluorinated ionomer membrane Nafion films, or more specifically the hydrophilic structural cavities in the membrane films, to host TiO 2 nanoparticles and demonstrated the superior performance of these optically transparent catalytic films in the photoreduction of CO 2 . 19 We have taken advantage of the homogeneous particle dispersion in the films to photochemically coat the TiO 2 nanoparticles with nanoscale silver.These films containing the silver-TiO 2 composite nanoparticles remained optically transparent, serving as improved photocatalysts for the CO 2 photoconversion.The procedure for the preparation of TiO...

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