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We presented the employment of ascorbic acid as the reducing agent for the in situ deposition of Ag nanoparticles on the surface of TiO2 nanotube arrays (TiO2 NTs/Ag). The structural investigation by scanning electron microscopy and transmission electron microscopy indicated that Ag nanoparticles with average diameters of 15 nm uniformly grew on TiO2 NTs walls. The possible formation mechanism of TiO2 NTs/Ag was proposed. UV–vis absorption and photoelectrochemical measurements indicated that the Ag sensitization extended the visible light absorption region, improved the photocurrent response, and enhanced solar-induced photoelectrocatalytic activities.

TiO2 nanotube arrays sensitized by copper nanoparticles (TiO2 NTs/Cu) exhibited highly efficient photoelectrocatalytic removal of RhB and Cr(VI). Vertically grown anatase TiO2 NTs on Ti substrates were prepared by electrochemical anodization followed by calcinations. Subsequently, Cu nanoparticles with uniform spherical structures and size distributions were deposited on TiO2 nanotubes by a modified hydrothermal reaction. By exploiting TiO2 NTs/Cu as both photoelectrodes and photocatalysts, high photocurrent density and photoelectrocatalytic removal efficiencies of RhB and Cr(VI) were achieved under solar light irradiation. The enhancement on the photoelectrochemical performance was explained by the optoelectronic coupling between Cu nanoparticles and TiO2 NTs, which accelerated the transfer rate of electrons, and subsequently decreased the electron/hole pair recombination.

Mn4+-activated fluoride compounds, emerging as highly efficient rare-earth-free red-emitting phosphors, have been regarded as excellent color converters for warm white-light-emitting diodes recently. In this paper, using a facile two-step co-precipitation approach, we report the synthesis and structure of a novel ZnTiF6·6H2O:Mn4+ red-emitting phosphor as well as its optical performance in detail. Particularly, the as-prepared yellowish ZnTiF6·6H2O:Mn4+ powders exhibit an intense narrow-band Mn4+ 2Eg → 4A2g red emission with internal quantum efficiency of 26.4% upon the excitation of blue light corresponding to 4A2g → 4T2g transitions of Mn4+. As a consequence, the warm white-light-emitting diodes with tunable correlated color temperature and color rendering index can be easily realized by combining ZnTiF6·6H2O:Mn4+ red phosphor with commercial YAG:Ce3+ yellow phosphor on the blue-InGaN chip.

TiO2 nanotube arrays sensitized with Sb2S3 microcrystalline were successfully fabricated by a two-step process of photodeposition method followed by annealing treatment. The structural investigation by X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that the Sb2S3 microparticles grew uniformly on the walls of TiO2 nanotubes. The amorphous Sb2S3 microspheres could be transformed into octahedral microcrystals after annealing treatment. The Sb2S3 modification of the TiO2 nanotube arrays resulted in an increase in visible light adsorption and photocatalytic activities toward degradation of methyl orange (MO) and rhodamine B (RhB) dyes under visible light irradiation.

Mn4+-activated fluoride compounds, emerging as highly efficient rare-earth-free red-emitting phosphors, have been regarded as excellent color converters for warm white-light-emitting diodes recently. In this paper, using a facile two-step co-precipitation approach, we report the synthesis and structure of a novel ZnTiF6·6H2O:Mn4+ red-emitting phosphor as well as its optical performance in detail. Particularly, the as-prepared yellowish ZnTiF6·6H2O:Mn4+ powders exhibit an intense narrow-band Mn4+ 2Eg → 4A2g red emission with internal quantum efficiency of 26.4% upon the excitation of blue light corresponding to 4A2g → 4T2g transitions of Mn4+. As a consequence, the warm white-light-emitting diodes with tunable correlated color temperature and color rendering index can be easily realized by combining ZnTiF6·6H2O:Mn4+ red phosphor with commercial YAG:Ce3+ yellow phosphor on the blue-InGaN chip.

Transparent bulk glass ceramic containing Cr3+:LiGa5O8 nanoparticles was fabricated as an alternative for monocrystal to explore the possible application in fluorescence lifetime-based temperature sensing. Such glass ceramic exhibited deep-red luminescence upon the excitation of the wide wavelength range of visible light. Impressively, the Cr3+ lifetime dramatically decreased from 2.45 to 0.22 ms with the temperature increasing from 293 to 563 K, owing to the competition of radiation transitions from the thermally coupled 2E and 4T2 excited states. A two-level kinetic model was adopted to interpret this temperature-dependent luminescence of Cr3+, which gave a highest temperature sensitivity of 1.15% K(-1).