[en] Carbon dots have attracted growing research interest due to its unique properties, and are expected to be used in the field of photocatalysis to solve the visible absorption loss problem of TiO₂ (P25). In this paper, red light-emitting carbon dots (RCDs) with high fluorescence quantum yield (40%) and RCDs/P25 heterojunction photocatalysts were synthesized by a simple and green hydrothermal method. Characterization results indicated that RCDs were successfully coupled with P25, and RCDs could effectively broaden the visible absorption region of bare P25 from 410 nm to 800 nm. The photocatalytic activity of the as-synthesized RCDs/P25 on the degradation of rhodamine B (RhB) under visible light irradiation was greatly improved compared with that of bare P25. The degradation rate of RhB by 2%RCDs/P25 reached 98.4% in 150 min, the degradation efficiency was 7.4 times that of bare P25. The RCDs played an important role in improving the photocatalytic activity of RCDs/P25, which not only increased visible light absorption, but also promoted efficient separation of photogenerated electron-hole pairs. Furthermore, the possible degradation mechanism of RCDs/P25 heterojunction photocatalyst was given. (paper)

[en] Rational design and fabrication of phase junction is an important way and strategy to enhance the photocatalytic performance. In this paper, rutile/anatase phase junction is obtained in rutile nanoparticles decorated anatase thin film by laser ablation. The hydrogen generation of rutile/anatase composite film is 49.6 μL, which is remarkably higher than that of both anatase thin film and rutile decorated layer. The quantity of phase junctions between rutile and anatase is considered as a key factor of photocatalytic improvement by varying the amount of rutile nanoparticles. Moreover, the excellent photocatalytic stability of rutile/anatase composite film is also exhibited.

[en] Photocatalytic water splitting with solar energy is the most promising and environmentally friendly hydrogen production method. Having an efficient and cost-effective photocatalyst is key to hydrogen production. Cu dopant has been shown to greatly enhance photocatalytic activities. In this work, Cu²⁺ ions were doped into Beta zeolite powders (Cu–Beta) by the ion exchange method. The hydrogen evolution efficiency of Cu–Beta was much higher than the raw Beta zeolites without Cu loading. After solid phase reaction, the band gap of Cu–Beta reduced from 3.48 eV to less than 2 eV, and as a result enhanced the optical absorption intensity, particularly in the visible region. The best hydrogen evolution efficiency was 102.12 μmol · g⁻¹ · h⁻¹ when the treated temperature was 900 °C (Cu–Beta–900). The temperature of the solid phase reaction had an important influence on the photocatalytic performance of Cu–Beta; a suitable reaction temperature can greatly improve its photocatalytic performance. (paper)

[en] The damage behaviors of HfO₂/SiO₂ high reflective optical thin film fabricated by electron beam evaporation (EBE) illuminated using 1064 nm laser and 532 nm laser showed some difference. It was found that the damage was usually caused by absorptive defects and absorption near the interfaces under the irradiation of 1 064 nm laser, and the damage was caused by electronic defects and absorptive ones under irradiation of 532 nm laser and the former had lower damage threshold. Therefore, the key point to enhance the laser resistance of optical thin films at 1064 nm was to prevent the presence of the absorptive defects, and to those at 532 nm was to eliminate the electronic defects. (authors)

[en] Tuning the localized surface plasmon resonance (LSPR) in doped semiconductor nanoparticles (NPs), which represents an important characteristic in LSPR sensor applications, still remains a challenge. Here, indium tin oxide/indium tin alloy (ITO/In-Sn) bilayer films were deposited by electron beam evaporation and the properties, such as the LSPR and surface morphology, were investigated by UV–VIS–NIR double beam spectrophotometer and atomic force microscopy (AFM), respectively. By simply engineering the thickness of ITO/In-Sn NPs without any microstructure fabrications, the LSPR wavelength of ITO NPs can be tuned by a large amount from 858 to 1758 nm. AFM images show that the strong LSPR of ITO NPs is closely related to the enhanced coupling between ITO and In-Sn NPs. Blue shifts of ITO LSPR from 1256 to 1104 nm are also observed in the as-annealed samples due to the higher free carrier concentration. Meanwhile, we also demonstrated that the ITO LSPR in ITO/In-Sn NPs structures has good sensitivity to the surrounding media and stability after 30 d exposure in air, enabling its application prospects in many biosensing devices. (paper)

[en] In this paper, Lu₃Al₅O₁₂:Ce³⁺ ( LuAG:Ce³⁺) transparent ceramics were obtained by solid state reaction sintering in a flowing oxygen atmosphere. Via the solid state reaction sintering in a flowing reducing atmosphere (5%H₂ + 95%N₂), the optical transmittance was increased from 54% to 65%. The SEM images showed that the ceramic phosphor samples possessed dense microstructure. In order to increase the heat dissipation capacity, a LuAG:Ce³⁺-Al ceramic metal integration (LACMI) structure was designed and fabricated. In this way, the thermal conductivity of the LACMI can be further enhanced. In addition, the LACMI structure may be beneficial to the LED packaging. In view of the excellent thermal properties of the LACMI structure, it is promising to be applied to high power LEDs. (paper)

[en] Silver thin films covered with a graphene oxide (GO) colloid layer were fabricated in this study. The coupling between GO and localized surface plasmons of the silver thin films was investigated by optical absorption and Raman scattering experiments. The absorption spectra showed that the intensity of the plasma edge peak at 320 nm decreased but the intensity of the interband transition peak at 350 nm was enhanced by an increase of the GO colloid concentration. The surface plasmon resonance attributed to the increased absorption of incident light by the GO layer caused an increase of the Raman scattering intensities. Theoretical calculations were performed for the surface plasmon resonance properties of the GO/silver thin films, and the results were in good agreement with the experiments.

[en] Up-converted blue/red dual color emitting Tm³⁺, Yb³⁺ co-activated crystalline phosphor derived from LTA zeolites have been fabricated via a facile, highly controllable, and cost-effective method, that is, the combination of ion exchange and thermal treatment in air. Under the 980 nm laser excitation, the Tm³⁺,Yb³⁺ co-activated nepheline phosphor powders showed bright blue (480 am) and red(650 nm) emission, which were attributed to the ¹G₄ → ³H₆ and ¹G₄ → ³F₄ transitions of Tm³⁺ ion, respectively. The blue/red dual color up-conversion emission from this kind of phosphor may have applications in bio-imaging and optogenetics. (paper)

[en] Highlights: • The localized surface plasmon resonance of silver thin film was generated by ITO buffer layer. • The tunability of surface plasmon resonance wavelength was realized by varying silver thin film thickness. • Raman scattering intensity varies with silver layer thickness. • FDTD calculation results of electronic field distribution are consistent with those of experiments. - Abstract: A series of silver films with various thicknesses were deposited on ITO covered silica substrates by magnetron sputtering at room temperature. The tunability of the surface plasmon resonance wavelength was realized by varying the thickness of silver thin film. By adjusting the silver layer thickness from 5 to 40 nm, the resonance wavelength shows a blueshift, which is due to a change in the electromagnetic field coupling strength from the localized surface plasmons excited between the silver thin film and ITO layer. In contrast, when the ITO layer is absent from the system, no noticeable shift in the resonance wavelength is observed upon varying the silver thin film thickness.

[en] Highlights: • Al-Cu bimetallic nanoparticles (NPs) thin films were fabricated by Nd:YAG fiber-pulsed laser irradiation. • The tunability of both localized surface plasmon resonance (LSPR) wavelength and intensity were realized. • SERS performance and FDTD simulation were applied to demonstration the potential application of tunable LSPR properties. Al-Cu bimetallic nanoparticles (NPs) thin film was fabricated by Nd:YAG fiber pulsed-laser irradiation of Al/Cu bilayers at ambient conditions. The effects of laser irradiation on the morphology, structure, composition and optical properties of the samples were investigated. The tunability of both localized surface plasmon resonance (LSPR) wavelength and intensity were realized by varying the pulse shot or relative thickness of Al/Cu bilayers. The SEM analysis with EDS results further revealed that the obtained particles consisted of a mean diameter of 36–80 nm bimetallic NPs system, being dependent on the Cu proportion. In addition, Surface-enhanced Raman spectroscopy (SERS) measurement and corresponding finite-difference time-domain (FDTD) simulation of before and after laser irradiation samples were discussed to verify the LSPR properties.