[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] So far, the self-assembly buckling patterns of thin films on flexible substrates have been subjected to extensive studies. In most of previous studies, self-assembly wrinkles were fabricated on planar substrates, and less attention were put on the curved substrates. Here, we proposed a technique to obtain self-assembly ring wrinkles on the cylindrical surface of polydimethylsiloxane cylinders. Ultraviolet Ozone exposure was performed on pre-stretched PDMS cylinders that were kept rotating, resulting in ring wrinkles upon release. We researched the effect of pre-stretch and exposure time on the period and amplitude of the wrinkles through simulations and experiments. The experimental result is consistent with the simulated results by the model of plane wrinkling. Our results can lead to use in applications such as pressure sensors and human motion detection. (paper)

[en] Graphical abstract: - Highlights: • A facile and rapid one-pot synthesis method is presented. • The effects of various Ga contents are investigated. • Single phase chalcopyrite CuIn_1−xGa_xSe₂ nanoparticles can be easily synthesized. • The phase formation sequence is from CuSe to CuGaSe₂, then to CuIn_1−xGa_xSe₂. • The possible reaction mechanism of CuIn_1−xGa_xSe₂ nanoparticles is proposed. - Abstract: Single phase chalcopyrite and near stoichiometric CuIn_1−xGa_xSe₂ (0 ≤ x ≤ 1) nanoparticles were successfully synthesized by using a facile and rapid one-pot method. The effects of various Ga contents on crystal phase, morphology, element composition and absorption spectrum of the as-synthesized CuIn_1−xGa_xSe₂ nanoparticles were investigated in detail. The XRD and Raman patterns indicated that the as-synthesized nanoparticles had a single phase chalcopyrite structure, and the diffraction peaks shifted toward larger diffraction angles or higher frequencies with increasing Ga content. The FE-SEM images showed that the as-synthesized nanoparticles were polydispersed in both size and shape, and the nanoparticles with higher Ga content were more prone to aggregate. The Vis–IR absorption spectra showed strong absorption in the entire visible light region. The estimated band gap increased from 1.00 eV to 1.68 eV as Ga content increasing

[en] Highlights: • High precision neutral density filters by ultra-precisely controlling the thickness. • Atomic-layer etching is achieved by bombarding films with low energy ion beams. • Showed the different etching condition of Hall and Kauffman ion source. Ni80Cr20 alloy film shows a good neutral transmission in visible light. A large area and high precision neutral density filter with multiple steps made of Ni80Cr20 is presented in this work, which proposes one manufacturing method for controlling film thickness. The quartz crystal sensor in the coating machine has a thickness uncertainty larger than 5%, which leads to the low accuracy of optical density value of the filter. To solve this problem, we bombarded the membrane surface with low energy ion beams when the optical density of the filter was slightly larger than we wanted. The absolute error of optical density could then be controlled within 0.01, and the relative error is ±2%, a result which is much better than those that accompany existing commercial neutral density filters. Finally, a neutral density filters with 18 steps is manufactured, which can used as a component of a spectral sensitivity spectrometer.