Selective Oxofunctionalization of Cyclohexene over Titanium Dioxide-Based and Bismuth Oxyhalide Photocatalysts by Visible Light Irradiation

Photocatalysis driven under visible light allows us to carry out hydrocarbon oxofunctionalization under ambient conditions, using molecular oxygen as a sacrificial reagent, with the absence of hazardous subproducts and the potential use of the Sun as a clean and low-cost source of light. In this work, eight materials—five based on titanium dioxide and three based on bismuth oxyhalides—were used as photocatalysts in the selective oxofunctionalization of cyclohexene. The cyclohexane oxofunctionalization reactions were performed inside of a homemade photoreactor equipped with a 400 W metal halide lamp and injected air as a source of molecular oxygen. In all assayed systems, the main oxygenated products, identified by mass spectrometry, were 1,2-epoxycyclohexane, 2-cyclohexen-1-ol, and 2-cyclohexen-1-one. Titanium dioxide-based materials exhibited higher selectivities for 1,2-epoxycyclohexane than bismuth oxyhalide-based materials. In addition to this, titanium dioxide doped with iron exhibited the best selectivity for 1,2-epoxycyclohexane, demonstrating that iron plays a relevant role in the cyclohexene epoxidation process.

Low-Glare Freeform-Surfaced Street Light Luminaire Optimization to Meet Enhanced Road Lighting Standards

To enhance driving safety at night, a new freeform-surface street light luminaire was proposed and evaluated in this study that meets the requirements of the International Commission on Illumination (CIE) M3 class standard for road lighting. The luminaire was designed using simulations to optimize the location of the bulb according to the requirements of the standard. The light source IES file was experimentally obtained for the optimized luminaire prototype with a 150 W ceramic metal halide lamp using an imaging goniophotometer. The trial road lighting simulation results computed by the lighting software DIALux indicated that the proposed luminaire provided an average road surface brightness of 1.1 cd/m2 (compared to a minimum requirement of 1.0 cd/m2), a brightness uniformity of 0.41 (compared to a minimum requirement of 0.4), a longitudinal brightness uniformity of 0.64 (compared to a minimum requirement of 0.6), and a glare factor of 7.6% (compared to a maximum limit of 15%). The findings of the image goniophotometer tests were then confirmed by the results of a certified mirror goniophotometer test conducted by the Taiwan Accreditation Foundation (TAF). The results of this study can be used to provide improved street lighting designs to meet enhanced international standards.

Preparation and Photocatalytic Property of Ag Modified Titanium Dioxide Exposed High Energy Crystal Plane (001)

TiO2 exposed high energy crystal plane (001) was prepared by the sol-gel process using butyl titanate as the titanium source and hydrofluoric acid as the surface control agent. Ag-TiO2 was prepared by depositing Ag on the crystal plane of TiO2 (101) with a metal halide lamp. The surface morphology, interplanar spacing, crystal phase composition, ultraviolet absorption band, element composition, and valence state of the samples were characterized by using field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD), ultraviolet-visible absorption spectrum (UV-Vis-Abs), and X-ray photoelectron spectroscopy (XPS), respectively. The formation mechanism of high energy crystal plane (001) was discussed, and the photocatalytic activities were evaluated by following degradation of methyl orange. The results show that TiO2 exposed the (001) crystal plane with a ratio of 41.8%, and Ag can be uniformly deposited on the crystal plane of TiO2 (101) by means of metal halide lamp deposition. Under the same conditions, the degradation rate of methyl orange by deposited Ag-TiO2 reaches as much as 93.63% after 60 min using the metal halide lamp (300 W) as an illuminant, 81.89% by non-deposited samples and 75.20% by nano-TiO2, causing a certain blue shift in the light absorption band edge of TiO2. Ag-TiO2 has the best photocatalytic performance at a pH value of 2.