MULTI-NEEDLE FIBEROPTIC RAMAN SPECTROSCOPY TECHNIQUE FOR SIMULTANEOUS MULTI-SITE DEEP TISSUE RAMAN MEASUREMENTS

Master'sMASTER OF ENGINEERING (CDE

Mesoporous TiO₂ Nanocrystals Grown in Situ on Graphene Aerogels for High Photocatalysis and Lithium-Ion Batteries

TiO₂/graphene composites have been well studied as a solar light photocatalysts and electrode materials for lithium-ion batteries (LIBs). Recent reports have shown that ultralight 3D-graphene aerogels (GAs) can better adsorb organic pollutants and can provide multidimensional electron transport pathways, implying a significant potential application for photocatalysis and LIBs. Here, we report a simple one-step hydrothermal method toward in situ growth of ultradispersed mesoporous TiO₂ nanocrystals with (001) facets on GAs. This method uses glucose as the dispersant and linker owing to its hierarchically porous structure and a high surface area. The TiO₂/GAs reported here exhibit a highly recyclable photocatalytic activity for methyl orange pollutant and a high specific capacity in LIBs. The strong interaction between TiO₂ and GAs, the facet characteristics, the high electrical conductivity, and the three-dimensional hierarchically porous structure of these composites results in highly active photocatalysis, a high rate capability, and stable cycling

Artificial photosynthesis bringing new vigor into plastic wastes

Abstract The accumulation of plastic wastes in landfills and the environment threatens our environment and public health, while leading to the loss of potential carbon resources. The urgent necessary lies in developing an energy‐saving and environmentally benign approach to upgrade plastic into value‐added chemicals. Artificial photosynthesis holds the ability to realize plastic upcycling by using endless solar energy under mild conditions, but remains in the initial stage for plastic upgrading. In this review, we aim to look critically at the photocatalytic conversion of plastic wastes from the perspective of resource reutilization. To begin with, we present the emerging conversion routes for plastic wastes and highlight the advantages of artificial photosynthesis for processing plastic wastes. By parsing photocatalytic plastic conversion process, we demonstrate the currently available routes for processing plastic, including plastic photodegradation, tandem decomposition of plastic and CO2 reduction, selective plastic oxidation, as well as photoreforming of plastic. This review concludes with a personal perspective for potential advances and emerging challenges in photocatalytic plastic conversion

Visible-Light-Driven Semiconductor–Metal Transition in Electron Gas at the (100) Surface of KTaO₃

Two-dimensional electron gas (2DEG) at the (100) KTaO3(KTO) surface and interfaces has attracted extensive interest because of its abundant physical properties. Here, light illumination-induced semiconductor–metal transition in the 2DEG at the KTO surface was investigated. 2DEG was formed at the surface of KTO by argon ion bombardment. The 2DEG prepared with a shorter bombardment time (300 s) exhibits semiconducting behavior in the range of 20~300 K in the dark. However, it shows a different resistance behavior, namely, a metallic state above ~55 K and a semiconducting state below ~55 K when exposed to visible light (405 nm) with a giant conductivity increase of about eight orders of magnitude at 20 K. The suppression of the semiconducting behavior is found to be more pronounced with increasing light power. After removing the illumination, the resistance cannot recover quickly, exhibiting persistent photoconductivity. More interestingly, the photoresponse of the 2DEG below 50 K was almost independent of the laser wavelength, although the photon energy is lower than the band gap of KTO. The present results provide experimental support for tuning oxide 2DEG by photoexcitation, suggesting promising applications of KTO-based 2DEG in future electronic and optoelectronic devices

Rational Design of a Unique Ternary Structure for Highly Photocatalytic Nitrobenzene Reduction

The rational design and controllable synthesis of TiO₂ and noble metal composite photocatalysts represent an unprecedented challenge for developing the solar-driven reduction of nitrobenzene (NB) to aminobenzene (AB), owing to the recombination over the interface between the noble metals and TiO₂, which is harmful to the conversion efficiency of NB to AB. Here, we design a unique ternary structure (the high separation of TiO₂ and Pt nanoparticles on the surface of reduced graphene oxide (RGO)) through the sol–gel and microwave-assisted strategies. The substrate of RGO can be used as an “electric wire” to effectively transfer the photogenerated electrons from the isolated TiO₂ nanocrystals to the isolated Pt nanoparticles, which greatly decreases the interface recombination between TiO₂ and Pt and further improves the conversion efficiency of NB to AB under the solar light irradiation. We anticipate our research provides a new way to overcome the interface recombination on the binary photocatalysts in the photocatalytic reaction