Shuit-Tong Lee

Bio: Shuit-Tong Lee is an academic researcher from Soochow University (Suzhou). The author has contributed to research in topics: Silicon & Nanowire. The author has an hindex of 138, co-authored 1121 publications receiving 77112 citations. Previous affiliations of Shuit-Tong Lee include University of British Columbia & Hong Kong University of Science and Technology.

Chemical synthesis and structural studies of thiol-capped gold nanoparticles

Abstract: We report the chemical synthesis and structural studies of thiol-capped Au nanoparticles (NPs) using extended X-ray absorption fine structures (EXAFS) and high-resolution transmission electron micr...

Fluorination induced etching selectivity of boron nitride phases

Abstract: Selective etching by hydrogen for different carbon phases is pivotal in enabling the synthesis of diamond using low-pressure chemical vapor deposition (CVD) However, this is not the case in the CVD synthesis of cubic boron nitride (c-BN) Here, by carrying out a systematic atomic-level study using the frontier orbital theory based on ab initio calculations, we show that, upon fluorination at the boron site, the etching selectivity of both hydrogen and fluorine for different boron nitride phases is significantly enhanced By examining the electronic structural change, we found that the etching selectivity enhancement relates to the boundary saturation improvement upon fluorination Moreover, fluorination also enhances the structural stability, particularly at the surface layers, providing a suitable environment for maintaining a proper charge transfer between boron and nitrogen atoms, which is the key factor for determining reactivity and stability The enhanced etching selectivity would facilitate the CV

Inhibition of biochemical reactions by silicon nanowires through modulating enzyme activities.

Abstract: Nanotechnology has infiltrated the field of biology in the form of quantum dots, carbon nanotubes and silicon nanowires (SiNWs), with applications in biosensors, in vivo and in vitro imaging, tissue engineering and biomedical devices. With the envisaged broad application of nanomaterials, the potential effects of nanomaterials in both biological systems and the environment should be thoroughly evaluated before full advantage of nanotechnology can be taken. Efforts have been made to investigate in vivo and in vitro toxicity of carbon nanotubes, quantum dots and metal nanoparticles. Oxidative stress induced by nanomaterials that interact with biological systems might cause the ACHTUNGTRENNUNGrelease of inflammatory cytokines and cytotoxic cellular response. There is also evidence to indicate that aggregates of nanomaterials or the release of toxic chemicals under ultraviolet (UV) radiation can induce in vivo and in vitro toxicity. The main characteristics of nanomaterials, such as small size and large surface area, might be responsible for the material interactions that could result in toxicological effects. Nevertheless, little work has been done to study the potential effect of SiNWs on biological systems and the environment. Here, we investigate the potential effects of “as-grown” unmodified silicon nanowires (SiNW-SiO2) and SiNWs functionalized with carboxylic groups (SiNW-COOH) on prototypical ACHTUNGTRENNUNGenzymes in biology, namely, restriction endonucleases and Taq DNA polymerase. It is important for any living organism to ensure the duplication of its genetic material. The central enzyme that performs this complicated task is DNA polymerase. Restriction endonucleases can recognize short DNA sequences and cause cleavage in either one or both strands. These enzymes are important tools for studying primary DNA structure, in recombinant DNA technology and other fields of molecular genetics and biology. The SiNWs used in this study were prepared by oxide-assisted growth by using simple thermal evaporation of silicon monoxide powder as the single source. The “as-grown” SiNWs had a crystalline silicon core of 15–20 nm in diameter and a silicon oxide sheath of 3–5 nm in thickness (Figure 1A). Thus, the surface of the SiNWs was hydrophobic and neutral. The oxide sheath was removed by immersing the SiNWs in aqueous HF

Interfacial electronic structure of copper hexadecafluorophthalocyanine and phthalocyanatotin (IV) dichloride studied by photoemission spectroscopy

Abstract: We investigated the interfacial electronic structure of the n-n isotype organic heterojunction formed between copper hexadecafluorophthalocyanine (F16CuPc) and phthalocyanatotin (IV) dichloride (SnCl2Pc) using ultraviolet and x-ray photoemission spectroscopies. Energy level bending was observed at the heterojunction interface due to the formation of an electron accumulation region in the F16CuPc layer and an electron depletion region in the SnCl2Pc layer. The formation of organic heterojunction was explained by charge exchange at the interface due to their different work functions.

A roadmap for graphene

Abstract: Recent years have witnessed many breakthroughs in research on graphene (the first two-dimensional atomic crystal) as well as a significant advance in the mass production of this material. This one-atom-thick fabric of carbon uniquely combines extreme mechanical strength, exceptionally high electronic and thermal conductivities, impermeability to gases, as well as many other supreme properties, all of which make it highly attractive for numerous applications. Here we review recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.

High-performance lithium battery anodes using silicon nanowires

Abstract: There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.

Nanobelts of Semiconducting Oxides

Abstract: Ultralong beltlike (or ribbonlike) nanostructures (so-called nanobelts) were successfully synthesized for semiconducting oxides of zinc, tin, indium, cadmium, and gallium by simply evaporating the desired commercial metal oxide powders at high temperatures. The as-synthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are free from defects and dislocations. They have a rectanglelike cross section with typical widths of 30 to 300 nanometers, width-to-thickness ratios of 5 to 10, and lengths of up to a few millimeters. The beltlike morphology appears to be a distinctive and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures. The nanobelts could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides and building functional devices along individual nanobelts.

Raman spectroscopy as a versatile tool for studying the properties of graphene

Abstract: Raman spectroscopy is an integral part of graphene research. It is used to determine the number and orientation of layers, the quality and types of edge, and the effects of perturbations, such as electric and magnetic fields, strain, doping, disorder and functional groups. This, in turn, provides insight into all sp(2)-bonded carbon allotropes, because graphene is their fundamental building block. Here we review the state of the art, future directions and open questions in Raman spectroscopy of graphene. We describe essential physical processes whose importance has only recently been recognized, such as the various types of resonance at play, and the role of quantum interference. We update all basic concepts and notations, and propose a terminology that is able to describe any result in literature. We finally highlight the potential of Raman spectroscopy for layered materials other than graphene.

Aggregation-Induced Emission: Together We Shine, United We Soar!

Abstract: Ju Mei,†,‡,∥ Nelson L. C. Leung,†,‡,∥ Ryan T. K. Kwok,†,‡ Jacky W. Y. Lam,†,‡ and Ben Zhong Tang*,†,‡,§ †HKUST-Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China ‡Department of Chemistry, HKUST Jockey Club Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, State Key Laboratory of Molecular Neuroscience, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China