Engineering Commons^™

Sonochemical Synthesis Of Zinc Oxide Nanostructures For Sensing And Energy Harvesting, Phani Kiran Vabbina

FIU Electronic Theses and Dissertations

Semiconductor nanostructures have attracted considerable research interest due to their unique physical and chemical properties at nanoscale which open new frontiers for applications in electronics and sensing. Zinc oxide nanostructures with a wide range of applications, especially in optoelectronic devices and bio sensing, have been the focus of research over the past few decades. However ZnO nanostructures have failed to penetrate the market as they were expected to, a few years ago. The two main reasons widely recognized as bottleneck for ZnO nanostructures are (1) Synthesis technique which is fast, economical, and environmentally benign which would allow the growth on …

Microstructure And Mechanical Properties Of Nanofiller Reinforced Tantalum-Niobium Carbide Formed By Spark Plasma Sintering, Christopher Charles Rudolf

FIU Electronic Theses and Dissertations

Ultra high temperature ceramics (UHTC) are candidate materials for high temperature applications such as leading edges for hypersonic flight vehicles, thermal protection systems for spacecraft, and rocket nozzle throat inserts due to their extremely high melting points. Tantalum and Niobium Carbide (TaC and NbC), with melting points of 3950°C and 3600°C, respectively, have high resistivity to chemical attack, making them ideal candidates for the harsh environments UHTCs are to be used in. The major setbacks to the implementation of UHTC materials for these applications are the difficulty in consolidating to full density as well as their low fracture toughness. In …

Visible-Light-Responsible Co-Catalysts Enhanced By Graphene For Solar Energy Harvesting, Chen Ying

Masters Theses & Specialist Projects

This study focuses on the visible light response of hetero-structures of TiO2-graphene- MoS2 for solar energy harvestings. The commercial P25 TiO2 nano-particles, and selfprepared layered reduced graphene oxides (RG) and MoS2 were assembled for the targeted hetero-structure materials as visible-light responsible solar harvesting cocatalysts. The hydrothermal method was applied for nano-material synthesis, the reduction of graphene oxides, and bonding formation. Multiple characterization methods (SEM-TEM, XRD, XPS, UV-VIS, PL, FT-IR, TGA) have been applied to understand the electron-hole pair separation and recombination, and performance tuning in their visible-light photo-catalysis rhodamine B (Rh.B) degradations process

Compared to TiO2, an obvious red shift …

An Equivalent Circuit Model For Graphene-Based Terahertz Antenna Using The Peec Method, Ying S. Cao, Li (Lijun) Jun Jiang, Albert E. Ruehli

Electrical and Computer Engineering Faculty Research & Creative Works

The electromagnetic (EM) characterization of graphene under general EM environments is becoming of interest in the engineering and scientific research fields. However, its numerical modeling process is extremely cost prohibitive due to the huge contrast between its thickness and other dimensions. In this work, for the first time, the EM features of graphene are characterized by a circuit model through the partial element equivalent circuit (PEEC) method. The atomically thick graphene is equivalently replaced by an impedance boundary condition. After incorporating the PEEC method, a novel surface conductivity circuit model is derived for graphene. A physical resistor and inductor are …

Advanced Graphene Microelectronic Devices, Chowdhury G. Al-Amin

FIU Electronic Theses and Dissertations

The outstanding electrical and material properties of Graphene have made it a promising material for several fields of analog applications, though its zero bandgap precludes its application in digital and logic devices. With its remarkably high electron mobility at room temperature, Graphene also has strong potential for terahertz (THz) plasmonic devices. However there still are challenges to be solved to realize Graphene’s full potential for practical applications.

In this dissertation, we investigate solutions for some of these challenges. First, to reduce the access resistances which significantly reduces the radio frequency (RF) performance of Graphene field effect transistors (GFETs), a novel …

Large-Area Graphene-Based Nanofiltration Membranes By Shear Alignment Of Discotic Nematic Liquid Crystals Of Graphene Oxide, Abozar Akbari, Phillip Sheath, Samuel T. Martin, Dhanraj B. Shinde, Mahdokht Shaibani, Parama Chakraborty Banerjee, Rachel Tkacz, Dibakar Bhattacharyya, Mainak Majumder

Chemical and Materials Engineering Faculty Publications

Graphene-based membranes demonstrating ultrafast water transport, precise molecular sieving of gas and solvated molecules shows great promise as novel separation platforms; however, scale-up of these membranes to large-areas remains an unresolved problem. Here we demonstrate that the discotic nematic phase of graphene oxide (GO) can be shear aligned to form highly ordered, continuous, thin films of multi-layered GO on a support membrane by an industrially adaptable method to produce large-area membranes (13 × 14 cm²) in < 5 s. Pressure driven transport data demonstrate high retention (> 90%) for charged and uncharged organic probe molecules with a hydrated radius above 5 Å as well as modest (30–40%) retention of …

Silk-Derived Graphene-Like Carbon With High Electrocatalytic Activity For Oxygen Reduction Reaction, Qingfa Wang, Ruoping Yanzhang, Yaqing Wu, Han Zhu, Junfeng Zhang, Mingliang Du, Ming Zhang, Li Wang, Xiangwen Zhang, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

A facile method to prepare the nanoporous and graphene-like carbon material from a natural silk fiber was developed by a potassium intercalation and carbonization procedure. The as-synthesized graphene-like fiber was employed for oxygen reduction reaction and exhibited impressive electrocatalytic activity.

Characterisation Of Graphene Fibres And Graphene Coated Fibres Using Capacitively Coupled Contactless Conductivity Detector, Joan M. Cabot, Emer Duffy, Sinead Currivan, Andres Ruland Palaia, Rouhollah Jalili, Attila J. Mozer, Peter C. Innis, Gordon G. Wallace, Michael C. Breadmore, Brett Paull

Australian Institute for Innovative Materials - Papers

The use of capacitively coupled contactless conductivity detection (C 4 D) for the characterisation of thin conductive graphene fi bres, graphene composite fi bres, and graphene coated fi brous materials is demon- strated for the fi rst time. Within a few seconds, the non-destructive C 4 D detector provides a pro fi le of the longetudinal physical homogeneity of the fi bre, as well as extra information regarding fi bre mophology and composition. In addition to the theoretical considerations related to the factors a ff ect the output signal, this work evaluates the properties of graphene fi bres using scanning …

Nitrogen-Doped Graphene Ribbon Assembled Core-Sheath Mno@Graphene Scrolls As Hierarchically Ordered 3d Porous Electrodes For Fast And Durable Lithium Storage, Yun Zhang, Penghui Chen, Xu Gao, Bo Wang, Heng Liu, Haobin Wu, Hua-Kun Liu, Shi Xue Dou

Australian Institute for Innovative Materials - Papers

Graphene scroll is an emerging 1D tubular form of graphitic carbon that has potential applications in electrochemical energy storage. However, it still remains a challenge to composite graphene scrolls with other nanomaterials for building advanced electrode configuration with fast and durable lithium storage properties. Here, a transition-metal-oxide-based hierarchically ordered 3D porous electrode is designed based on assembling 1D core-sheath MnO@N-doped graphene scrolls with 2D N-doped graphene ribbons. In the resulting architecture, porous MnO nanowires confined in tubular graphene scrolls are mechanically isolated but electronically wellconnected, while the interwoven graphene ribbons offer continuous conductive paths for electron transfer in all directions. …

Oxygen-Free Layer-By-Layer Assembly Of Lithiated Composites On Graphene For Advanced Hydrogen Storage, Guanglin Xia, Yingbin Tan, Xiaowei Chen, Fang Fang, Dalin Sun, Xingguo Li, Zaiping Guo, Xuebin Yu

Australian Institute for Innovative Materials - Papers

A facile hydrogenation-induced self-assembly strategy to synthesize lithium hydride (LiH) nanosheets with a thickness of 2 nm that are uniformly distributed on graphene is reported and designed. Taking advantage of LiH nanosheets with high reactivity and a homogeneous distribution on graphene support as a nanoreactor, the confined chemical synthesis of oxygen-free lithiated composites is effectively and efficiently realized.

Nonlocal Transistor Based On Pure Crossed Andreev Reflection In A Euo-Graphene/Superconductor Hybrid Structure, Yee Sin Ang, Lawrence Ang, C Zhang, Zhongshui Ma

Faculty of Engineering and Information Sciences - Papers: Part A

We study the interband transport in a superconducting device composed of graphene with EuO-induced exchange interaction. We show that pure crossed Andreev reflection can be generated exclusively without the parasitic local Andreev reflection and elastic cotunnelling over a wide range of bias and Fermi levels in an EuO-graphene/superconductor/EuO-graphene device. The pure nonlocal conductance exhibits rapid on-off switching and oscillatory behavior when the Fermi levels in the normal and the superconducting leads are varied. The oscillation reflects the quasiparticle propagation in the superconducting lead and can be used as a tool to probe the subgap quasiparticle mode in superconducting graphene, which …

Confined Sno2 Quantum-Dot Clusters In Graphene Sheets As High-Performance Anodes For Lithium-Ion Batteries, Chengling Zhu, Shenmin Zhu, Kai Zhang, Zeyu Hui, Hui Pan, Zhixin Chen, Yao Li, Di Zhang, Dawei Wang

Faculty of Engineering and Information Sciences - Papers: Part A

Construction of metal oxide nanoparticles as anodes is of special interest for next-generation lithium-ion batteries. The main challenge lies in their rapid capacity fading caused by the structural degradation and instability of solid-electrolyte interphase (SEI) layer during charge/discharge process. Herein, we address these problems by constructing a novel-structured SnO₂-based anode. The novel structure consists of mesoporous clusters of SnO₂ quantum dots (SnO₂ QDs), which are wrapped with reduced graphene oxide (RGO) sheets. The mesopores inside the clusters provide enough room for the expansion and contraction of SnO₂ QDs during charge/discharge process while the integral structure …

Encapsulation Of Fe3o4 Nanoparticles Into N, S Co-Doped Graphene Sheets With Greatly Enhanced Electrochemical Performance, Zunxian Yang, Kun Qian, Jun Lv, Wenhuan Yan, Jiahui Liu, Jingwei Ai, Yuxiang Zhang, Tailiang Guo, Xiongtu Zhou, Sheng Xu, Zaiping Guo

Faculty of Engineering and Information Sciences - Papers: Part A

Particular N, S co-doped graphene/Fe₃O₄ hybrids have been successfully synthesized by the combination of a simple hydrothermal process and a subsequent carbonization heat treatment. The nanostructures exhibit a unique composite architecture, with uniformly dispersed Fe₃O₄ nanoparticles and N, S co-doped graphene encapsulant. The particular porous characteristics with many meso/micro holes/pores, the highly conductive N, S co-doped graphene, as well as the encapsulating N, S co-doped graphene with the high-level nitrogen and sulfur doping, lead to excellent electrochemical performance of the electrode. The N-S-G/Fe₃O₄ composite electrode exhibits a high initial reversible capacity …

Graphene/Pvdf Flat-Sheet Membrane For The Treatment Of Ro Brine From Coal Seam Gas Produced Water By Air Gap Membrane Distillation, Yun Chul Woo, Youngjin Kim, Wang-Geun Shim, Leonard D. Tijing, Minwei Yao, Long D. Nghiem, June-Seok Choi, Seung-Hyun Kim, Ho Kyong Shon

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.

Graphene-Wrapped Reversible Reaction For Advanced Hydrogen Storage, Guanglin Xia, Yingbin Tan, Feilong Wu, Fang Fang, Dalin Sun, Zaiping Guo, Zhenguo Huang, Xuebin Yu

Australian Institute for Innovative Materials - Papers

Here, we report the fabrication of a graphene-wrapped nanostructured reactive hydride composite, i.e., 2LiBH4-MgH2, made by adopting graphene-supported MgH2 nanoparticles (NPs) as the nanoreactor and heterogeneous nucleation sites. The porous structure, uniform distribution of MgH2 NPs, and the steric confinement by flexible graphene induced a homogeneous distribution of 2LiBH4-MgH2 nanocomposite on graphene with extremely high loading capacity (80 wt%) and energy density. The well-defined structural features, including even distribution, uniform particle size, excellent thermal stability, and robust architecture endow this composite with significant improvements in its hydrogen storage performance. For instance, at a temperature as low as 350 °C, a …