The Electrochemistry of Two-Dimensional Materials and Their Heterostructures for Energy Applications

Meeting the growing energy demands of the 21st century is one of the greatest problems facing humanity, which has led to intense research into improving energy generation, storage, and transportation. To meet this challenge, many researchers have focused on nanomaterials, which offer unique opportunities for property modulation, attractive kinetics, and increased surface area. Two-dimensional (2D) materials are a class of nanomaterial consisting of atomically thin sheets with a wide range of attractive properties and the weak interlayer van der Waals interactions in these compounds can be exploited to stack layers of different materials with an atomically smooth interface to form a hybrid material called a heterostructure. Despite recent advances in identifying promising 2D materials and heterostructures for potential applications for energy technology, there is a significant need for the development of mechanistic understandings of these materials. In this dissertation, 2D materials are integrated into a nanodevice architecture to systematically probe the mechanisms of 2D electrochemical energy materials. We investigate the synthesis of high-quality monolayer crystals of MoS2, and highlight the role of elevated sulfur concentration in suppressing the formation of unwanted suboxide and oxysulfide intermediate products during the stepwise sulfurization of MoO3 to MoS2. Using these high-quality crystals of MoS2, we investigate the electrocatalytic production of hydrogen with MoS2/WTe2 heterostructures, and demonstrate that enhanced charge injection through the heterointerface optimizes the catalytic performance of MoS2. Our investigation of the electrochemical intercalation of lithium into heterostructures of hexagonal boron nitride, graphene, and MoS2 demonstrates the key role that heterointerfaces play in controlling both the kinetics and thermodynamics of the lithium-induced structural phase transition in MoS2. We further probe the staging of intercalated lithium within graphene, and the effect of mechanical strain on this ordering. Finally, we investigate the influence of the thickness of MoS2 flakes on the kinetics of its lithium-induced structural phase transition. The nanodevice approach in this dissertation seeks to systematically probe the factors that can affect the electrochemistry of 2D energy materials. We demonstrate the importance of charge injection upon the performance of 2D electrocatalysts and how heterointerfaces, support substrates, and mechanical strain can modify the phase stability and intercalation dynamics of 2D materials. These findings have implications for the production of renewable fuels, nanostructuring metal-ion battery and supercapacitor electrodes, and for many other device applications utilizing 2D nanomaterials. Our aim is to inform future materials engineering and energy device architecture for the next generation of nanostructured energy technology

The Determination of the Aqueous Oxidation Potentials of Aniline and Sixteen of its Derivatives via Ultrafast Cyclic Voltammetry to Model the Photocatalyzed Degradation of Organic Pollutants in Natural Bodies of Water

Redox reactions of organic pollutants are important processes to consider when studying the effect of pollutants on the environment. Having accurate aqueous formal oxidation potentials (E0’) for pollutants is essential to understanding their redox chemistry and how they might react with photoactivated dissolved organic matter in natural bodies of water. Aniline and sixteen of its derivatives were studied with cyclic voltammetry and ultrafast cyclic voltammetry in order to determine their aqueous oxidation potentials. Due to the rapid polymerization of aniline upon oxidation, cyclic voltammetry at macroelectrodes is unable to detect reduction, and thus measures an irreversible process. Using a 3.00 mm glassy-carbon macroelectrode and scan rates on the order of 1 Vs-1 the irreversible oxidation of the anilines was observed, and the reversible E0’ was approximated by the inflection points of their oxidation peaks. This data was further analyzed based on the resonance and electron donating / withdrawing effects of the various aniline substituents. In order to study the reversible process, ultrafast cyclic voltammetry was used in an attempt to reduce aniline radical cations before they are consumed by the polymerization reaction. An 11 μm carbon fiber, a 10 μm gold, and a 10 μm platinum microelectrode were employed at scan rates between 200 Vs-1 and 1,000 Vs-1. This technique was successful at measuring a reversible redox couple for some of the anilines; however, further experimentation is required to collect accurate data for all anilines

The development of 2D materials for electrochemical energy applications: A mechanistic approach

Energy production and storage is one of the foremost challenges of the 21st century. Rising energy demands coupled with increasing materials scarcity have motivated the search for new materials for energy technology development. Nanomaterials are an excellent class of materials to drive this innovation due to their emergent properties at the nanoscale. In recent years, two dimensional (2D) layered materials have shown promise in a variety of energy related applications due to van der Waals interlayer bonding, large surface area, and the ability to engineer material properties through heterostructure formation. Despite notable results, their development has largely followed a guess and check approach. To realize the full potential of 2D materials, more efforts must be made towards achieving a mechanistic understanding of the processes that make these 2D systems promising. In this perspective, we bring attention to a series of techniques used to probe fundamental energy related processes in 2D materials, focusing on electrochemical catalysis and energy storage. We highlight studies that have advanced development due to mechanistic insights they uncovered. In doing so, we hope to provide a pathway for advancing our mechanistic understanding of 2D energy materials for further research

Fundamentally Human: Contemporary Art and Neuroscience

Fundamentally Human: Contemporary Art and Neuroscience exhibition brings the work of seven contemporary artists to the fore, whose work addresses aspects of the neurological sciences. Curated by BFA Fine Arts Department Chair of the School of Visual Arts in New York Suzanne Anker, the exhibition includes works by the artists Suzanne Anker (USA), Andrew Carnie (UK), Rona Pondick (USA), Michael Joaquin Grey (USA), Michael Rees (USA), Frank Gillette (USA) and Leonel Moura (Portugal).Each interdisciplinary artist essentially employs new technologies ranging from robotics, 3-D scanning, Photoshop, rapid prototyping, microscopy and computational video. All are concerned with the mysteries and unity of nature and its processes, the transmission of knowledge and beliefs, and the reveries of human metaphors of being in time.As the artists incorporate such metaphors invoked by matter, perception and memory, their discrete personifications are framed within a symbolic narrative.This exhibition which combines science and art; invites us to view art through a scientific perspective and help us understand and question the strong connection between contemporary art and neuroscience

'Alienated From His Own Being': Nietzsche, Bayreuth and the Problem of Identity

The abstract is included in the text

Additional file 12: Table S11. of Long noncoding RNAs expressed in human hepatic stellate cells form networks with extracellular matrix proteins

Expression levels of lncRNAs and their divergent paired coding genes in HSC myofibroblasts. (XLS 310 kb