Bulletin of the American Physical Society
2017 Annual Meeting of the APS Mid-Atlantic Section
Volume 62, Number 19
Friday–Sunday, November 3–5, 2017; Newark, New Jersey
Session M4: Chemistry and Energy Science-I |
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Chair: Bruce Koel, Princeton University Room: 225, Campus Center, NJIT |
Sunday, November 5, 2017 10:00AM - 10:36AM |
M4.00001: Ambient pressure photoelectron spectroscopy studies of photoelectrocatalysts for water splitting and CO2 reduction Invited Speaker: Bruce Koel Photoelectrocatalytic water splitting for solar hydrogen production along with photoelectrocatalytic CO2 reduction are potential new technologies that could shift U.S. power consumption away from fossil fuels toward sustainable alternatives, while taking into account the nation's large-scale need for stored chemical fuels. Fundamental information on catalyst surfaces and reaction mechanisms can aid progress in developing these technologies. Ambient pressure photoelectron spectroscopy (APPES) is an excellent technique for providing information on the water/solid interface at a molecular level, with high surface and chemical sensitivity. Here we give an overview of some of our recent APPES studies of water and methanol adsorption and dissociation on GaP, which has been reported to have high faradaic efficiency for methanol generation in pyridine solutions by solar-driven CO2 reduction. We also report on our use of APPES to investigate the interactions of adsorbed water and hydroxyl species with pure and Ni-modified CoOOH catalyst surfaces, a type of oxide electrocatalyst shown previously to be active for the oxygen evolution reaction (OER), which plays an essential role in these and many other energy conversion and storage strategies. [Preview Abstract] |
Sunday, November 5, 2017 10:36AM - 10:48AM |
M4.00002: High-Selectivity, Far-Red Emitting Squaraine Sensor for Cyanide Detection Xinglei Liu, Taihong Liu, Maira A. Valencia, Binglin Sui, Yuanwei Zhang, Kevin D. Belfield Squaraine dyes are well-known fluorophores with long wavelength absorption, large molar absorptivity, high fluorescence quantum yields, and high photostability. Their unique photophysical properties make them promising candidates in a variety of scientific and technological applications such as organic electronics, optical data storage, chemosensing, nonlinear optics, photodynamic therapy of cancer, and fluorescence probes. In this study, we report the synthesis and comprehensive characterization of the linear spectroscopic and photochemical properties of a novel TEG-substituted squaraine derivative SQ1. SQ1 exhibits strong absorption and intense fluorescence emission in the far-red spectral region and high photostability. In addition, a novel fluorescent sensing strategy using SQ1 in CTAB micellar media was developed for the sensitive and selective detection of CN$^{\mathrm{-\thinspace }}$with a detection limit of 1.7 $\mu $M, corresponding nicely to limits established by the WHO and the US EPA. This work broadens the family of squaraine dyes and demonstrates SQ1 for use as a fluorescent or visual sensing probe. [Preview Abstract] |
Sunday, November 5, 2017 10:48AM - 11:00AM |
M4.00003: Nanoscopic Wetting at Solid-Liquid Interfaces John Tomko, Ashutosh Giri, Sean O'Malley, Patrick Hopkins Understanding the effects and limitations of solid-liquid interfaces on energy transport is crucial to applications ranging from micro-scale thermal energineering to batch-scale chemical synthesis. Up to now, the majority of understanding of solid-liquid interactions has been limited to macroscale observation and experiments, with development in theory and simulation of nanoscale phenomenon only recently gaining popularity, and an even further lag in experimental exploration. In this study, we expand on current nanoscale thermal measurement techniques in order to more fully understand solid-liquid interfacial energy transport. As explored in previous works, we use thermal ablation threshold measurements of thick Au films in various liquids as a metric of thermal transport at the Au/liquid interface. Further, using ultrafast pump-probe experiments, we gain insight of energy transport through picosecond ultrasonic coupling at solid-liquid interfaces. These results are compared to macroscopic observations. We find significant variation in both ablation threshold and damping of the acoustic modes within the Au films relative to the predicted transport determined from macroscopic metrics, thermal conductivity or measured contact angle. [Preview Abstract] |
Sunday, November 5, 2017 11:00AM - 11:12AM |
M4.00004: Ion-Molecule Chemistry For Detection of Atmospheric Gaseous Oxidized Mercury Matthew Cooper, John Antley, Franscico Guzman, Alexei Khalizov The poor knowledge of the chemical speciation of oxidized mercury in the atmosphere hinders the understanding of mercury pathways in the environment. To address this problem, we investigated gas-phase reactions of a model compound (mercury dichloride, HgCl2) with sulfur hexafluoride anion (SF6-) and carbonate anion (CO3-), which are promising reagent ions for the detection of oxidized mercury compounds by Chemical Ionization Mass Spectrometry. The major objectives of our study were to identify conditions under which reagent ions react with the model compound selectively, producing a narrow range of ion products (or ultimately a single ion product) at a known yield. Product yields will be reported for a range of conditions, as well as the most probable pathways for the production of said products based on quantum-chemical calculations. [Preview Abstract] |
Sunday, November 5, 2017 11:12AM - 11:24AM |
M4.00005: Biofuel cells with pressure-immobilized enzymes on carbon nanotube sheets Biao Leng, Laila Al-qarni, Zafar Iqbal Enzymatic biofuel cells (EBFCs) convert the chemical energy of biofuels into electrical energy by employing enzymes as catalysts. In contrast to hydrogen fuel cells, EBFCs have a simple membrane-free fuel cell design due to the high catalytic specificity of the enzymes, but the power densities (POD) obtained are much lower. Although initially the primary goal of research on EBFCs was to develop a sustainable power source that can be implanted in the human body to power bio-devices, other applications, such as the use of a flexible film or EBFC patch as a wearable power source, are emerging. The POD and lifetimes of early EBFCs were not promising due to the difficulty of transporting electrons from reactive sites to the electrodes and the tendency of enzymes to migrate away from the electrodes. To mitigate the issue of electron transport, direct electron transport via carbon nanotubes (CNTs) were proven to be effective. Here, CNT sheets immobilized with enzyme using pressure technique has been implemented to fabricate the electrodes. Agar gel with glucose was used as the electrolyte and a polymer enclosure was used for packaging. The POD and lifetime of these cells will be discussed. Similar or even higher POD (over 110 $\mu $W/cm$^{\mathrm{2}})$ has been obtained compared with conventional EBFCs. We will also discuss initial ex-situ Raman measurements on bioelectrodes with a gold layer for surface enhancement in advance of performing in-situ and operando Raman spectroscopy in the EBFCs. [Preview Abstract] |
Sunday, November 5, 2017 11:24AM - 12:00PM |
M4.00006: Probing and controlling carrier concentration in complex semiconductor powders for solar water splitting - optical and structural studies Invited Speaker: Peter Khalifah The (GaN)$_{\mathrm{1-x}}$(ZnO)$_{\mathrm{x}}$ system is one of the most promising semiconductor systems discovered to date for the renewable production of hydrogen fuel through solar water splitting driven by visible light. However, the maximum (GaN)$_{\mathrm{1-x}}$(ZnO)$_{\mathrm{x}}$ quantum efficiency observed for this process is still about an order of magnitude lower than expected for a fully optimized system. Optimization has been hindered by the lack of the fundamental information about this complex semiconductor system, which has almost exclusively been studied in powder form due to the severe challenges involved in preparing thin films or single crystals of (GaN)$_{\mathrm{1-x}}$(ZnO)$_{\mathrm{x}}$. Two thrusts to better understand this material will be described. First, we have developed a new general self-referenced methodology for determining the refractive index and then the absolute absorption coefficient through diffuse reflectance measurements on loose powder samples, as opposed to the crystalline materials or dense pellets required for conventional approaches. These methods suggest that despite having a direct gap optical transition, the absolute absorption coefficient of (GaN)$_{\mathrm{1-x}}$(ZnO)$_{\mathrm{x}}$ powders is about an order of magnitude lower than the best visible light absorbing systems. Second, we have attacked the challenge of controlling the semiconductor concentration in this complex semiconductor system. We demonstrate that the infrared optical response of loose powder samples can be used to very effectively monitor the carrier concentration of this semiconductor system. Using this probe, we demonstrate suitable protocols for tuning the carrier concentration and provide insights into the mechanism by the carrier concentration is changed. [Preview Abstract] |
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