Chemistry - Journal Articles

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    Water-soluble binders that improve electrochemical sodium-ion storage properties in a NaTi2(PO4)3 anode
    (IOP Publishing, 2023-05-22) Zhang, Yan; Grant, Alex; Carroll, Aoife; Gulzar, Umair; Ferguson, Matthew; Roy, Ahin; Nicolosi, Valeria; O'Dwyer, Colm; Horizon 2020; Irish Research Council; Science Foundation Ireland
    Water-soluble binders are demonstrated to provide significantly better capacity, cycle life stability and rate response for NASICON-type NaTi2(PO4)3 Na-ion battery anodes during reversible sodiation compared to electrodes made using polyvinylidene difluoride-containing slurries. The role of carboxymethyl cellulose (CMC) binders on the physical structure and chemical interfacial reactions with sodium-poor NaTi2(PO4)3 are uncovered using electron microscopy and spectroscopy data and we show that a more stable NASICON NaTi2(PO4)3 structure is found from the desodiation process from compensation of sodium deficiencies in the NaTi2(PO4)3 by extra sodium from the CMC binder. When the binder comprises CMC and a styrene butadiene rubber (SBR) additive, the electrode delivers significantly better voltammetric and galvanostatic electrochemical response with a specific capacity of ∼120 mAh g−1 with capacity retention of 90.5% for 500 cycles at 0.2 C (1 C = 133 mAh g−1), and ∼54 mAh g−1 at 20 C. The durability of the electrode during cycling and the stability of the redox processes ensures a higher capacity, longer cycle life electrode which is important for sustainable materials development for Na-ion technologies.
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    Recent developments in monitoring and modelling airborne pollen, a review
    (Taylor & Francis Group, 2020-07-07) Maya-Manzano, Jose María; Smith, Matt; Markey, Emma; Hourihane Clancy, Jerry; Sodeau, John; O´Connor, David J.; Environmental Protection Agency; Met Éireann; Irish Research Council
    Public awareness of the rising importance of allergies and other respiratory diseases has led to increased scientific effort to accurately and rapidly monitor and predict pollen, fungal spores and other bioaerosols in our atmosphere. An important driving force for the increased social and scientific concern is the realisation that climate change will increasingly have an impact on worldwide bioaerosol distributions and subsequent human health. In this review we examine new developments in monitoring of atmospheric pollen as well as observation and source-orientated modelling techniques. The results of a Scopus® search for scientific publications conducted with the terms ‘Pollen allergy’ and ‘Pollen forecast’ included in the title, abstract or keywords show that the number of such articles published has increased year on year. The 12 most important allergenic pollen taxa in Europe as defined by COST Action ES0603 were ranked in terms of the most ‘popular’ for model-based forecasting and for forecasting method used. Betula, Poaceae and Ambrosia are the most forecast taxa. Traditional regression and phenological models (including temperature sum and chilling models) are the most used modelling methods, but it is notable that there are a large number of new modelling techniques being explored. In particular, it appears that Machine Learning techniques have become more popular and led to better results than more traditional observation-orientated models such as regression and time-series analyses.
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    Many facets of photonic crystals: from optics and sensors to energy storage and photocatalysis
    (Wiley, 2022-12-05) Lonergan, Alex; O'Dwyer, Colm; Irish Research Council
    The ability to selectively redirect specific wavelengths of light has attracted a lot attention for photonic crystal materials. Presently, there is a wealth of research relating to the fabrication and application of photonic crystal materials. There are a number of structures that fall into the category of a photonic crystal; 1D, 2D, and 3D ordered structures can qualify as a photonic crystal, provided there exists ordered repeating lattices of dielectric material with a sufficient refractive index contrast. The optical responses of these structures, namely the associated photonic bandgap or stopband, are of particular interest for any application involving light. The sensitivity of the photonic bandgap to changes in lattice size or refractive index composition creates the possibility for accurate optical sensors. Optical phenomena involving reduced group velocity at wavelengths on the edge of the photonic bandgap are commonly exploited for photocatalytic applications. The inherent reflectivity of the photonic bandgap has created applications in optical waveguides or as solar cell reflector layers. There are countless examples of research attempting to exploit these facets of photonic crystal behavior for improved material design. Here, the role of photonic crystals is reviewed across a wide variety of disciplines; cataloging the ways in which these structures have enhanced specific applications. Particular emphasis is placed on providing an understanding of the specific function of the tunable optical response in photonic crystals in relation to their application.
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    Methods-Ampero-Coulometry: a new technique for understanding lithium-sulfur electrochemistry
    (IOP Science, 2023-03) Gulzar, Umair; Lonergan, Alex; Egorov, Vladimir; Zhang, Yan; Grant, Alex; Carroll, Aoife; O'Dwyer, Colm; Irish Research Council; Horizon 2020; European Regional Development Fund; Enterprise Ireland
    Despite limited commercial success, lithium sulfur technology (LST) is still far from competing existing Li-ion technology. One of the main reasons hindering the success of LST is the complexity of lithium-sulfur chemistry during electrochemical charging and discharging. Dissolution of sulfur species in the electrolyte solution exacerbates the difficulties of this system. Therefore, a comprehensive understanding of sulfur species and their kinetics during charge/discharge process is paramount for a high-performance lithium-sulfur battery. We present a new technique we refer to as Ampero-Coulometry, which takes the chronoamperometric (galvanostatic) charge-discharge curves and mathematically transforms them to a series of curves that reveal the cation diffusional rate inside carbon-sulfur porous electrodes at different states of charge/capacity. This technique allowed us to track the overall Li+ ion diffusional rate inside a Li-S cell over a complete state of discharge. As dissolution of sulfur species and their interplay inside a porous sulfur electrode has a significant role in limiting Li-S battery capacity, and method allows correlation between the known mechanism of polysulfide dissolution, the kinetics of a sulfur electrode, and its response.
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    Real-time nondestructive methods for examining battery electrode materials
    (American Institute of Physics, 2023-03) Grant, Alex; O'Dwyer, Colm; Irish Research Council
    With the importance of Li-ion and emerging alternative batteries to our electric future, predicting new sustainable materials, electrolytes, and complete cells that safely provide high performance, long life, and energy dense capability is critically important. Understanding the interface, the microstructure of materials, and the nature of electrolytes and factors that affect or limit long-term performance is key to new battery chemistries, cell form factors, and alternative materials. The electrochemical processes `that cause these changes are also difficult to probe because of their metastability and lifetimes, which can be of nanosecond to sub-nanosecond time domains. Consequently, developing and adapting high-resolution, nondestructive methods to capture these processes proves challenging, requiring state-of-the-art techniques. Recent progress is very promising, where optical spectroscopies, synchrotron radiation techniques, and energy-specific atom probe tomography and microscopy methods are just some of the approaches that are unraveling the true internal behavior of battery cells in real-time. In this review, we overview many of the most promising nondestructive methods developed in recent years to assess battery material properties, interfaces, processes, and reactions under operando conditions similar in electrodes and full cells.