Chemical and electrochemical synthesis and deposition of chalcogenides from room temperature ionic liquids

Room temperature electrochemical methods to deposit thin films of chalcogenide glasses.Board of Regents, University of Texas Syste

Chemical and electrochemical synthesis and deposition of chalcogenides from room temperature ionic liquids

Room temperature electrochemical methods to deposit thin films of chalcogenide glasses.Board of Regents, University of Texas Syste

Confinement-controlled Water Engenders High Energy Density Electrochemical-double-layer Capacitance

The renewable energy sector critically needs low-cost and environmentally neutral energy storage solutions throughout the entire device life cycle. However, the limited performance of standard water-based electrochemical systems prevents their use in certain applications. Meanwhile, recent fundamental studies revealed dielectric anomalies of water near solid-liquid interfaces of carbon-based nanomaterials. In contrast to the bulk water properties, these anomalies of water under nano-confinement and in the presence of electric fields have not yet been understood and used. Here, we experimentally study the ability of the interfacial water layer to engender and store charge in electrochemical double-layer capacitance. We demonstrate the first prototype of a water-only membrane-electrode assembly. The prototype exhibits characteristics comparable to existing batteries and supercapacitors without using electrolytes as ionic carriers. The results provide the impetus for the development of high-energy-density electrochemical double-layer capacitors and open up other avenues for ecologically-neutral batteries, fuel cells, and nanofluidic devices

Water electrolysis on La1−xSrxCoO3−δ perovskite electrocatalysts

Perovskite oxides are attractive candidates as catalysts for the electrolysis of water in alkaline energy storage and conversion systems. However, the rational design of active catalysts has been hampered by the lack of understanding of the mechanism of water electrolysis on perovskite surfaces. Key parameters that have been overlooked include the role of oxygen vacancies, B–O bond covalency, and redox activity of lattice oxygen species. Here we present a series of cobaltite perovskites where the covalency of the Co–O bond and the concentration of oxygen vacancies are controlled through Sr[superscript 2+] substitution into La[scubscript 1−x]Sr[scubscript x]CoO[scubscript 3−δ]. We attempt to rationalize the high activities of La[scubscript 1−x]Sr[scubscript x]CoO[scubscript 3−δ] through the electronic structure and participation of lattice oxygen in the mechanism of water electrolysis as revealed through ab initio modelling. Using this approach, we report a material, SrCoO[subscript 2.7], with a high, room temperature-specific activity and mass activity towards alkaline water electrolysis.Robert A. Welch Foundation (grant F-1529)Robert A. Welch Foundation (grant F-1319)MIT Skoltech Initiative (Massachusetts Institute of Technology. Center for Electrochemical Energy Storage

The Good, the Bad, and the Ugly: Agonistic Behaviour in Juvenile Crocodilians

We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5–15 seconds), and occurred between 1600–2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae; and, side head striking combined with tail wagging by C. porosus. The two long-snouted species (C. johnstoni and G. gangeticus) avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae) appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes

Factors affecting how children hear words and their relation to reading ability

Sensitivity to lexical stress has received attention recently as a predictor of reading skill. Six experiments explored the relationship between the reader's ability to process stress in spoken disyllabic nouns and verbs. In Experiments 1 and 2, adults and children identified disyllabic nouns and verbs, each involving trochaic and iambic instances, in "yes/no" and "go/nogo" auditory lexical decision tasks. The results showed that they processed lexical stress in the same manner, across both tasks, except children were slower. In Experiment 3, when children were presented with only iambic verbs and trochaic nouns in a verb/noun categorization task, poor readers were faster than good readers. Whereas Experiments 1 to 3 involved the presentation of a single spoken word on each trial, Experiments 4 to 6 all involved the presentation of spoken word pairs differing only in terms of stress (iambic verbs and trochaic nouns; e.g., reWARD and REward). Experiment 4 required children to decide whether the noun (or verb on 50% of trials) was first or last in the pair. Good and poor readers both showed no difference in response latencies, but did better at categorising iambic items. However, in Experiment 5, only good readers showed differences between identity (same) and contrastive (different) items in a same/different task. In Experiment 6, poor readers attended more to suprasegmentals, whereas good readers appeared to process the items at the segmental level in auditory priming lexical decision. Overall, the results showed that poor readers appear to attend more to acoustic/phonetic information in spoken word recognition, whereas the good readers attend to segmental information at the lexical level in spoken word recognition

Preparation and catalytic evaluation of ruthenium–nickel dendrimer encapsulated nanoparticles via intradendrimer redox displacement of nickel nanoparticles

Ru and Ru_xNi_(30) dendrimer encapsulated nanoparticles (DENs) were synthesized using a redox-displacement method. DEN catalytic activity for the reduction of p-nitrophenol was evaluated and found to be dependent on the ratio of metals present

Confinement-Controlled Water Engenders Unusually High Electrochemical Capacitance

The electrodynamics of nanoconfined water have been shown to change dramatically compared to bulk water, opening room for safe electrochemical systems. We demonstrate a nanofluidic “water-only” battery that exploits anomalously high electrolytic properties of pure water at firm confinement. The device consists of a membrane electrode assembly of carbon-based nanomaterials, forming continuously interconnected water-filled nanochannels between the separator and electrodes. The efficiency of the cell in the 1–100 nm pore size range shows a maximum energy density at 3 nm, challenging the region of the current metal-ion batteries. Our results establish the electrodynamic fundamentals of nanoconfined water and pave the way for low-cost and inherently safe energy storage solutions that are much needed in the renewable energy sector

Stabilizing perovskite solar cells with modified indium oxide electron transport layer

Despite the impressive progress, the perovskite solar cells are still under the stage of laboratory research, mainly because of their inferior operational stability. To improve the device lifetime, one of the most important strategies is to eliminate the undesirable side reactions between the functional layers. In this study, we present the thermal oxidation method to yield high-quality pristine and modified indium oxide films applied as efficient electron transport layers (ETLs) for perovskite cells in a planar n-i-p configuration. The cells incorporating In2O3 as ETL material can deliver comparable efficiencies with the reference SnO2- based devices while showing much superior operational stability. We attributed the observed stabilizing effect of indium oxide to its reduced chemical activity at the interface with the perovskite absorber layer. In particular, In2O3 can hardly oxidize I- to molecular iodine on the contrary to SnO2 and TiO2 known for their photocatalytic activity. We believe that this study may provide researchers with general guidelines to develop a large variety of ETL materials for efficient yet stable perovskite cells