In this work, we report a highly efficient organic polymer nano-photocatalyst for light driven proton reduction. The system renders an initial rate of hydrogen evolution up to 50 plus or minus 0.5 ...mmol g-1 h-1, which is the fastest rate among all other reported organic photocatalysts. We also experimentally and theoretically prove that the nitrogen centre of the benzothiadiazole unit plays a crucial role in the photocatalysis and that the Pdots structure holds a close to ideal geometry to enhance the photocatalysis.
For the first time, organic semiconducting polymer dots (Pdots) based on poly(9,9′‐dioctylfluorenyl‐2,7‐diyl)‐co‐(1,4‐benzo‐{2,1′,3} thiadiazole) (PFBT) and polystyrene grafting with ...carboxyl‐group‐functionalized ethylene oxide (PS‐PEG‐COOH) are introduced as a photocatalyst towards visible‐light‐driven hydrogen generation in a completely organic solvent‐free system. With these organic Pdots as the photocatalyst, an impressive initial rate constant of 8.3 mmol h−1 g−1 was obtained for visible‐light‐driven hydrogen production, which is 5‐orders of magnitude higher than that of pristine PFBT polymer under the same catalytic conditions. Detailed kinetics studies suggest that the productive electron transfer quench of the excited state of Pdots by an electron donor is about 40 %. More importantly, we also found that the Pdots can tolerate oxygen during catalysis, which is crucial for further application of this material for light‐driven water splitting.
Organic polymer dots were used as a photocatalyst for visible‐light‐driven hydrogen generation for the first time and showed impressive activity with an initial hydrogen generation rate of 8.3 mmol h−1 g−1 without the assistance of any co‐catalysts. Do=donor.
Digitally printed stretchable electronics: a review Fernandes, Daniel Félix; Majidi, Carmel; Tavakoli, Mahmoud
Journal of materials chemistry. C, Materials for optical and electronic devices,
2019, Letnik:
7, Številka:
45
Journal Article
Recenzirano
Stretchable electronics are becoming an important branch in the field of electronics, with a rapidly growing number of studies on highly deformable circuits that can handle large tensile strains ...without losing electronic functionality. However, as the field continues to advance, a variety of manufacturing approaches must be explored so that these circuits can be produced in a rapid, precise, repeatable, inexpensive, and high-volume manner. Even in cases where methods from conventional printed circuit board (PCB) manufacturing are used, these techniques must be significantly modified in order to process the soft materials and fluids that are unique to stretchable electronic architectures. Digital printing methods such as Inkjet printing, 3D printing and laser ablation are especially attractive since they can be automated and eliminate the need for a stencil, mask or clean-room lithography. This article reviews recent advances in digital fabrication of stretchable circuits using either additive techniques, that allow direct printing of certain materials with a determined shape, or subtractive methods, in which the desired pattern is obtained by selectively removing parts of a greater film. For most of the materials used in stretchable electronics, these fabrication methods can be simple to implement, low cost, scalable over large areas, compatible with a broad variety of materials and have a size resolution that is comparable to conventional PCB manufacturing.
Digital printing of stretchable electronics is reviewed. Multiple technologies and materials, like liquid metals and composites, are addressed.
Hydrated electrons are important in radiation chemistry and charge-transfer reactions, with applications that include chemical damage of DNA, catalysis, and signaling. Conventionally, hydrated ...electrons are produced by pulsed radiolysis, sonolysis, two-ultraviolet-photon laser excitation of liquid water, or photodetachment of suitable electron donors. Here we report a method for the generation of hydrated electrons via single-visible-photon excitation of localized surface plasmon resonances (LSPRs) of supported sub-3 nm copper nanoparticles in contact with water. Only excitations at the LSPR maximum resulted in the formation of hydrated electrons, suggesting that plasmon excitation plays a crucial role in promoting electron transfer from the nanoparticle into the solution. The reactivity of the hydrated electrons was confirmed via proton reduction and concomitant H2 evolution in the presence of a Ru/TiO2 catalyst.
A bi-phasic ternary Ag–In–Ga ink that demonstrates high electrical conductivity, extreme stretchability, and low electromechanical gauge factor (GF) is introduced. Unlike popular liquid metal alloys ...such as eutectic gallium–indium (EGaIn), this ink is easily printable and nonsmearing and bonds strongly to a variety of substrates. Using this ink and a simple extrusion printer, the ability to perform direct writing of ultrathin, multi-layer circuits that are highly stretchable (max. strain >600%), have excellent conductivity (7.02 × 105 S m–1), and exhibit only a modest GF (0.9) related to the ratio of percent increase in trace resistance with mechanical strain is demonstrated. The ink is synthesized by mixing optimized quantities of EGaIn, Ag microflakes, and styrene-isoprene block copolymers, which functions as a hyperelastic binder. When compared to the same composite without EGaIn, the Ag–In–Ga ink shows over 1 order of magnitude larger conductivity, up to ∼27× lower GF, and ∼5× greater maximum stretchability. No significant change over the resistance of the ink was observed after 1000 strain cycles. Microscopic analysis shows that mixing EGaIn and Ag microflakes promotes the formation of AgIn2 microparticles, resulting in a cohesive bi-phasic ink. The ink can be sintered at room temperature, making it compatible with many heat-sensitive substrates. Additionally, utilizing a simple commercial extrusion based printer, the ability to perform stencil-free, digital printing of multi-layer stretchable circuits over various substrates, including medical wound-dressing adhesives, is demonstrated for the first time.
The purpose of this tutorial article is to provide a brief update on the advances available for laser-induced breakdown spectroscopy (LIBS), focusing broad experimental and instrumental ...possibilities. Due to the inherent versatility of LIBS, this technique can be elegantly applied to various applications. However, during the method development one should have prior knowledge about its analytical limitations in order to obtain reliable results. In the present review, we summarize key analytical variables required for proper sample treatment, analytical signal enhancement, data processing, qualitative and quantitative approaches as well as recent research and developments using LIBS. Remarkable analytical advances have recently been proposed for LIBS and raised its analytical performance to a level never reached before. Most prominent perhaps, have been the development of many nontraditional calibration approaches based on transition atomic energies (emission wavelengths), the use of a single standard for calibration, increase of the ablated sample mass (accumulated laser pulses), and even overcoming severe LIBS problems such as the matrix effects.
We apply the Business Cycle Accounting framework to the COVID-19 recession in the Euro Area and the United States. We conclude that the efficiency wedge had the most important role in the Euro Area, ...followed by the labor and investment wedges. In the United States, the labor wedge was the most crucial, with the investment wedge taking a second place. We present hypotheses, supported by our theoretical framework, for the dichotomy of the role of the efficiency wedge between the studied regions.
The cortical bone that forms the structure of the cochlea, part of the osseous labyrinth of the inner ear, is now one of the most frequently used skeletal elements in analyses of human ancient DNA. ...However, there is currently no published, standardized method for its sampling. This protocol describes the preparation of bone powder from the cochlea of fragmented skulls in which the petrous pyramid of the temporal bone is accessible. Using a systematic process of bone removal based on distinct anatomical landmarks and the identification of relevant morphological features, a petrous pyramid is cleaned with a sandblaster, and the cochlea is located, isolated, and reduced to a homogeneous bone powder. All steps are carried out in dedicated ancient DNA facilities, thus reducing the introduction of contamination. This protocol requires an understanding of ancient DNA clean-room procedures and basic knowledge of petrous pyramid anatomy. In 50-65 min, it results in bone powder with endogenous DNA yields that can exceed those from teeth and other bones by up to two orders of magnitude. Compared with drilling methods, this method facilitates a more precise targeting of the cochlea, allows the user to visually inspect the cochlea and remove any residual sediment before the generation of bone powder, and confines the damage to the inner ear region and surface of the petrous portion of fragmentary crania.
Policy makers have embraced financial education as a necessary antidote to the increasing complexity of consumers' financial decisions over the last generation. We conduct a meta-analysis of the ...relationship of financial literacy and of financial education to financial behaviors in 168 papers covering 201 prior studies. We find that interventions to improve financial literacy explain only 0.1% of the variance in financial behaviors studied, with weaker effects in low-income samples. Like other education, financial education decays over time; even large interventions with many hours of instruction have negligible effects on behavior 20 months or more from the time of intervention. Correlational studies that measure financial literacy find stronger associations with financial behaviors. We conduct three empirical studies, and we find that the partial effects of financial literacy diminish dramatically when one controls for psychological traits that have been omitted in prior research or when one uses an instrument for financial literacy to control for omitted variables. Financial education as studied to date has serious limitations that have been masked by the apparently larger effects in correlational studies. We envisage a reduced role for financial education that is not elaborated or acted upon soon afterward. We suggest a real but narrower role for "just-in-time" financial education tied to specific behaviors it intends to help. We conclude with a discussion of the characteristics of behaviors that might affect the policy maker's mix of financial education, choice architecture, and regulation as tools to help consumer financial behavior.
This paper was accepted by Uri Gneezy, behavioral economics.
The efficient conversion of light energy into chemical energy is key for sustainable human development. Several photocatalytic systems based on photovoltaic electrolysis have been used to produce ...hydrogen via water reduction. However, in such devices, light harvesting and proton reduction are carried separately, showing quantum efficiency of about 10-12%. Here, we report a nano-hybrid photocatalytic assembly that enables concomitant reductive hydrogen production and pollutant oxidation with solar-to-fuel efficiencies up to 20%. The modular architecture of this plasmonic material allows the fine-tuning of its photocatalytic properties by simple manipulation of a reduced number of basic components.
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