We argue that conservatism improves investment efficiency. In particular, we predict that it resolves debt-equity conflicts, facilitating a firm׳s access to debt financing and limiting ...underinvestment. This permits the financing of prudent investments that otherwise might not be pursued. Our empirical results confirm these predictions. We find that more conservative firms invest more and issue more debt in settings prone to underinvestment and that these effects are more pronounced in firms characterized by greater information asymmetries. We also find that conservatism is associated with reduced overinvestment, even for opaque investments such as research and development.
•Conservatism mitigates under-investment as it facilitates access to debt financing.•Conservatism facilitates financing projects that otherwise might not be pursued.•The effect of conservatism is more pronounced when information asymmetry is high.•Conservatism also reduces over-investment, even for low visibility investments.•The results are robust to controls for governance and accounting reporting quality.
Current colloidal synthesis methods for CdSe nanoplatelets (NPLs) routinely yield samples that emit, in discrete steps, from 460 to 550 nm. A significant challenge lies with obtaining thicker NPLs, ...to further widen the emission range. This is at present typically achieved via colloidal atomic layer deposition onto CdSe cores, or by synthesizing NPL core/shell structures. Here, we demonstrate a novel reaction scheme, where we start from 4.5 monolayer (ML) NPLs and increase the thickness in a two-step reaction that switches from 2D to 3D growth. The key feature is the enhancement of the growth rate of basal facets by the addition of CdCl2, resulting in a series of nearly monodisperse CdSe NPLs with thicknesses between 5.5 and 8.5 ML. Optical characterization yielded emission peaks from 554 nm up to 625 nm with a line width (fwhm) of 9–13 nm, making them one of the narrowest colloidal nanocrystal emitters currently available in this spectral range. The NPLs maintained a short emission lifetime of 5–11 ns. Finally, due to the increased red shift of the NPL band edge photoluminescence excitation spectra revealed several high-energy peaks. Calculation of the NPL band structure allowed us to identify these excited-state transitions, and spectral shifts are consistent with a significant mixing of light and split-off hole states. Clearly, chloride ions can add a new degree of freedom to the growth of 2D colloidal nanocrystals, yielding new insights into both the NPL synthesis as well as their optoelectronic properties.
Purpose
Nowadays, the electric vehicle is one of the most promising alternatives for sustainable transportation. However, the battery, which is one of the most important components, is the main ...contributor to environmental impact and faces recycling issues. In order to reduce the carbon footprint and to minimize the overall recycling processes, this paper introduces the concept of re-use of electric vehicle batteries, analyzing some possible second-life applications.
Methods
First, the boundaries of the life cycle assessment of an electric vehicle are defined, considering the use of the battery in a second-life application. To perform the study, we present eight different scenarios for the second-life application. For each case, the energy, the efficiency, and the lifetime of the battery are calculated. Additionally, and based on the global warming potential, the environmental impact of the electric vehicle and its battery on a second-life application is determined for each scenario. Finally, an environmentally focused discussion on battery electrodes and research trends is presented.
Results and discussion
For the selected scenarios, the second life of the battery varies from 8 to 20 years depending on the application and the requirements. It has been observed that the batteries connected to the electricity grid for energy arbitrage storage have the highest impact per provided kilowatt hour. On the contrary, the environmental benefit comes from applications working with renewable energy sources and presenting a longer lifetime. We pointed out that a correlation between cycling conditions and degradation mechanisms of the electrode materials is compulsory for proper use of the electric vehicle battery in a second-life application.
Conclusions
To limit the environmental impact, batteries should be associated with renewable energy sources in stationary applications. However, it is more profitable to re-use Li-ion batteries than to use new lead-acid batteries. Although many batteries applied for electric vehicles use graphite-based anodes, the latter may not be the most suitable for the second-life application. A better understanding of Li-ion battery degradation during the second-life application is required for the different existing chemistries.
The miniaturization of energy storage units is pivotal for the development of next‐generation portable electronic devices. Micro‐supercapacitors (MSCs) hold great potential to work as on‐chip ...micro‐power sources and energy storage units complementing batteries and energy harvester systems. Scalable production of supercapacitor materials with cost‐effective and high‐throughput processing methods is crucial for the widespread application of MSCs. Here, wet‐jet milling exfoliation of graphite is reported to scale up the production of graphene as a supercapacitor material. The formulation of aqueous/alcohol‐based graphene inks allows metal‐free, flexible MSCs to be screen‐printed. These MSCs exhibit areal capacitance (Careal) values up to 1.324 mF cm−2 (5.296 mF cm−2 for a single electrode), corresponding to an outstanding volumetric capacitance (Cvol) of 0.490 F cm−3 (1.961 F cm−3 for a single electrode). The screen‐printed MSCs can operate up to a power density above 20 mW cm−2 at an energy density of 0.064 µWh cm−2. The devices exhibit excellent cycling stability over charge–discharge cycling (10 000 cycles), bending cycling (100 cycles at a bending radius of 1 cm) and folding (up to angles of 180°). Moreover, ethylene vinyl acetate‐encapsulated MSCs retain their electrochemical properties after a home‐laundry cycle, providing waterproof and washable properties for prospective application in wearable electronics.
Single‐/few‐layer graphene flakes, produced via scalable wet‐jet milling exfoliation of graphite, are used as the active material for micro‐supercapacitors (MSCs). The formulation of aqueous‐alcohol graphene inks, as well as the addition of carbon nanotubes, allows for the interdigitated structure to be screen‐printed on plastic substrates for metal‐free, flexible, solid‐state, and washable MSCs with high areal performance.
The design of cost-effective and efficient electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is pivotal for the molecular hydrogen (H2) production from ...electrochemical water splitting as a future energy source. Herein, we show that the hybridization between multiple HER- and OER-active components is effective for the design and realization of bifunctional electrocatalysts for universal water splitting, i.e., in both acidic and alkaline media. Our strategy relies on the production and characterization of MoSe2 holey flake:Mo2C ball hybrids supported by single-walled carbon nanotube (SWCNT) electrocatalysts. Flakes of MoSe2 are produced through hydrogen peroxide (H2O2)-aided liquid phase exfoliation (LPE), which promotes both the exfoliation of the materials and the formation of nanopores in the flakes via chemical etching. The amount of H2O2 in the solvent used for the exfoliation process is optimized to obtain ideal high ratio between edge and basal sites ratio, i.e., high-number of electrocatalytic sites. The hybridization of MoSe2 flakes with commercial ball-like shaped Mo2C crystals facilitates the Volmer reaction, which works in both acidic and alkaline media. In addition, the electrochemical coupling between SWCNTs (as support) and MoSe2:Mo2C hybrids synergistically enhances both HER- and OER-activity of the native components, reaching high η10 in acidic and alkaline media (0.049 and 0.089 V for HER in 0.5 M H2SO4 and 1 M KOH, respectively; 0.197 and 0.241 V for OER in 0.5 M H2SO4 and 1 M KOH, respectively). The exploitation of the synergistic effects occurring between multicomponent electrocatalysts, coupled with the production of the electrocatalysts themselves through scalable and cost-effective solution-processed manufacturing techniques, is promising to scale-up the production of H2 via efficient water splitting for the future energy portfolio.
Electric vehicles are considered the most promising alternative to internal combustion engine vehicles towards a cleaner transportation sector. Having null tailpipe emissions, electric vehicles ...contribute to fight localized pollution, which is particularly important in overpopulated urban areas. However, the electric vehicle implies greenhouse gas emissions related to its production and to the electricity generation needed to charge its batteries. This study focuses the analysis on how the electric vehicle emissions vary when compared to internal combustion engine vehicles, depending on the electric power plant fleet and the efficiency during the use-phase. For this to be done, the Global Warming Potential (GWP) associated to the electricity generation on the electric vehicle most selling European countries are calculated. Similarly, electric vehicle's use-phase energy efficiency is calculated under a wide range of driving conditions using the Monte Carlo method. The results from energy production and energy use-phases are compared to the GWP calculated for internal combustion engine vehicles for six different driving cycles, to obtain the threshold values for which electric vehicles provide GWP reduction. These threshold values are then matched with the current electricity power plant fleet and the electric vehicle promotion incentives of the European countries considered in the study, showing that some countries (e.g. France or Norway) are better-suited for electric vehicles adoption, while countries like Spain or Portugal should boost electric vehicle promotion policies. Furthermore, other countries in Europe, such as Germany or the UK that are doing an effort on decarbonizing their power plant fleet, do not offer immediate greenhouse gas emission reductions for the uptake of electric vehicles instead of conventional cars.
•Comparison of the global warming potential of electric and conventional vehicles.•A Monte Carlo analysis of electric vehicle energy consumption is performed.•CO2 emissions analysis from electricity mix of several European countries.•The effect of the electricity generation on Electric vehicle emissions is analyzed.•Renewable promotion policies and electric vehicle incentives are not always coupled.
Layered semiconductors of the IIIA–VIA group have attracted considerable attention in (opto)electronic applications thanks to their atomically thin structures and their thickness‐dependent optical ...and electronic properties, which promise ultrafast response and high sensitivity. In particular, 2D indium selenide (InSe) has emerged as a promising candidate for the realization of thin‐film field effect transistors and phototransistors due to its high intrinsic mobility (>102 cm2 V−1 s−1) and the direct optical transitions in an energy range suitable for visible and near‐infrared light detection. A key requirement for the exploitation of large‐scale (opto)electronic applications relies on the development of low‐cost and industrially relevant 2D material production processes, such as liquid phase exfoliation, combined with the availability of high‐throughput device fabrication methods. Here, a β polymorph of indium selenide (β‐InSe) is exfoliated in isopropanol and spray‐coated InSe‐based photodetectors are demonstrated, exhibiting high responsivity to visible light (maximum value of 274 A W−1 under blue excitation 455 nm) and fast response time (15 ms). The devices show a gate‐dependent conduction with an n‐channel transistor behavior. Overall, this study establishes that liquid phase exfoliated β‐InSe is a valid candidate for printed high‐performance photodetectors, which is critical for the development of industrial‐scale 2D material‐based optoelectronic devices.
Spray coating interdigitated microelectrodes with an ink consisting of few layer InSe flakes, obtained by liquid phase exfoliation, produce highly sensitive and fast photodetectors, which respond to visible and NIR light. This work provides an industrially scalable and cost‐effective approach for the production of high‐performance optoelectronic devices.
Gallium selenide (GaSe) is a layered compound, which has been exploited in nonlinear optical applications and photodetectors due to its anisotropic structure and pseudodirect optical gap. Theoretical ...studies predict that its 2D form is a potential photocatalyst for water splitting reactions. Herein, the photoelectrochemical (PEC) characterization of GaSe nanoflakes (single‐/few‐layer flakes), produced via liquid phase exfoliation, for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both acidic and alkaline media is reported. In 0.5 m H2SO4, the GaSe photoelectrodes display the best PEC performance, corresponding to a ratiometric power‐saved metric for HER (Φsaved,HER) of 0.09% and a ratiometric power‐saved metric for OER (Φsaved,OER) of 0.25%. When used as PEC‐type photodetectors, GaSe photoelectrodes show a responsivity of ≈0.16 A W−1 upon 455 nm illumination at a light intensity of 63.5 µW cm−2 and applied potential of −0.3 V versus reversible hydrogen electrode (RHE). Stability tests of GaSe photodetectors demonstrated a durable operation over tens of cathodic linear sweep voltammetry scans in 0.5 m H2SO4 for HER. In contrast, degradation of photoelectrodes occurred in both alkaline and anodic operation due to the highly oxidizing environment and O2‐induced (photo)oxidation effects. The results provide new insight into the PEC properties of GaSe nanoflakes for their exploitation in photoelectrocatalysis, PEC‐type photodetectors, and (bio)sensors.
Two‐dimensional group‐III monochalcogenides, namely, gallium selenide (GaSe) nanoflakes, are produced and processed by scalable methods (liquid‐phase exfoliation and spray coating film deposition) to be directly exploited for photoelectrochemical water splitting and photoelectrochemical‐type photodetectors.
The exfoliation of layered magnetic materials generates atomically thin flakes characterized by an ultrahigh surface sensitivity, which makes their magnetic properties tunable via external stimuli, ...such as electrostatic gating and proximity effects. Another powerful approach to engineer magnetic materials is molecular functionalization, generating hybrid interfaces with tailored magnetic interactions, called spinterfaces. However, spinterface effects have not yet been explored on layered magnetic materials. Here, the emergence of spinterface effects is demonstrated at the interface between flakes of the prototypical layered magnetic metal Fe3GeTe2 and thin films of Co‐phthalocyanine. Magnetotransport measurements show that the molecular layer induces a magnetic exchange bias in Fe3GeTe2, indicating that the unpaired spins in Co‐phthalocyanine develop antiferromagnetic ordering and pin the magnetization reversal of Fe3GeTe2 via magnetic proximity. The effect is strongest for a Fe3GeTe2 thickness of 20 nm, for which the exchange bias field reaches −840 Oe at 10 K and is measurable up to ≈110 K. This value compares very favorably with previous exchange bias fields reported for Fe3GeTe2 in all‐inorganic van der Waals heterostructures, demonstrating the potential of molecular functionalization to tailor the magnetism of van der Waals layered materials.
Spinterface effects are demonstrated in a hybrid van der Waals heterostructure composed of a CoPc film interfaced with a layered ferromagnet Fe3GeTe2. The interface interactions introduce an exchange bias field in Fe3GeTe2, which is among the strongest reported for layered magnetic materials. The results demonstrate the potential of molecular functionalization for tailoring the magnetic properties of layered materials.
Objective
To evaluate body composition, nutritional status through food selectivity and degree of inadequate intake, and mealtime behavior in children with autism spectrum disorder (ASD) compared to ...neurotypical children.
Method
A cross‐sectional case–control study was carried out in 144 children (N = 55 with ASD; N = 91 with neurotypical children) between 6 and 18 years of age. Body composition, nutritional intake, food consumption frequency (FFQ), and mealtime behavior were evaluated.
Results
Results showed a greater presence of children with a low weight (18.4% ASD vs. 3.20% comparison group) and obesity (16.3% ASD vs. 8.6% comparison group) in the ASD group for body mass index (BMI) categories (p = .003; number needed to take NNT = 8.07). The presence of obesity in ASD children compared to the comparison group was even higher when considering the fat component (47.5% ASD vs. 19.4% comparison group, p = .002; NNT = 10.3). ASD children had greater intake inadequacy (50% ASD vs. 22% comparison group, p = .014; NNT = 3.58), high food selectivity by FFQ (60.6% ASD vs. 37.9% comparison group, p < .037; NNT = 4.41), and more eating problems (food rejection, limited variety, disruptive behavior), compared to neurotypical children (p = .001).
Conclusion
Children with ASD showed an unbalanced body composition toward both underweight and obesity, a greater degree of inadequate intake, high food selectivity as indicated by their consumption frequency, and more disturbed eating behavior than children with neurotypical development. We suggest monitoring nutritional inadequacies and implementing nutritional strategies to expand the variety of foods children with ASD consume.
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