1,721,540 research outputs found
An ultralight and flexible sodium titanate nanowire aerogel with superior sodium storage
No full textAn ultralight, conductive, and flexible 3D assembly of a metal oxide nanowire aerogel as an electrode for energy storage devices without additives and typically inconvenient flexible supported-substrates remains a challenge. Herein, we report a new 3D highly ordered layer-by-layer stacking sodium titanate@reduced graphene oxide core-shell (NTO@GCS) nanowire aerogel that has an ultra-high aspect ratio with a diameter of 30-50 nm and typical length up to 100 μm for a new class of convenient sodium-ion battery (SIB) anodes. The formation mechanism of the unique 3D NTO nanowire aerogel, the precursor of the NTO@GCS aerogel, was carefully proposed, demonstrating that the key challenge for this synthesis strategy was to form a stable and homogeneous ultrafine NTO nanotube gel suspension. In addition, for high performance sodium-ion storage, reduced graphene oxides (rGOs) were introduced into the NTO aerogel backbone. The critical role of the graphene structure between the NTO nanowires and rGO sheets in Na+ storage was systematically investigated. Compared to the 3D pristine NTO aerogel and 3D NTO nanowires on graphene sheet paper, the 3D interconnected NTO-GCS aerogel electrode facilitated rapid ion/electrolyte transportation, resulting in remarkably enhanced Na+ storage with a reversible capacity of 240 mA h g-1 at 0.2C and durable cycling stability after 4900 cycles at a rate of 2 and 4C with nearly 100% coulombic efficiency. © 2018 The Royal Society of Chemistr
Supplemental material for Reported immigration and medical coercion among immigrants referred to a cultural consultation service
No full textSupplemental Material for Reported immigration and medical coercion among immigrants referred to a cultural consultation service by Don Quang Tran McGill University Andrew G. Ryder Concordia University G. Eric Jarvis in Transcultural Psychiatry</p
Supplemental Material - Does Institutional Quality Matter for Foreign Direct Investment and Human Development?
No full textSupplemental Material for Does Institutional Quality Matter for Foreign Direct Investment and Human Development? by Van Thi Cam Ha, Tinh Doan, Mark J. Holmes, and Tuyen Quang Tran in Evaluation Review</p
Anion-Cation Double Substitution in Transition Metal Dichalcogenide to Accelerate Water Dissociation Kinetic for Electrocatalysis
No full textUntil now, many works have shown that the hydrogen evolution reaction (HER) performance can be improved by anion or cation substitution into the crystal lattice of pyrite-structure materials. However, the synergistic effects of anion-cation double substitution for overall enhancement of the catalytic activity remains questionable. Here, the simultaneous incorporation of vanadium and phosphorus into the CoS2 moiety for preparing 3D mesoporous cubic pyrite-metal Co1-xVxSP is presented. It is demonstrated that the higher catalytic activity of CoS2 after V incorporation can be primarily attributed to abundance active sites, whereas P substitution is responsible for improving HER kinetics and intrinsic catalyst. Interestingly, due to the synergistic effect of P-V double substitution, the 3D Co1-xVxSP shows superior electrocatalysis toward the HER with a very small overpotential of 55 mV at 10 mA cm(-2), a small Tafel slope of 50 mV dec(-1), and a high turnover frequency of 0.45 H-2 s(-1) at 10 mA cm(-2), which is very close to commercial 20% Pt/C. Density functional theory calculation reveals that the superior catalytic activity of the 3D Co1-xVxSP is contributed by the reduced kinetic energy barrier of rate-determining HER step as well as the promotion of the desorption H-2 gas process
Earth‐Abundant Transition‐Metal‐Based Bifunctional Electrocatalysts for Overall Water Splitting in Alkaline Media
No full textⓒ 2020 Wiley?VCH Verlag GmbH & Co. KGaA, Weinheim The depletion of fossil fuels has accelerated the search for clean, sustainable, scalable, and environmentally friendly alternative energy sources. Hydrogen is a potential energy carrier because of its advantageous properties, and the electrolysis of water is considered as an efficient method for its industrial production. However, the high-energy conversion efficiency of electrochemical water splitting requires cost-effective and highly active electrocatalysts. Therefore, researchers have aimed to develop high-performance electrode materials based on non-precious and abundant transition metals for conversion devices. Moreover, to further reduce the cost and complexity in real-world applications, bifunctional catalysts that can be simultaneously active on both the anodic (i.e., oxygen evolution reaction, OER) and cathodic (i.e., hydrogen evolution reaction, HER) sides are economically and technically desirable. This Minireview focuses on the recent progress in transition-metal-based materials as bifunctional electrocatalysts, including several promising strategies to promote electrocatalytic activities for overall water splitting in alkaline media, such as chemical doping, defect (vacancy) engineering, phase engineering, facet engineering, and structure engineering. Finally, the potential for further developments in rational electrode materials design is also discussed11Nsciescopu
Fabrication of tungsten oxide photoanode by doctor blade technique and investigation on its photocatalytic operation mechanism
No full text© 2021 Hydrogen Energy Publications LLCWO3 is a potential material candidate for construction of photoanode for solar driven water splitting. In this work, μm-thick porous WO3 photoanode is prepared by depositing a stable ink made of WO3 nanoparticles and Aristoflex velvet polymer in water using the doctor blade technique, followed by a sintering in air. The nature of WO3 nanoparticles, its loading mass on F-doped tin oxide electrode as well as sintering temperature are examined in order to optimize the photocatalytic activity of the resultant WO3 photoanode. The operation of WO3 photoanode is investigated by varying the light illumination direction and light incident intensity as well as changing the nature of the electrolyte. Dissolved tungsten in electrolyte is quantified by ICP-MS providing insights into the influences of electrolyte nature and operating conditions to the corrosion of WO3. It is proposed that the H2O2 and OH. radical generated as by-products of the photo-driven water oxidation on the photoanode surface are harmful species that accelerate the dissolution of WO3.11Nsciescopu
Porosity-Engineering of MXene as a Support Material for a Highly Efficient Electrocatalyst toward Overall Water Splitting
No full text© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimThe use of 2 D transition metal carbide MXenes as support materials to incorporate catalytically active compounds is of interest because of their unique properties. However, the preparation of well-dispersed catalytic phases on the inter-connected porous MXene network is challenging and has been rarely explored. This work focuses on the synthesis of basal-plane-porous titanium carbide MXene (ac-Ti3C2) that is used subsequently as an effective host for the incorporation of a known catalytically active phase (IrCo) as an effective bifunctional electrocatalyst toward water splitting. The porous ac-Ti3C2 with abundant macro/meso/micropores is prepared by a wet chemical method at room temperature and provides ideal anchor sites for intimate chemical bonding with alien compounds. The resulting IrCo@ac-Ti3C2 electrocatalyst exhibits an excellent reactivity (220 mV at 10 mA cm−2) towards the oxygen evolution reaction in 1.0 m KOH, which surpasses that of the benchmark RuO2, a low voltage cell of 1.57 V (@ 10 mA cm−2) and good long-term durability. Our work demonstrates the effectiveness of porosity engineering in MXene nanosheets as a support material to shorten ion migration pathways, to increase electrolyte accessibility between inter-sheets and to overcome inherited re-stacking and aggregation issues11Nsciescopu
Covalently bonded Ir(IV) on conducted blue TiO2 for efficient electrocatalytic oxygen evolution reaction in acid media
No full text© 2021 by the authors. Licensee MDPI, Basel, Switzerland.The stability of anode electrode has been a primary obstacle for the oxygen evolution reaction (OER) in acid media. We design Ir-oxygen of hydroxyl-rich blue TiO2 through covalent bonds (Ir–O2–2Ti) and investigate the outcome of favored exposure of different amounts of covalent Ir–oxygen linked to the conductive blue TiO2 in the acidic OER. The Ir-oxygen-blue TiO2 nanoclusters show a strong synergy in terms of improved conductivity and tiny amount usage of Ir by using blue TiO2 supporter, and enhanced stability using covalent Ir-oxygen-linking (i.e., Ir oxide) in acid media, leading to high acidic OER performance with a current density of 10 mA cm−2 at an overpotential of 342 mV, which is much higher than that of IrO2 at 438 mV in 0.1 M HClO4 electrolyte. Notably, the Ir–O2–2Ti has a great mass activity of 1.38 A/mgIr at an overpotential 350 mV, which is almost 27 times higher than the mass activity of IrO2 at the same overpotential. Therefore, our work provides some insight into non-costly, highly enhanced, and stable electrocatalysts for the OER in acid media.11Nsciescopu
The impact of government support on firm performance in Vietnam. New evidence from a dynamic approach
Get PDFUsing a sample of private manufacturing small- and medium-sized enterprises (SMEs) in the period 2007–2015, this paper examines the effect of government support on firms’ financial performance in Vietnam. Contrary to many previous studies, the study finds that government assistance affects firms’ financial performance after controlling for heterogeneity, unobservable factors, and dynamic endogeneity. The finding supports the viewpoint of institutional theory. The study also reveals that assistance measures, such as tax exemptions, soft loans, and investment incentives to promote financial performance, are vital for the development of Vietnamese private SMEs
Efficient ammonia synthesis via electroreduction of nitrite using single-atom Ru-doped Cu nanowire arrays
No full text© The Royal Society of Chemistry 2022. Here, we report the highly active and selective electrocatalytic reduction of NO2- ions to value-added NH3 over a single-atom Ru-modified Cu nanowire array on three-dimensional copper foam (Ru-Cu NW/CF) under ambient conditions. The obtained Ru-Cu NW/CF catalyst exhibited a maximum faradaic efficiency of 94.1% and an NH3 yield up to 211.73 mg h(-1) cm(-2) (0.732 mmol h(-1) cm(-2)), which was approximately five times higher than that of the Cu NW/CF catalyst.11Nsciescopu
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