Electrocatalytic activity of CoFe2O4 thin films prepared by AACVD towards the oxygen evolution reaction in alkaline media

© 2017 The Authors The electrocatalytic behaviour of CoFe 2 O 4 thin films, prepared by aerosol-assisted chemical vapour deposition, towards the oxygen evolution reaction in an alkaline medium is reported. X-ray diffraction and SEM data show that the CoFe 2 O 4 thin films are phase pure and consist of dendrites 0.5–1 μm in diameter rising from the surface with heights ranging from 1 to 3 μm. The CoFe 2 O 4 thin films exhibited an overpotential of 490 mV at a current density of 10 mA cm − 2 , and a Tafel slope of 54.2 mV dec − 1 . Taking into account the electrochemically active surface area, the intrinsic activity of CoFe 2 O 4 was found to be 1.75 mA cm − 2 real at an overpotential of 490 mV. The CoFe 2 O 4 thin films were highly stable and were capable of maintaining catalytic activity for at least 12 h

Observations on the modified Wenker synthesis of aziridines and the development of a biphasic system

A cheap and reliable process for the modified Wenker cyclization to afford aziridines has been achieved using biphasic conditions for a range of amino alcohol starting materials. A 100 mmol “one-pot” process has also been devised and enantiopurity of the starting amino alcohol is retained in the aziridine product

Selective formation of trimethylene carbonate (TMC): atmospheric pressure carbon dioxide utilization

Carbon dioxide utilisation (CDU) is currently gaining increased interest due to the abundance of CO2 and its possible application as a C1 building block. We herein report the first example of atmospheric pressure carbon dioxide incorporation into oxetane to selectively form trimethylene carbonate (TMC), which is a significant challenge as TMC is thermodynamically less favoured than its corresponding co-polymer

Heterogeneous and homogenous catalysts for hydrogen generation by hydrolysis of aqueous sodium borohydride (NaBH4) solutions

It is clear that in order to satisfy global energy demands whilst maintaining sustainable levels of atmospheric greenhouse gases, alternative energy sources are required. Due to its high chemical energy density and the benign by-product of its combustion reactions, hydrogen is one of the most promising of these. However, methods of hydrogen storage such as gas compression or liquefaction are not suitable for portable or automotive applications due to their low hydrogen storage densities. Accordingly, much research activity has been focused on finding higher density hydrogen storage methods. One such method is to generate hydrogen via the hydrolysis of aqueous sodium borohydride (NaBH4) solutions, and this has been heavily studied since the turn of the century due to its high theoretical hydrogen storage capacity (10.8 wt%) and relatively safe operation in comparison to other chemical hydrides. This makes it very attractive for use as a hydrogen generator, in particular for portable applications. Major factors affecting the hydrolysis reaction of aqueous NaBH4 include the performance of the catalyst, reaction temperature, NaBH4 concentration, stabilizer concentration, and the volume of the reaction solution. Catalysts based on noble metals, in particular ruthenium (Ru) and platinum (Pt), have been shown to be particularly efficient at rapid generation of hydrogen from aqueous NaBH4 solutions. However, given the scarcity and expense of such metals, a transition metal-based catalyst would be a desirable alternative, and thus much work has been conducted using cobalt (Co) and nickel (Ni)-based materials to attempt to source a practical option. “Metal free” NaBH4 hydrolysis can also be achieved by the addition of aqueous acids such as hydrochloric acid (HCl) to solid NaBH4. This review summarizes the various catalysts which have been reported in the literature for the hydrolysis of NaBH4

Fabrication and photoelectrochemical studies of BiTiO pyrochlore thin films by aerosol assisted chemical vapour deposition

Phase pure thin film BiTiO photoelectrodes were produced by aerosol assisted chemical vapour deposition at 600 °C for the first time. X-ray diffraction analysis showed that the as-deposited BiTiO films were amorphous in nature; however, post-deposition annealing at 600°C for 12 h significantly increased the crystallinity to give phase pure BiTiO. Scanning electron microscopy revealed that the as-deposited film had a cauliflower-like structure with features ranging from 0.5 to 1.0 μm in size. It was found that the post-annealing step sintered the features together reducing the pores in the structure and giving rise to larger features of 1.0-2.0 μm in size. Optical studies showed that the BiTiO film had a direct band gap of 2.74 eV. The photoelectrochemical properties of BiTiO were tested and it was found that the electrodes exhibited a photocurrent density of 1.8 μA cm at 0.23 V vs. Ag|AgCl. Results showed that BiTiO is an attractive material for photoelectrochemical water splitting

Electrosynthesis of cyclic carbonates from epoxides and atmospheric pressure carbon dioxide

The use of CO2 for the preparation of value-added compounds has dramatically increased due to increased global warming concerns. We herein report an electrochemical cell containing a copper cathode and a magnesium anode that effectively converts epoxides and carbon dioxide to cyclic carbonates under mild electrochemical conditions at atmospheric pressure

Transparent heater based on Al,Ga Co-doped ZnO thin films

Al, Ga co-doped ZnO thin films were deposited on to glass substrates by aerosol assisted chemical transport (AACT) and were studied for application as transparent thin film heaters. The film thickness was around 400 nm after 60 min of AACT deposition; this gave a sheet resistance of 142.5 Ω/sq, which corresponded to a resistivity of 5.7 x 10-3 Ω.cm. The thin films exhibited a maximum transmittance of 90% in the visible region. A mean temperature of 132.3 oC was reached after applying a voltage of 18 V for 10 min, giving a power consumption of 2.11 W. These results could provide a possibility to use Al, Ga co-doped ZnO thin films as transparent heaters to replace the more expensive indium tin oxide

Printed electrodes for flexible, light-weight solid-state supercapacitors - a feasibility study

Purpose – The purpose of this paper is to report on the feasibility of the manufacture of printed rechargeable power sources incorporating, in the first instance, electrode structures from the previous study, and moving on to improved electrode structures fabricated, via flexographic printing, using commercially available inks. It has been shown previously that offset lithography, a common printing technique, can be used to make electrodes for energy storage devices such as primary cells. Design/methodology/approach – A pair of the original Ag/C electrodes, printed via offset lithography, were sandwiched together with a PVA-KOH gel electrolyte and then sealed. The resultant structures were characterised using electrochemical techniques and the performance as supercapacitors assessed. Following these studies, electrode structures of the same dimensions, consisting of two layers, a silver-based current collector covered with a high surface area carbon layer, were printed flexographically, using inks, on a melinex substrate. The characterisation and assessment of these structures, as supercapacitors, was determined. Findings – It was found that the supercapacitors constructed using the offset lithographic electrodes exhibited a capacitance of 0.72 mF/cm2 and had an equivalent series resistance of 3.96 Ω. The structures fabricated via flexography exhibited a capacitance of 4 mF/cm2 and had an equivalent series resistance of 1.25 Ω The supercapacitor structures were subjected to bending and rolling tests to determine device performance under deformation and stress. It was found that supercapacitor performance was not significantly reduced by bending or rolling. Originality/value – This paper provides insight into the use of printed silver/carbon electrodes within supercapacitor structures and compares the performance of devices fabricated using inks for offset lithographic printing presses and those made using commercially available inks for flexographic printing. The potential viability of such structures for low-end and cheap energy storage devices is demonstrated

Ein neues Software-Verfahren zur Optimierung von Schwefelvulkanisationssystemen

Ziel dieser Arbeit war es, einen Softwareansatz zu finden, mit dem sich Schwefelvulkanisationssysteme effizient optimieren lassen. Zu diesem Zweck wurden aus Naturkautschuk (NR) bei Raumtemperatur Compounds mit verschiedenen Anteilen an elementarem Schwefel hergestellt. Aus Zinkoxid wurde durch Beschichtung mit einem organischen Beschleuniger ein Einkomponentenadditiv hergestellt. Dann wurde der Einfluss einer zunehmenden Menge dieses Additivs auf die Vulkanisationseigenschaften der schwefelgefüllten Compounds bei hoher Temperatur bestimmt. Mithilfe eines JavaScript-Programms wurden die Ergebnisse der Vulkanisationsversuche verarbeitet, um eine effiziente Methode zur Optimierung des Schwefelvulkanisationssystems zu entwickeln. Der Nutzer erhält als Ergebnis alle wichtigen Informationen, wie Anvulkanisationszeit, optimale Vulkanisationszeit, Vulkanisationsgeschwindigkeit, Änderung des Vernetzungsgrades, sowie den Bedarf an Vernetzungsadditiven in Abhängigkeit von der Schwefelmenge. Auf diese Weise können zahlreiche Versuche zur Bestimmung der idealen Compoundzusammensetzung für optimale Vulkanisationseigenschaften eingespart werden. The goal of this study was to find a software approach that would make the optimization of the vulcanization system more efficient. For this purpose, a natural rubber (NR) was mixed with different amounts of elemental sulfur at ambient temperature to produce rubber compounds. Zinc oxide was treated with an organic accelerator to produce a convenient single material component to use as additive. The effect of an increasing loading of the surface modified zinc oxide on the cure properties of the sulfur-filled rubber compounds was subsequently measured at a high temperature in a curemeter. Using a JavaScript programme, the cure test results were processed to develop a highly efficient method for optimizing sulfur cure systems for rubber. All the essential information such as scorch and optimum cure times, rate of cure, crosslink density changes in the rubber, and chemical curatives requirement at a given loading of sulfur were subsequently provided for the user. This method removes the need to mix and test the raw rubber with chemical curatives repeatedly to find a compound with ideal cure properties for industrial applications

A novel method for the optimization of sulfur cure systems for rubber using software

The goal of this study was to find a software approach that would make the optimization of the vulcanization system more efficient. For this purpose, a natural rubber (NR) was mixed with different amounts of elemental sulfur at ambient temperature to produce rubber compounds. Zinc oxide was treated with an organic accelerator to produce a convenient single material component to use as additive. The effect of an increasing loading of the surface modified zinc oxide on the cure properties of the sulfur-filled rubber compounds was subsequently measured at a high temperature in a curemeter. Using a JavaScript program, the cure test results were processed to develop a highly efficient method for optimizing sulfur cure systems for rubber. All the essential information such as scorch and optimum cure times, rate of cure, crosslink density changes in the rubber, and chemical curatives requirement at a given loading of sulfur were subsequently provided for the user. This method removes the need to mix and test the raw rubber with chemical curatives repeatedly to find a compound with ideal cure properties for industrial applications