1,721,136 research outputs found
Janus particles: features, synthesis and potential uses, including surface functionalisation
No full textAs the development of nanostructured materials continues to blossom, there is increasing attention to functionalised particles. The so-called Janus particles are anisotropic regions having different physicochemical properties. The recent development of their synthesis in a pH field during suspension as bipolar particles between electrodes has opened the door to improved scalability due to the ease of entraining particles as a slurry in a flowing electrolyte stream. Potential application areas span catalysis of chemical synthesis, sustainable energy conversion and pharmaceutical and biomedical sectors of industry. In view of their versatility, the ability to undergo surface modification and opportunities for facile scale-up, Janus particles might be deployed as building blocks to fabricate functional surfaces having tailored chemical, structural and surface anisotropy. They could prove to be valuable feedstock in 3-D printing and surface finishing of fast prototype components and devices
The use of electrolyte redox potential to monitor the Ce(IV)/Ce(III) couple
Full text linkMathematical modelling of the oxidation reduction redox potential (ORP) of an electrolyte has been carried out for a batch system comprising an electrochemical reactor and an electrolyte circuit containing a redox couple. The ORP can be useful to monitor the environmental impact of chemical species in solution that represent a risk to the environment. Considerations of four fundamental equations, namely, the Nernst equation, a mass balance, Faraday's laws of electrolysis and a first order kinetic equation, leads to an expression for the electrolyte redox potential as a function of the batch time, the electrical charge and the redox concentration. Such an expression facilitates graphical plots which can be used to estimate kinetic parameters, current efficiency and the relative redox concentration. The Ce(IV)/Ce(III) system has been chosen as a model reaction for electrolyte redox potential measurement in a batch recycle system consisting of a pumped flow through a divided FM01-LC parallel plate electrochemical reactor (64 cm2 projected electrode area) and a well mixed tank (3,600 cm3). The differences between experimental and model predictions are discussed
Normal and anomalous electrodeposition of tin–copper alloys from methanesulphonic acid bath containing perfluorinated cationic surfactant
No full textSn–Cu alloys were deposited from a 12?5 vol.-% (1?93 mol dm23) methanesulphonic acid bath containing a perfluorinated, cationic surfactant at 296 K. Electrodeposition was carried out under controlled flow conditions, using rotating disc, rotating cylinder and rotating cylinder Hull cell electrodes. The influences of deposition current and potential, rotation speed, cupric ion concentration, stannous ion level and surfactant concentration on the deposited alloy composition have been investigated. The presence of surfactant resulted in a shift in the Cu deposition potential compared to that of Sn deposition. Both ‘normal’ deposition (Cu deposited at a more positive potential than Sn) and ‘anomalous’ deposition (Sn deposited at a more positive potential than Cu) could be achieved. A series of Sn–Cu alloys was electrodeposited over a wide range of operating conditions to produce matte grey through golden yellow to light brown, surface finishes. Golden yellow coloured bronze deposits, containing 70–80 wt-% Cu and 20–30 wt-%Sn could be obtained. When Sn was deposited preferentially, the Cu content of the alloy was typically in the range 3–9 wt-% along the cathode of the rotating cylinder Hull cell
The continuing development of Magnéli phase titanium sub-oxides and Ebonex® electrodes
No full textMagnéli phase titanium sub-oxides were identified (via x-ray diffraction) in the 1950s as a distinct series of electrically conducting compounds having the general formula TinO2n-1 where 3 < n < 10. Early research on the characterisation of materials based on TinO2n-1 has been well documented. This concise review, which is illustrated by data from the literature and our own laboratory, concerns more recent research on Magnéli phase titanium oxide materials. A brief overview of chemical and physical properties is followed by the applications of electrode materials based on these titanium oxides. Energy conversion technologies (particularly batteries and fuel cells) are shown to be a continued area of research that particularly suits the relatively high electrical conductivity and chemical stability inherent in these materials
The characteristics of a true Tafel slope
No full text2005 is the 100th anniversary of the two original publications of the Tafel equation [1,2]. The international corrosion community is currently celebrating [3] the use of the corresponding Tafel slope (?), which is one of the most frequently used parameters in electrochemical corrosion. Even now, with the use of modern research and testing techniques, both electrochemists and corrosion engineers are frequently encountering this ‘Tafel constant’ in the technical literature and in instrumentation manuals (you can’t use an LPR meter without assuming beta values). Unfortunately, Tafel slopes are commonly misused and measured completely out of context. So, what is a Tafel slope? Perhaps most importantly, when is an apparent ‘Tafel’ slope a true Tafel slope
Modern developments in electrodes for electrochemical technology and the role of surface finishing
No full textFundamental research into electrode materials has focussed on their active area and catalytic ability to drive reaction kinetics. Prerequisites for practical electrodes used in industrial processing and technology include moderate costs, good mechanical, thermal and chemical stability, effective electrocatalysis, a high electrical conductivity and the facility for scale-up, such that an electrochemical engineering approach is important. Following a consideration of important electrode properties, this concise review considers the fabrication, imaging, structure and the dressing of electrode surfaces with particles, coatings and films; nanostructured and hierarchical features are included. Trends in electrodes are noted, using examples from the author’s laboratory. Electrochemical surface finishing techniques make an important contribution to the toolbox of practical techniques capable of industrial development. Approaches to electrode fabrication and surface finishing are considered in application areas such as energy storage and conversion, environmental treatment and tribology.</p
Industrial electrochemistry. 2nd edition
No full textThis book provides a background in electrochemistry and electrochemical engineering and reviews modern applications of electrochemical technology
Electrochemistry: Now and the Future
No full textFew scientists or engineers are aware of the importance of electrochemistry to either their own fields or modern technology. In fact, electrochemistry provides tools that probe problems and enhance understanding of subjects as diverse as medical diagnostics, biology, chemistry, the environment, materials and engineering. It is also the enabling technology behind a range of industries, spanning applications as diverse as chemicals manufacture, effluent treatment and medical monitoring (see Table 1). Although based on the same fundamental principles, the technology associated with these applications can be totally different. For example, the currents passing may vary between 10–9 and 106 amps and involve electrode areas between 10–12 and 104m2
Redox flow batteries for energy storage
No full textThe concept of redox flow batteries (RFBs) is explained and their importance in grid level electrical energy storage is highlighted. The benefits of their modular configuration are linked to a flexible service operation, improved safety, recyclability, moderate costs and reduced environmental impact. Types of RFBs are classified and examples of their electrochemistry are provided, for both commercial devices and promising systems under development. Critical design features of electrodes, unit cells, cell stacks and balance of plant are summarized, together with the role of the power conditioner and the battery management system. Benefits and implications of electrolyte flow are considered and operational parameters affecting cell efficiency, performance and scale-up are given. These include cell resistance, reaction environment, mass transfer, shunt currents and pressure drop as well as cross-over through the membranes. Fundamental electrochemical and techno-economical figures of merit are surveyed. Failure mechanisms and durability are discussed. The scope of validated mathematical modelling and simulation in the design process of efficient RFBs is reviewed. The application of RFBs is illustrated at different scales and competition with other devices is briefly explored. Trends in RFB development and application opportunities are followed by further R&D needs
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