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Topic Review
PEC Reactors for Water/Wastewater Treatment
Now and in the coming years, how we use and treat water, greywater and wastewater will become more important. A suitably designed photoelectrocatalytic (PEC) reactor is one potential solution. The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination of electron–hole pairs and require post-treatment to separate the photocatalyst when a suspension system is used. To reduce recombination and improve the rate of degradation, an externally applied electrical bias can be used where the semiconducting material is immobilised onto an electrically conducive support and connected to a counter electrode. These electrochemically assisted photocatalytic systems have been termed “photoelectrocatalytic” (PEC). The term is stated in the IUPAC Recommendations 2011 as “electrochemically assisted photocatalysis. The role of the photocatalyst is played by a photoelectrode, often a semiconductor”. A short description of photocatalysis is included as it can be beneficial for those unfamiliar with the topic, before moving onto PEC. This entry is adapted from https://doi.org/10.3390/w13091198
  • 1.8K
  • 20 Oct 2021
Topic Review
Hydrogen Economy
Environmental issues make the quest for better and cleaner energy sources a priority. Worldwide, researchers and companies are continuously working on this matter, taking one of two approaches: either finding new energy sources or improving the efficiency of existing ones. Hydrogen is a well-known energy carrier due to its high energy content, but a somewhat elusive one for being a gas with low molecular weight. The so-called "Hydrogen Economy" is based on the use of hydrogen as an energy source. This entry examines the current electrolysis processes for obtaining hydrogen, with an emphasis on alkaline water electrolysis.
  • 1.7K
  • 18 Sep 2021
Topic Review
Electrochemical Immunosensor
Electrochemical immunosensors (EI) are systems that combine the analytical power of electrochemical techniques and the high selectivity and specificity of antibodies in a solid phase immunoassay for a target analyte.
  • 1.7K
  • 02 Dec 2021
Topic Review
Electrochemical Impedance Spectroscopy
Electrochemical impedance spectroscopy is finding increasing use in electrochemical sensors and biosensors, both in their characterisation, including during successive phases of sensor construction, and in application as a quantitative determination technique.
  • 1.7K
  • 28 Apr 2022
Topic Review
OER Electrocatalysts
The oxygen evolution reaction (OER) is the efficiency-determining half-reaction process of high-demand, electricity-driven water splitting due to its sluggish four-electron transfer reaction. Tremendous effects on developing OER catalysts with high activity and strong acid-tolerance at high oxidation potentials have been made for proton-conducting polymer electrolyte membrane water electrolysis (PEMWE), which is one of the most promising future hydrogen-fuel-generating technologies. Electrochemical water splitting involves two heterogeneous multi-step half-reactions, which are referred to as the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). An important frontier in OER electrocatalysis research is the development of the rational design of catalysts. Most of the excellent OER catalysts with high activity and durability are not stable in acidic solutions. They are easily oxidized and decomposed in a strong acid system, which is one of the indispensable working conditions for PEMWE.  Outstanding OER electrocatalysts should have excellent intrinsic activity and sufficient active sites, and these requirements are generally combined with simplicity and controllability.
  • 1.6K
  • 23 Jun 2021
Topic Review
Reconfigurable and Programmable Metamaterials
As an emerging research product in the 21st century, or a new type of artificial composite functional material, metamaterials are subwavelength artificial composite structural materials, whose unit size is generally less than half of the working wavelength.
  • 1.5K
  • 08 Sep 2021
Topic Review
Electrodiffusion in Neuroscience and NPP-Equations
There are two main processes governing the ionic transport, i.e., diffusion—the particle motion caused by a gradient of concentration, and migration—motion of ions caused by a gradient of electrical potential. These two processes are referred to as electrodiffusion. Electrodiffusion of electrolytes serves as a mean for communication in the nervous system. It can directly affect the excitatory transmission in the synaptic cleft. Electrodiffusion maintains the local ions concentration in brain extracellular spaces at heathy levels but may be also involved in the propagation of epileptic seizures during pathological conditions. The accurate interpretation of physiological observations requires better understanding of the underlying electrodiffusion phenomena.The description of electrodiffusion is very often performed using the Nernst–Planck–Poisson (NPP) model. It has been acknowledged that the spatiotemporal dynamics of the ion concentrations in thin dendrites and dendritic spines of nerve cells follow the Nernst–Planck equation, and sub-membrane currents in neuronal membrane have already been successfully described using the NPP model.
  • 1.4K
  • 29 Apr 2021
Topic Review
Ionic Liquids in Electrochemistry
The roles of room temperature ionic liquids (RTILs) and RTIL based solvent systems as proposed alternatives for conventional organic electrolyte solutions are described. Ionic liquids are introduced as well as the relevant properties for their use in electrochemistry (reduction of ohmic losses), such as diffusive molecular motion and ionic conductivity.
  • 1.3K
  • 21 Jan 2021
Topic Review
Lithium-Sulfur Redox Battery
The lithium-sulfur (Li-S) redox battery system is considered to be the most promising next-generation energy storage technology due to its high theoretical specific capacity (1673 mAh/g), high energy density (2600 Wh/kg), low cost, and environmentally friendly nature of sulfur. Though this system is deemed to be the next-generation energy storage device for portable electronics and electric vehicles, its poor cycle life, low coulombic efficiency, and low rate capability limit it from practical applications. These performance barriers were linked to several issues like polysulfide (LiPS) shuttle, inherent low conductivity of charge/discharge end products, and poor redox kinetics. Here, we review the recent developments made to alleviate these problems through an electrocatalysis approach, which is considered to be an effective strategy not only to trap the LiPS but also to accelerate their conversion reactions kinetics. Herein, the influence of different chemical interactions between the LiPS and the catalyst surfaces and their effect on the conversion of liquid LiPS to solid end products are reviewed. Finally, we also discussed the challenges and perspectives for designing cathode architectures to enable high sulfur loading along with the capability to rapidly convert the LiPS.
  • 1.3K
  • 21 Oct 2020
Topic Review
Electrochemical Aptasensors
Over the last few decades, aptamers have attracted a lot of interest in the biosensor industry, because they are the next generation of target receptors that can replace antibody functions. SELEX is an automated procedure and needs only a few days to evolve some binders. This is much shorter compared to antibody selection, which often requires several months. Aptamers can even differentiate the chirality of a molecule and its secondary structure. Aptamers can choose any types of targets with no restrictions. The antibodies undergo permanent degradation, while aptamers can undergo several cycles of denaturation/regeneration. DNA aptamers are acceptable for the design of reusable aptamer detectors, while RNA aptamers can be single-dimensional. The use of aptamers is not limited to specific areas and can be used as recognition molecules in almost any domain. The main limitation is the degradation of RNAs aptamer by ribonuclease. These problems can be solved by modifying RNA aptamers. Another limitation is that the microenvironment will affect the structure of the aptamer and the interactions with the ligand-target. Moreover, the composition of salts has a significant effect on aptamer configuration. The integration of aptamers into detection platforms such as microfluidics and paper-based analytical devices and lab-on-a-chip (LOC) areas for point-of-care (POC) diagnosis is becoming increasingly popular. Aptamer-based detection systems meet most POC diagnostic requirements.
  • 1.2K
  • 28 Sep 2021
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