Biz Şekil 4B fotoğraf için ve video, Bayan Jennifer Webb temas açısı ölçümleri tavsiye ve görseller için için optik mikroskop görüntü işleme için Dr. Jonathan Newland teşekkür etmek istiyorum, Şekil 2B&#39;de Bayan Sze-yin Tan çözücü pencere verileri Dr Maxim Joseph Raman spektroskopisi tavsiye ve burada tarif edilen protokoller geliştirmek için yardımcı olan Warwick Elektrokimyada ve Arayüzler Grubu da üyeleri için. Biz de protokol filme kendi bölümü için Max Joseph, Lingcong Meng, Zoe Ayres ve Roy Meyler teşekkür etmek istiyorum.

The authors declare that they have no competing financial interests.

H-sonlandırılmış yüzey özellikle yüksek anodik potansiyellerde 7,40,41 de, elektrokimyasal kararsız olduğu için bir O-sonlandırılmış yüzeyi ile başlayan savunulmaktadır. Yüzey sonlandırma değiştirilmesi gibi (yerel çözelti pH&#39;ı değiştirmek için burada kullanılan) su elektroliz olarak iç küre çiftler, elektron transferi kinetik etkileyebilir. BDD tanecik sınırlarında önemli NDC içeriyorsa Ayrıca, aşırı anodik uygulanması üzerine / katodik potansiyelleri bu zayıf n...

Herhangi bir Elektroanalitik çalışma yaparken elektrot malzemesinin seçimi büyük önem taşımaktadır. Son yıllarda, sp 3 karbon (elmas) malzemeyi işlemek için yeterli bor katkılı &quot;metal benzeri&quot; nedeniyle mükemmel elektrokimyasal (termal ve mekanik) özelliklerine 1,2 ile elektroanalitik geniş bir uygulama yelpazesi için popüler bir seçenek haline gelmiştir 3. Bu yaygın olarak kullanılan diğer elektrot malzemeleri 5-7,3 karşılaştırıldığında korozyona karşı aşırı çözeltisi, sıcaklık ve basınç koşulları 4 ultra geniş bir çözücü camlar, düşük arka plan akımlarında direnci ve düşük birikme sonucu tıkanma, içerir. Ancak, artan sigara elmas karbon (NDC: sp 2), örneğin arka plan akımlar 7,8, farklı iç küre redoks türlerine karşı hem yapısal bütünlük ve duyarlılık değişikliklere giderek artan azalan çözücü pencerede içerik sonuçları. Oksijen 9-12. Öylesine için notBana uygulamaları, NDC varlığı avantajlı 13 olarak görülüyor. Bir malzeme yeterli boron içermiyorsa Ayrıca, bir p-tipi yarı iletken olarak davranırlar ve malzeme en yük taşıyıcıların 7 tüketilir indirgeyici potansiyel penceresinde redoks türleri, azaltılmış hassasiyet gösterir. Son olarak, bor katkılı elmas yüzey kimyası (BDD) ayrıca gözlenen elektrokimyasal yanıt olarak bir rol oynayabilir. Bu, bir hidrojen (H -) - burada yüzey kimyasına ve anılan elmas alt duyarlı olan iç kürenin türler için geçerlidir sona yüzeyi yarı iletken BDD elektrot görünür hale getirebilir &quot;metal-benzeri&quot; 7. BDD üstün özelliklerinden yararlanmak için, malzeme yeterince katkılı genellikle önemlidir ve mümkün olduğunca az rülmesi, içerir. BDD büyümek için kabul yönteme bağlı olarak, özellikleri 14,15 değişebilir. Bu kağıt ilk malzeme ve bir seçecek önerirsonra kullanımdan önce BDD elektrot uygunluğu (yani yeterli bor, minimal NDC) değerlendirilmesi ve için rochemical karakterizasyonu protokol kılavuzu yerel elektrokimyasal protokol doğrulanmış elektrodu kullanılarak pH&#39;ı değiştirerek dayalı bir uygulama açıklanır. Bu süreç uzun bir süre için aşırı uygulanan potansiyeller (ya da akımlar) uygulaması kapsamında korozyon veya dağılması yönünde NDC-free BDD yüzey esneklik yararlanır. Özellikle, BDD elektrotun kullanılması stabil proton (H +) ya da hidroksit oluşturmak için (OH -) 16,17, burada tarif edilen bir ikinci (sensör) çok yakın bir suyun elektrolizi (sırasıyla oksitlenme ya da indirgeme) nedeniyle akıları. Bu şekilde, pH titrasyon deneyleri için, örneğin sistemli bir şekilde sensörün pH ortamı kontrol etmek veya elektrokimyasal süreç en hassas olduğu pH değeri düzeltmek mümkündür. Ikincisi için özellikle yararlıdırSensör kaynağı, örneğin akarsu, göl, deniz ve sistemin pH yerleştirilir uygulamaları ilgi elektrokimyasal ölçümü için optimal değildir. İki son örnekleri şunlardır: elektro ve cıva 17 sıyırma bir pH nötr çözelti içinde lokalize bir düşük pH (i) üretim,; BDD nedeniyle genişletilmiş katodik pencereye 9,18,19 metallerin elektro için tercih edilen bir malzeme olduğunu unutmayın. (ii) yerel olarak nötr kuvvetli alkalin 16&#39;dan pH&#39;ı artırarak yüksek pH mevcut hidrojen sülfür, bir elektrokimyasal saptanabilir formunun miktarının belirlenmesi.

<table><tbody><tr><td>Pt Wire</td><td></td><td></td><td>Counter Electrode</td></tr><tr><td>Saturated Calomel Electrode</td><td>IJ Cambria Scientific Ltd.</td><td>2056</td><td>Reference Electrode (alternatively use Ag|AgCl)</td></tr><tr><td>BDD Electrode</td><td></td><td></td><td>Working Electrode</td></tr><tr><td>Iridium Tetrachloride</td><td>VWR International Ltd</td><td>12184.01</td><td></td></tr><tr><td>Hydrogen Peroxide</td><td>Sigma-Aldrich</td><td>H1009</td><td>(30% w/w) Corrosive</td></tr><tr><td>Oxalic Acid&amp;nbsp;</td><td>Sigma-Aldrich</td><td>241172</td><td>Harmful, Irritant</td></tr><tr><td>Anhydrous Potassium Chloride</td><td>Sigma-Aldrich</td><td>451029</td><td></td></tr><tr><td>Sulphuric Acid</td><td>VWR International Ltd</td><td>102765G</td><td>(98%) Corrosive</td></tr><tr><td>Potassium Nitrate</td><td>Sigma-Aldrich</td><td>221295</td><td></td></tr><tr><td>Hexaamine Ruthenium Chloride</td><td>Strem Chemicals Inc.</td><td>44-0620</td><td>Irritant</td></tr><tr><td>Perchloric Acid</td><td>Sigma-Aldrich</td><td>311421</td><td>Oxidising, Corrosive</td></tr><tr><td>2-Propanol</td><td>Sigma-Aldrich</td><td>24137</td><td>Flammable</td></tr><tr><td>Nitric Acid</td><td>Sigma-Aldrich</td><td>695033</td><td>Oxidising, Corrosive</td></tr><tr><td>Sputter/ Evapourator</td><td></td><td></td><td>With Ti &amp;amp; Au targets</td></tr><tr><td>Raman</td><td></td><td></td><td>514.5 nm laser</td></tr><tr><td>Annealing Oven</td><td></td><td></td><td>Capable of 400 &amp;deg;C</td></tr><tr><td>Ag paste</td><td>Sigma-Aldrich</td><td>735825</td><td>or other conductive paint</td></tr><tr><td>Potentiostat</td><td></td><td></td><td></td></tr><tr><td>pH Buffer solutions</td><td>Sigma-Aldrich</td><td>38740-38752</td><td>Fixanal buffer concentrates</td></tr><tr><td>Phenolphthalein Indicator</td><td>VWR International Ltd</td><td>210893Q</td><td></td></tr><tr><td>Methyl Red Indicator</td><td>Sigma-Aldrich</td><td>32654</td><td></td></tr></tbody></table>

assessment of boron doped diamond electrode quality and application to in situ modification of local ph by water electrolysis

Bor kaplı elmas (BDD), elektrotlar vb uzatılmış çözücü pencere, düşük arka plan akımları, korozyon direnci, olarak belirtilen özelliklerinden çoğunun yüzey katalitik olarak atıl doğasından kaynaklanan bir elektrot malzemesi olarak önemli ölçüde söz göstermiştir. Büyüme süreci sırasında olmayan bir elmas-karbon (NDC), elektrot matris içine dahil edilmekte, eğer yüzey daha fazla katalitik olarak aktif hale gelir, ancak, elektrokimyasal özellikleri değişir. Bu nedenle bu electrochemist kalitesi haberdar ve kullanımdan önce BDD elektrotun önemli elektrokimyasal özelliklerinin elde edilen olması önemlidir. Bu yazıda BDD elektrot önemsiz NDC yani önemsiz sp 2 karbon içerip içermediğini anlamak için, Raman mikroskobu, kapasite, çözücü pencere ve redoks elektrokimya dahil karakterizasyon adımlar, bir dizi anlatılmaktadır. Bir uygulama katalitik atıl yararlanır hangi vurgulanırve NDC-serbest yüzey korozyona dayanıklı yapısı nedeniyle BDD elektrodun su elektroliz kararlı ve ölçülebilir yerel proton ve hidroksit üretimi yani. Iridyum oksit kaplı BDD elektrodlar kullanılarak, su elektroliz bağlı lokal pH değişikliği ölçmek için bir yaklaşım, detaylı bir şekilde tarif edilmektedir.

Raman ve elektrokimyasal özellikleri farklı takviye yoğunlukları ile temsili BDD macrodisc elektrotlar elde edilmiştir ve NDC önemli ve önemsiz düzeyleri, hem 1 ve 2 Şekil. Şekil 1A ve B gösterisi tipik Raman verileri ince film mikrokristalin BDD ve daha büyük tahıl NDC içeren için bağlantısız BDD, sırasıyla, metalik eşiğinin üzerinde katkılı. NDC varlığı 1400 ve 1600 cm -1 arasın...

Watch this Scientific Journal Video about Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis at JoVE.com

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

Bir protokol in situ pH üretimi deneylerinde bir bor kaplı elmas (BDD), elektrot ve bir sonraki uygulamaya önemli elektrokimyasal parametrelerin tanımlanması için tarif edilmektedir.

Bor Katkılı Elmas Elektrot Kalite ve Uygulamaya değerlendirilmesi<em&gt; In Situ</em&gt; Su Elektroliz ile Yerel pH Modifikasyonu

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended ...

assessment-boron-doped-diamond-electrode-quality-application-to-situ

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

14.7K Görüntüleme.  University of Warwick.  Bir protokol in situ pH üretimi deneylerinde bir bor kaplı elmas (BDD), elektrot ve bir sonraki uygulamaya önemli elektrokimyasal parametrelerin tanımlanması için tarif edilmektedir. 

Video: Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

Electrochemically and Bioelectrochemically Induced Ammonium Recovery

Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ammonium from an ammonium-rich stream is demonstrated using an electrochemical and a bioelectrochemical system. Both systems are controlled by a potentiostat to either fix the current (for the electrochemical cell) or fix the potential of the working electrode (for the bioelectrochemical cell). In the bioelectrochemical cell, electroactive bacteria catalyze the anodic reaction, whereas in the electrochemical cell the potentiostat applies a higher voltage to produce a current. The current and consequent restoration of the charge balance across the cell allow the transport of cations, such as ammonium, across a cation exchange membrane from the anolyte to the catholyte. The high pH of the catholyte leads to formation of ammonia, which can be stripped from the medium and captured in an acid solution, thus enabling the recovery of a valuable nutrient. The flux of ammonium across the membrane is characterized at different anolyte ammonium concentrations and currents for both the abiotic and biotic reactor systems. Both systems are compared based on current and removal efficiencies for ammonium, as well as the energy input required to drive ammonium transfer across the cation exchange membrane. Finally, a comparative analysis considering key aspects such as reliability, electrode cost, and rate is made.
This video article and protocol provide the necessary information to conduct electrochemical and bioelectrochemical ammonia recovery experiments. The reactor setup for the two cases is explained, as well as the reactor operation. We elaborate on data analysis for both reactor types and on the advantages and disadvantages of bioelectrochemical and electrochemical systems.

We demonstrate the extraction of ammonium from an ammonium-rich stream using an electrochemical and a bioelectrochemical system. The reactor setup, operation and data analysis are discussed.

Elektrokimyasal ve Bioelectrochemically Kaynaklı Amonyum Kurtarma

Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ...

Kimya

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (&#181;PAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

The study demonstrates the growth of iridium oxide-reduced graphene oxide (IrO2-RGO) nanohybrid thin films on irregular and rough screen-printed carbon substrate through a green electrochemical synthesis, and their implementation as a pH sensor with a patterned paper-fluidic platform.

Tek Elektrokimyasal Kağıt mikroakışkan pH Sensörler olarak iridyum Oksit azaltılmış Grafen Oksit nanohibrit İnce Film Modifiye Ekran baskılı Elektrotlar

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use ...

Mühendislik

Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1

Direct electrochemical detection of c-type cytochrome complexes embedded in the bacterial outer membrane (outer membrane c-type cytochrome complexes; OM c-Cyts) has recently emerged as a novel whole-cell analytical method to characterize the bacterial electron transport from the respiratory chain to the cell exterior, referred to as the extracellular electron transport (EET). While the pathway and kinetics of the electron flow during the EET reaction have been investigated, a whole-cell electrochemical method to examine the impact of cation transport associated with EET has not yet been established. In the present study, an example of a biochemical technique to examine the deuterium kinetic isotope effect (KIE) on EET through OM c-Cyts using a model microbe, Shewanella oneidensis MR-1, is described. The KIE on the EET process can be obtained if the EET through OM c-Cyts acts as the rate-limiting step in the microbial current production. To that end, before the addition of D2O, the supernatant solution was replaced with fresh media containing a sufficient amount of the electron donor to support the rate of upstream metabolic reactions, and to remove the planktonic cells from a uniform monolayer biofilm on the working electrode. Alternative methods to confirm the rate-limiting step in microbial current production as EET through OM c-Cyts are also described. Our technique of a whole-cell electrochemical assay for investigating proton transport kinetics can be applied to other electroactive microbial strains.

Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1

Here we present a protocol of whole-cell electrochemical experiments to study the contribution of proton transport to the rate of extracellular electron transport via the outer-membrane cytochromes complex in Shewanella oneidensis MR-1.

Elektrokimyasal algılama döteryum Kinetik izotop etkisi üzerinde ekstraselüler elektron taşıma Shewanella Corynebacterium Bay-1

Direct electrochemical detection of c-type cytochrome complexes embedded in the bacterial outer membrane (outer membrane c-type cytochrome complexes; OM ...

Biyokimya

Self-standing Electrochemical Set-up to Enrich Anode-respiring Bacteria On-site

Anaerobic respiration coupled with electron transport to insoluble minerals (referred to as extracellular electron transport [EET]) is thought to be critical for microbial energy production and persistence in many subsurface environments, especially those lacking soluble terminal electron acceptors. While EET-capable microbes have been successfully isolated from various environments, the diversity of bacteria capable of EET is still poorly understood, especially in difficult-to-sample, low energy or extreme environments, such as many subsurface ecosystems. Here, we describe an on-site electrochemical system to enrich EET-capable bacteria using an anode as a respiratory terminal electron acceptor. This anode is connected&#160;to a cathode capable of&#160;catalyzing abiotic oxygen reduction. Comparing this approach with electrocultivation methods that use a potentiostat for poising the electrode potential, the two-electrode system does not require an external power source. We present an example of our on-site enrichment utilized in an alkaline pond at the Cedars, a terrestrial serpentinization site in Northern California. Prior attempts to cultivate mineral reducing bacteria were unsuccessful, which is likely due to the low-biomass nature of this site and/or the low relative abundance of metal reducing microbes. Prior to implementing our two-electrode enrichment, we measured the vertical profile of dissolved oxygen concentration. This allowed us to place the carbon felt anode and platinum-electroplated carbon felt cathode at depths that would support anaerobic and aerobic processes, respectively. Following on-site incubation, we further enriched the anodic electrode in the laboratory and confirmed&#160;a distinct microbial community compared to the surface-attached or biofilm communities normally observed at the Cedars. This enrichment subsequently led to the isolation of the first electrogenic microbe from the Cedars. This method of on-site microbial enrichment has the potential to greatly enhance the isolation of EET-capable bacteria from low biomass or difficult to sample habitats.

On-site microbial enrichment or in situ cultivation techniques can facilitate the isolation of difficult-to-culture microbial taxa, especially from low-biomass or geochemically extreme environments. Here, we describe an electrochemical set-up without using an external power source to enrich microbial strains that are capable of extracellular electron transport (EET).

Anot respiring bakteri yerinde zenginleştirmek için kendini ayakta elektrokimyasal Set-up

Anaerobic respiration coupled with electron transport to insoluble minerals (referred to as extracellular electron transport [EET]) is thought to be ...

Çevre

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

LiPON tabanlı katı hal lityum-iyon Nanobatteries in Situ test etmek için odaklı iyon kiriş imalatı

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate multiple processes responsible for long-term performance decay. Given the complexity of physical processes occurring inside the cell, it is often challenging to achieve a full understanding of the root causes of this performance degradation. This difficulty arises in part from the fact that any electrochemical measurement of a battery will return the combined contributions of all components in the cell. Incorporation of a reference electrode can solve part of the problem, as it allows the electrochemical reactions of the cathode and the anode to be individually probed. A variation in the voltage range experienced by the cathode, for example, can indicate alterations in the pool of cyclable lithium ions in the full-cell. The structural evolution of the many interphases existing in the battery can also be monitored, by measuring the contributions of each electrode to the overall cell impedance. Such wealth of information amplifies the reach of diagnostic analysis in Li-ion batteries and provides valuable input to the optimization of individual cell components. In this work, we introduce the design of a test cell able to accommodate multiple reference electrodes, and present reference electrodes that are appropriate for each specific type of measurement, detailing the assembly process in order to maximize the accuracy of the experimental results.

The incorporation of reference electrodes in a Li-ion battery provides valuable information to elucidate degradation mechanisms at high voltages. In this article, we present a cell design that accommodates multiple reference electrodes, along with the assembly steps to assure maximum accuracy of the data obtained in electrochemical measurements.

İn Situ Lithiated referans elektrot: Dört elektrot tasarım operando empedans spektroskopisi için

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate ...

Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries of the metal. Using this method, a crack free, thin-film macroelectrode surface with up to 40 times increase in active surface area was obtained. The roughening is easy to do in a standard electrochemical characterization laboratory and incudes the application of voltage pulses followed by extended application of a reductive voltage in a perchloric acid solution. The protocol includes the chemical and electrochemical preparation of both a macroscale (1.2 mm diameter) and microscale (20 &#181;m diameter) platinum disc electrode surface, roughening the electrode surface and characterizing the effects of surface roughening on electrode active surface area. This electrochemical characterization includes cyclic voltammetry and impedance spectroscopy and is demonstrated for both the macroelectrodes and the microelectrodes. Roughening increases electrode active surface area, decreases electrode impedance, increases platinum charge injection limits to those of titanium nitride electrodes of same geometry and improves substrates for adhesion of electrochemically deposited films.

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries. The electrochemical techniques of cyclic voltammetry and impedance spectroscopy are demonstrated to characterize these electrode surfaces.

Ince-Film platin makro ve Mikroelektrotlar elektrokimyasal kaba doldurma

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries ...

Electrochemical Preparation of Poly(3,4-Ethylenedioxythiophene) Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of 3,4-ethylenedioxythiophene (EDOT) monomer in an aqueous and an organic solution. Cyclic voltammetry (CV) was used in the synthesis of PEDOT thin layers. Lithium perchlorate (LiClO4) was used as a dopant in both aqueous (aqueous/acetonitrile (ACN)) and organic (propylene carbonate (PC)) solvent systems. After the PEDOT layer was created in the organic system, the electrode surface was acclimatized by successive cycling in an aqueous solution for use as a sensor for aqueous samples. 
The use of an aqueous-based electropolymerization method has the potential benefit of removing the acclimatization step to have a shorter sensor preparation time. Although the aqueous method is more economical and environmentally friendly than the organic solvent method, superior PEDOT formation is obtained in the organic solution. The resulting PEDOT electrode surfaces were characterized by scanning electron microscopy (SEM), which showed the constant growth of PEDOT during electropolymerization from the organic PC solution, with rapid fractal-type growth on gold (Au) microelectrodes.

Electrochemical Preparation of Poly3,4-Ethylenedioxythiophene Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

We describe aqueous and organic solvent systems for the electropolymerization of poly(3,4-ethylenedioxythiophene) to create thin layers on the surface of gold microelectrodes, which are used for sensing low molecular weight analytes.

Ürik Asit Algılama Uygulamaları için Altın Mikroelektrotlar Üzerine Poli(3,4-Etilendioksitiofen) Tabakalarının Elektrokimyasal Hazırlanması

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of ...

Manufacturing of a Nafion-coated, Reduced Graphene Oxide/Polyaniline Chemiresistive Sensor to Monitor pH in Real-time During Microbial Fermentation

Here, we report the engineering of a solid-state micro pH sensor based on polyaniline-functionalized, electrochemically reduced graphene oxide (ERGO-PA). Electrochemically reduced graphene oxide acts as the conducting layer and polyaniline acts as a pH-sensitive layer. The pH-dependent conductivity of polyaniline occurs by doping of holes during protonation and by the dedoping of holes during deprotonation. We found that an ERGO-PA solid-state electrode was not functional as such in fermentation processes. The electrochemically active species that the bacteria produce during the fermentation process interfere with the electrode response. We successfully applied Nafion as a proton-conducting layer over ERGO-PA. The Nafion-coated electrodes (ERGO-PA-NA) show a good sensitivity of 1.71 &#937;/pH (pH 4 - 9) for chemiresistive sensor measurements. We tested the ERGO-PA-NA electrode in real-time in the fermentation of Lactococcus lactis. During the growth of L. lactis, the pH of the medium changed from pH 7.2 to pH 4.8 and the resistance of the ERGO-PA-NA solid-state electrode changed from 294.5 &#937; to 288.6 &#937; (5.9 &#937; per 2.4 pH unit). The pH response of the ERGO-PA-NA electrode compared with the response of a conventional glass-based pH electrode shows that reference-less solid-state microsensor arrays operate successfully in a microbiological fermentation.

Here, we report the protocol for the fabrication of a Nafion-coated, polyaniline-functionalized, electrochemically reduced graphene oxide chemiresistive micro pH sensor. This chemiresistor-based, solid-state micro pH sensor can detect pH changes in real-time during a Lactococcus lactis fermentation process.

Nafion kaplı imalatı, mikrobiyal fermantasyon sırasında gerçek zamanlı monitör pH grafen oksit/Polyaniline Chemiresistive sensör azaltılmış

Here, we report the engineering of a solid-state micro pH sensor based on polyaniline-functionalized, electrochemically reduced graphene oxide (ERGO-PA). ...

Biyomühendislik

Electrochemical Measurements of Supported Catalysts Using a Potentiostat/Galvanostat

Source: Laboratory of Dr. Yuriy Rom&#225;n &#8212; Massachusetts Institute of Technology
A potentiostat/galvanostat (often referred to as simply a potentiostat) is an instrument that measures current at an applied potential (potentiostatic operation) or measures potential at an applied current (galvanostatic operation) (Figure 1). It is the most commonly used instrument in the electrochemical characterization of anode and cathode materials for fuel cells, electrolyzers, batteries, and supercapacitors.
Conventionally, these anode and cathode materials are interfaced with a potentiostat via a three-electrode electrochemical cell. The electrode leads from the potentiostat are connected to the reference electrode, the counter electrode (often called the auxiliary electrode), and the working electrode (which contains the test material of interest). The electrochemical cell is then filled with a high ionic strength electrolyte solution, such as an acidic, alkaline, or salt solution. The media for this high ionic strength solution is typically aqueous; however, for applications necessitating higher operating cell potential windows, such as batteries and supercapacitors, non-aqueous media is often used. The cell media is degassed with an inert gas (to prevent unwanted side reactions) or with a test gas (if the test reaction involves a gas at one of the electrodes).
Alternatively, a salt bridge or membrane is employed to maintain ionic contact if the two half cells are to be measured in different electrolytes. In heterogeneous electrocatalysis, this type of &#34;two compartment&#34; cell is often used if the test molecule at the working electrode is also reactive at the counterelectrode. This happens frequently as the counterelectrode typically employed is platinum, which is a highly active catalyst for many reactions. Here, single compartment cells will be used, where all three electrodes are in the same media.
This video will explain the process of polishing a working electrode, preparing a catalyst ink, mounting the catalyst ink onto the working electrode, preparing the electrochemical cell, and then performing electrochemical measurements. The measurements that are performed include: cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronopotentiometry (CP), and chronoamperometry (CA).
<img alt="Figure 1" src="/files/ftp_upload/5698/5698fig1.jpg" /> 
Figure 1. An example of a single compartment electrochemical cell. a.) Teflon cap, b.) glass cell, c.) Pt wire counter electrode, d.) working electrode, e.) Ag/AgCl reference electrode, f.) 0.5 M aqueous sulfuric acid electrolyte solution.

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