Surface Properties Of Electrodes Research Articles

Optimization of the Zinc Deposition Interface by Sn Nanoparticles for Fast-Charging Zinc Metal Anodes.

The electrodeposition behavior of zinc metal anodes critically correlates with the electrode surface properties. The tendency for inhomogeneous deposition of zinc is more severe, especially under high current density. Herein, the surface structure of zinc and zinc deposition substrates is reconstructed with a uniform metal tin (Sn) coating via a simple evaporation method. Sn nanoparticles can serve on metal nuclei to reduce the Zn nucleation barrier and enable more nucleation sites for even deposition. Moreover, the mechanical stability of the electrode surface is improved via Zn-Sn alloying. Consequently, the uniform Zn deposition/dissolution behavior on Sn-modified two- and three-dimensional copper substrates is reflected in the stable Coulombic efficiency and reduced polarization. The Sn@Zn electrode is endowed with superior stability at a high current density (800 h at 20 mA cm-2). More encouragingly, the full cell installed with a carbon nanotube/MnO2 cathode maintains enduring stability (700 cycles) at 1 A g-1. This work enlightens metal alloy as an effective and instructive modification strategy toward stabilized zinc anodes.

An electrochemical immunosensor based on AgNPs/Nafion-GCE for detection of salivary lactoferrin: Alzheimer’s disease biomarker

This study describes the development of a label-free electrochemical immunosensor using AgNPs/Nafion–modified glassy carbon electrode (GCE) for the detection of lactoferrin (Lf), a crucial biomarker for various diseases. Salivary Lf could be presented as a new biomarker candidate for Alzheimer’s disease (AD), serving as a non-invasive and cost-effective predictor of amyloid pathology. The construction of the label-free immunosensor was characterized through scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealing significant changes in electron transfer rates during each step of the assembly process. The electrochemical signal of the immunosensor fabrication was measured at each step and the resulting electrode surface properties were significantly enhanced by the AgNPs/Nafion deposition. The immunosensor demonstrated a linear dynamic range of 0.005–100 μg/mL based on DPV, with a LOD of 0.025 μg/mL. It exhibited good reproducibility and selectivity towards potential interfering substances. Testing with Lf spiked human saliva samples resulted in recovery rates between 101 % and 103 %. This AgNPs/Nafion-based immunosensor provides a promising platform for the rapid and sensitive detection of Lf in AD assessment.

Exploring Platinum Thin Films as Electrodes for High‐Temperature and ‐Pressure Electrochemical Studies in Aqueous Systems

ABSTRACTThis work reports a methodology for the fabrication of Pt thin‐film electrodes for electrochemical studies in hydrothermal systems. The research process was meticulous, with particular attention paid to the multilayer Ti/Pt/Ti/Al2O3 film structure and annealing conditions that are expected to impact the morphology of the films, surface composition and electrochemical response. The findings of this study are significant, as they provide valuable insights into the behaviour of Pt thin‐film electrodes in various media and conditions. Two different approaches were adopted for the preparation of the electrodes: in one case, the Ti/Pt/Ti/Al2O3 films deposited on sapphire wafers were exposed to rapid thermal annealing at 900°C under argon for 5 min, followed by argon ion milling to etch the final electrode pattern (Pt‐RA(900)), while in the other case, uncapped Pt films were annealed, after etching, in a tubular oven under argon at specific temperatures between 200°C and 900°C (Pt‐TO). Rapid annealing at 900°C on capped films resulted in the formation of a Pt3Ti intermetallic alloy with remarkable mechanical and chemical stability even after 10 h of immersion in deionised water, acid (0.1 M H2SO4) and alkaline media (0.1 M KOH) conditions at temperatures up to 150°C, despite the dissolution of the Al2O3 top layer at 150°C and long immersion times (> 10 h). In the case of uncapped Pt films, diffusion and oxidation of Ti through the Pt film at high temperature resulted in the formation of TiO2 on the surface of Pt. The results were confirmed by using a comprehensive suite of ex‐situ characterisation techniques to follow changes in the Pt electrode surface morphology and composition before and after immersion in H2O, 0.1 M H2SO4 and 0.1 M KOH solutions under argon. Ex‐situ electrochemical characterisation studies were also conducted to correlate the changes in the electrode surface properties, including the electrochemical surface area, with different annealing conditions and after various hydrothermal treatments in neutral, alkaline and acidic media.

High‐performance Porous Electrodes for Flow Batteries: Improvements of Specific Surface Areas and Reaction Kinetics

AbstractElectrodes, which offer sites for mass transfer and redox reactions, play a crucial role in determining the energy efficiencies and power densities of redox flow batteries. This review focuses on various approaches to enhancing electrode performance, particularly the methods of surface etching and catalyst deposition, as well as some other advanced strategies for regulating electrode surface properties. These approaches aim to increase active sites and enhance kinetics for the redox reactions, which are crucial for elevating power density and electrolyte utilization, eventually determining the performance of the flow battery. Highlighting the need for interdisciplinary research, this mini‐review suggests that future advancements in electrode design will significantly impact the commercial viability and adoption of redox flow batteries in sustainable energy storage solutions.

Modulating Surface Cation Concentration via Tuning the Molecular Structures of Ethylene Glycol-Functionalized PEDOT for Improved Alkaline Hydrogen Evolution Reaction.

The sluggish catalytic kinetics of nonprecious metal-based electrocatalysts often hinder them from achieving efficient hydrogen evolution reactions (HERs). Poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have been promising materials for various electrochemical applications. Nevertheless, previous studies have demonstrated that PEDOT coatings can be detrimental to HER performance. In this study, we investigated the alkaline HER efficiency of nickel foam coated with three types of ethylene glycol (EG)-functionalized EDOT. Specifically, EDOT derivatives bearing hydroxyl (-OH) and methoxy (-OCH3) end groups on the EG side chain and molecules containing two EDOT units are interconnected via EG moieties. EG groups are selected due to their strong interaction with alkali metal cations. Intriguingly, improved HER performance is observed on all electrodes coated with EG-functionalized EDOTs. Electrochemical impedance spectroscopy, electrochemical quartz crystal microbalance with dissipation, and XPS analysis are employed to explore the origin of enhanced HER efficiency. The results suggest the EG moieties can induce locally concentrated ions near the electrode surface and facilitate water dissociation through noncovalent interactions. The influence of EG chain length is systematically investigated by synthesizing molecules with di-EG, tetra-EG, and hexa-EG functionalities. This study highlights the importance of molecular design in modifying electrode surface properties to promote alkaline HER.

Towards Low Cost and Long Duration Iron-Air Flow Batteries

The electrification of the energy economy necessitates the development of low cost and large scale energy storage technologies that can integrate intermittent renewables (e.g. solar and wind). Among the various technological options (e.g. lithium ion batteries, vanadium redox flow batteries), metal-air batteries are promising alternatives owing to their high energy density, safety, and use of abundant raw materials. Moreover, when combined with the principles of redox flow batteries, mass transfer is enhanced, which results in a more uniform metal deposition and a reduction in the metal electrode passivation [2]. Furthermore, metal-air flow batteries could enable decoupling of power and energy, while retaining the scalability advantages of redox flow batteries. Additionally, they are more compact than conventional redox flow batteries since only one electrolyte tank is needed.Several metal-air flow battery systems have been investigated such as vanadium-air [3], lithium-air [4] and zinc-air batteries [5]. However, they suffer from limitations which challenge their scalability. Specifically, vanadium is costly and only available in certain regions, lithium requires the use of organic solvents which compromises the battery safety, and zinc forms dendrites leading to a lower performance and safety issues. In this context, iron-based batteries are a promising alternative due to their high specific capacity, low cost, large availability, safety, non-toxicity, and recyclability. Compared to zinc, iron is also less prone to dendrite formation during cycling in aqueous electrolytes since iron deposition kinetics is slower[6]. Despite these advantages, the performance of the iron anode is limited by electrode degradation during cycling due to phase transformations, hydrogen evolution, and low utilization of the activate material [6], which motivates fundamental research to advance the performance and durability of the system.In this poster presentation, we will discuss the main goals of our new project FAIR-RFB [7]. Our overall aim is to develop a low cost and durable iron-air flow battery system and, to this goal, we will investigate, (i) the role of porous electrode microstructure in defining the performance of iron-air flow batteries, (ii) the influence of electrode surface properties in determining transport phenomena, kinetics, selectivity and durability, and (iii) new electrochemical reactor architectures for high power iron-air redox flow batteries.

Tuning the Chemical and Electrochemical Properties of Paper-Based Carbon Electrodes by Pyrolysis of Polydopamine.

Electrochemical paper-based analytical devices represent an important platform for portable, low-cost, affordable, and decentralized diagnostics. For this kind of application, chemical functionalization plays a pivotal role to ensure high clinical performance by tuning surface properties and the area of electrodes. However, controlling different surface properties of electrodes by using a single functionalization route is still challenging. In this work, we attempted to tune the wettability, chemical composition, and electroactive area of carbon-paper-based devices by thermally treating polydopamine (PDA) at different temperatures. PDA films were deposited onto pyrolyzed paper (PP) electrodes and thermally treated in the range of 300-1000 °C. After deposition of PDA, the surface is rich in nitrogen and oxygen, it is superhydrophilic, and it has a high electroactive area. As the temperature increases, the surface becomes hydrophobic, and the electroactive area decreases. The surface modifications were followed by Raman, X-ray photoelectron microscopy (XPS), laser scanning confocal microscopy (LSCM), contact angle, scanning electron microscopy (SEM-EDS), electrical measurements, transmission electron microscopy (TEM), and electrochemical experiments. In addition, the chemical composition of nitrogen species can be tuned on the surface. As a proof of concept, we employed PDA-treated surfaces to anchor [AuCl4]- ions. After electrochemical reduction, we observed that it is possible to control the size of the nanoparticles on the surface. Our route opens a new avenue to add versatility to electrochemical interfaces in the field of paper-based electrochemical biosensors.

Unraveling the Fundamental Concepts of Superaerophobic/Superhydrophilic Electrocatalysts for Highly Efficient Water Electrolysis: Implications for Future Research

AbstractElectrochemical water splitting is a highly effective method for carbon‐free hydrogen production. While significant efforts have been made to develop efficient and cost‐effective electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), the optimization of electrode surface properties has been largely overlooked. Inadequate mass diffusion, especially at high bath voltage, hampers the energy transfer efficiency of water electrolysis. To overcome these challenges, precise design of superaerophobic/superhydrophilic electrodes can effectively separate gas bubbles from the catalyst surface and enhance mass transfer, improving overpotential and Faraday efficiency. This article underscores the importance of designing electrocatalysts with well‐designed surface properties to address these challenges. It also discusses characterization techniques for evaluating surface properties and provides examples of applications for superaerophobic/superhydrophilic electrodes in energy storage and conversion systems, electrochemical biosensors, and industrial processes, etc. Overall, optimizing the surface properties of electrocatalysts holds promise for enhancing the efficiency of gas‐involving reactions and energy conversion systems.

Microbial-Inspired Surface Patterning for Selective Bacterial Actions for Enhanced Performance in Microbial Fuel Cells.

The performance of any bio-electrochemical system is dependent on the efficiency of electrode-microbial interactions. Surface properties play a focal role in bacterial attachment and biofilm formation on the electrodes. In addition to electrode surface properties, selective bacterial adhesion onto the electrode surface is mandatory to mitigate energy loss due to undesired bacterial interactions on the electrode surface. In the present study, microbial-patterned graphite scaffolds are developed for selective bacterial-electrode interactions. A power density as high as 1105 mW/m2 is achieved with mG-E (a graphite electrode patterned with Escherichia coli), which is about 3 times higher than that of the pristine graphite electrode (370 mW/m2). Initial mechanical pre-treatment of the graphite electrode, followed by bacterial patterning, results in the formation of a unique cobblestone topography with a tuned surface area of 127.12 m2/g. This provides suitable morphology with enhanced active sites for selective bacterial intercalation in graphite layers. This cannot be otherwise achieved by any mechanical or other means. A unique methodology of symbolic regression is adopted to validate a genetic algorithm suitable for predicting a perfect correlation between surface characteristics and electrochemical characteristics with a minimum root-mean-square error of 0.08. The bacterial intercalation onto the graphite electrode causes protuberance of the graphite layers that reduces the surface potential and resistance, leading to high electron transfer. The study presents a unique bacterial-inspired surface patterning on the anode, which is critical for the performance of a microbial fuel cell.

Label-free electrochemical immunosensor for picomolar detection of the cervical cancer biomarker MCM5

An immunosensor for label-free electrochemical detection of MiniChromosome Maintenance Protein 5, MCM5, a protein overexpressed in cervical cancer, based on a gold electrode is reported. The electrode was first modified with a submonolayer (capture layer) of 11-mercaptoundecanoic acid (11-MUA) and then activated with N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to immobilize the capture antibody. The change in electrode surface properties (wettability) during the formation of the 11-MUA layers was determined using the static water contact angle (WCA). The binding of MCM5 antigens to the capture antibody was monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using 5 mM [Fe(CN)6]3−/4− in 0.1 M LiClO4(aq) as an electroactive probe. AC Impedance was used to measure charge transfer resistance (Rct), which reflects impeded electron transfer when the antigen is bound to the antibody functionalized surface. After exposing the antibody-functionalized surface to MCM5 antigens, Rct increases linearly with the logarithmic value of MCM5 antigen concentration, with a linear dynamic range of 10−6 to 10−11 g/mL, a correlation coefficient of 0.99, and a detection limit of 2.9 pM (10−11 g/mL). This excellent sensitivity was achieved with simple preparation steps and minimal reagent consumption, without the need for complicated procedures such as enzymatic amplification, fluorescent labeling, or nanoparticle modification.

Gold nanoparticles/over-oxidized poly-eriochrome black T film modified electrode for determination of arsenic.

A glassy carbon electrode, modified with gold nanoparticles/over-oxidized poly-eriochrome black T film, was fabricated for sensitive determination of As(III) by stripping voltammetry in an acidic medium. The electrode surface properties were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The electrode demonstrated a good response towards As(III), with a detection of 0.077 μM and good linearity in the range of 0.1 to 10 μM (R2 = 0.9977). For the determination of As(III), the fabricated electrode was placed in different mineral water samples, acidified with 0.75 M HCl solution, spiked with various concentrations of As(III). Spiked recoveries for mineral water samples were obtained in the range of 100.3%-105.0%. The relative standard deviations were lower than 4.0%.

Core/shell NiMoSe@NiMoO4 micro-cuboids anchored on Nickel foam as self-supported electrode towards efficient and stable hydrogen generation

Superaerophobic and Core-shell structured NiMoSe@NiMoO 4 micro-cuboids array for highly efficient hydrogen production. • The core–shell NiMoSe@NiMoO 4 micro-cuboids was in-situ grown on nickel foam. • The electrode surface exhibits superhydrophilic and superaerophobicity. • Se doping can improve the conductivity and catalytic activity of NiMoO 4 . • NiMoSe@NiMoO 4 shows excellent HER performance. Developing cost-effective and earth-abundant metal catalysts to act as noble metal-based catalysts substitute for highly efficient hydrogen production remain challenges. Herein, Superaerophobic and core–shell structured NiMoSe@NiMoO 4 micro-cuboids were successfully synthesized on 3D nickel foam (NF) via two-step hydrothermal method. Benefiting from the porous NF substrate, large catalytic activity area, numerous lattice defects generated in selenization process as well as superwetting and superaerophobic properties of electrode surfaces, the obtained self-supported hybrids, especially the NiMoSe@Ni 0.33 Mo 0.67 O 4 electrode presented excellent hydrogen generation performance that merely requires small overpotentials of 82.1 mV and 120.3 mV at a low and high current density of 10 mA⋅cm −2 and 50 mA⋅cm −2 in alkaline electrolyte, respectively, which is also competitive with other transition metal selenides reported literatures. Besides, the low Tafel slope of 35.23 mV⋅dec -1 and long term stability for 20 h suggesting the fast hydrogen evolution reaction kinetics and outstanding durability of electrode. This work provides a cost-effective and facile synthesis of transition metal selenides for renewable energy system.

Tailoring Surface Properties of Electrodes for Synchronous Enhanced Extracellular Electron Transfer and Enriched Exoelectrogens in Microbial Fuel Cells.

An extracellular electron transfer (EET) process between an electroactive biofilm and an electrode is a crucial step for the performance of microbial fuel cells (MFCs), which is highly related to the enrichment of exoelectrogens and the electrocatalytic activity of the electrode. Herein, an efficient N- and Fe-abundant carbon cloth (CC) electrode with the comodification of iron porphyrin (FePor) and polyquaternium-7 (PQ) was synthesized using a facile solvent evaporation and immersion method and developed as an anode (named FePor-PQ) in MFCs. The surface structural characterizations confirmed the successful introduction of N and Fe atoms, whereas FePor-PQ achieved the N content of 9.59 at %, which may offer various active sites for EET. The introduction of PQ contributed to improving the surface hydrophilicity, providing the composite electrode good biocompatibility for bacterial attachment and colonization as well as substrate diffusion. Based on the advantages, the MFC with the FePor-PQ anode produced a maximum power density of 2165.7 mW m-2, strikingly higher than those of CC (1124.0 mW m-2), PQ (1668.8 mW m-2), and FePor (1978.9 mW m-2). Furthermore, with the EET mediated by the binding of flavins and c-type cytochromes on the outer membrane was enhanced prominently, the typical exoelectrogen Geobacter was enriched up to 55.84% in the FePor-PQ anode biofilm. This work reveals a synergistic effect from heteroatom coating and surface properties tailoring to boost both the EET efficiency and exoelectrogen enrichment for enhancing MFC performance, which also provides valuable insights for designing electrodes in other bio-electrochemical systems.

The influence of electron recombination rate on the plasma characteristics in rf argon capacitive discharge

This work investigates the effect of the electron surface recombination coefficient (Ks) on radio-frequency discharge characteristics. This investigation is performed by a fluid model with the drift–diffusion approximation. The simulation results show that when the electron recombination rate is larger, the plasma density is lower in the plasma bulk region. It is found that the cycle-averaged electron and ion fluxes decrease adjacent to the electrode, while the electric potential increases in the bulk plasma region as Ks increases from 0.60 to 2.38. Moreover, the reduction in the electron density in the bulk region leads to decrease in the electron power dissipation in this region. The results also show that the electron ohmic heating and pressure heating, which play a crucial role in sustaining the discharge, can be both reduced in the sheath regions with increasing the electrons recombination rate. Finally, it is observed that the plasma characteristics can significantly be changed depending on the electrode surface properties.

Effect of protein adsorption on bioelectrochemistry of electrospun core-shell MWCNTs/gelatin-Hb nanobelts on electrode surface

Implantable electrochemical biosensor is one powerful tool for the accurate and reliable measurements of small molecules in vivo. However, the electrode is inevitably subjected to the protein adsorption when implanted into the living animals, affecting the sensitivity and stability of biosensor. Herein, we designed the multi-walled carbon nanotubes/gelatin-hemoglobin (MWCNTs/gelatin-Hb) core-shell nanobelts constructed on glassy carbon electrode (GC) using the one-step electrospinning technique for studying the effect of protein adsorption on the electrode surface properties. The results of the water contact angle and the scanning electron microscopy (SEM) showed that the electrospun core-shell MWCNTs/gelatin-Hb nanobelts present hydrophilic and certain anti-protein adsorption properties. Direct electron transfer between the Hb molecules in the electrospun core-shell nanobelts and electrode and catalysis of hydrogen peroxide (H2O2) can be still achieved after the electrospun core-shell MWCNTs/gelatin-Hb nanobelts adsorbed protein. Moreover, compared with before protein adsorption (Kmapp =0.0155 mmol/L), the electrospun core-shell MWCNTs/gelatin-Hb nanobelts after protein adsorption still displayed high biological affinity to H2O2 (Kmapp =0.0382 mmol/L). The constructed H2O2 biosensor by using the electrospun core-shell MWCNTs/gelatin-Hb nanobelts showed high sensitivity, great reproducibility and stability after protein adsorption. This study provides a novel design and an effective platform for the development of implantable electrochemical biosensors.

Cu2O−Cu2Se Mixed‐Phase Nanoflake Arrays: pH‐Universal Hydrogen Evolution Reactions with Ultralow Overpotential

AbstractMost developed hydrogen evolution reaction (HER) electrocatalysts have pH‐dependent functionalities, which limit their universal applications. Pt, the ideal HER electrocatalyst, is also highly effective in specific pH conditions. In the present article, we report a copper‐based transition‐metal chalcogenide from anion engineering. Hierarchical three‐dimensional (3D) Cu2O−Cu2Se nanoflake arrays (COCS NFs) are grown directly on nickel foam (NF) by combining the rapid electrodeposition technique with the room temperature wet‐chemical selenization method. Via the synergetic effects of the proper ratio of Se and O, as‐synthesized COCS NFs manage to accomplish key‐requirements for pH‐universal HER performances with overpotential values of 52.9, 62.8, and 77.8 mV, in alkaline, neutral, and acidic media, respectively, at 10 mA cm−2. The electrocatalyst also possesses superb stability at constant 10 mA cm−2 current density for 50 h in all electrolytes. This work offers a synthesis protocol of a mixed‐anion composite with the revelation about the importance of anion modulation towards electrode surface properties and HER performances.

Capacity Limiting Factors in Ambient Pressure Li‐Air Battery

Nonaqueous Li‐Air battery is considered to be one of the most promising future energy storage technologies due to its very high theoretical specific energy (~3.5 kWh kg⁻1) based on the reversible electrochemical reaction 2Li+ + O2 + 2e⁻ ↔ Li2O2(s); E0 = 2.96 V vs. Li/Li+. An ideal Li-Air battery breathes oxygen from ambient air continuously through the porous cathode and deposits solid lithium peroxide (Li2O2) as the discharge (DC) product until all Li metal at the anode is consumed. However, Li‐Air batteries manifest discharge capacities significantly lower than that limited by Li metal consumption and undergo a sudden death denoted by a steep decrease in potential. An enhancement in capacity has been observed when the cells are fed with oxygen instead of air but the capacity is still lower than predicted. Hence a precise understanding about the mechanism behind sudden death is a prerequisite in order to develop Li‐Air battery with high DC capacity. Unfortunately, there is lack of proper knowledge about the sudden death of Li‐Air battery under ambient oxygen pressure. So far, majority of the research on this system has been performed in pure oxygen and these studies on sudden death have come up with quite different explanations concluding that either surface passivation1 or pore clogging2 of conducting porous electrodes by insulating Li2O2 discharge product causes premature death of the cell and limits the discharge capacity. The reason behind these different opinions is the difference in Li2O2 deposition-and-growth mechanism that depends on several parameters, such as nature of the electrolytes,3 surface properties of electrodes,4 rate of DC5 etc. Additionally, oxygen partial pressure provided to the cell has also been found to influence the discharge capacity significantly.6 Taken all together, the sudden death of Li‐Air battery is the result of a complex combination of several parameters. Here we have systematically investigated the sudden death of these cells with the help of several analytical techniques under both oxygen and dry air atmospheres. Multiple stacked carbon nanotube (CNT) electrodes are used in our experiments to understand the spatial distribution of DC products in the cathode at different conditions. Scanning electron micrographs (SEM) and quantitative titration show inhomogeneous deposition of discharge products at different layers of cathode and the distribution depends on the DC rate and oxygen partial pressure. At high DC rates the fraction of Li2O2 has been found to be higher on the oxygen side of the electrodes, while at low DC rates the bulk of the electrode contains higher fraction. The DC rate at which this transition occurs, depends on the partial pressure of oxygen and usually the rate is higher for higher oxygen partial pressure. These results indicate that the limitation of oxygen diffusion through the bulk of the electrode under high DC rate and low oxygen partial pressure plays vital role behind sudden death. Based on our observations we propose that in order to achieve high discharge capacity in ambient pressure Li‐Air batteries, the air electrode should be properly designed so that oxygen diffusion is facilitated throughout the electrode.

A facile synthesis of perforated reduced graphene oxide for high performance electrochemical sensors.

Highly active perforated reduced graphene oxide (P-rGO) was synthesized by a facile methodology based on co-deposition of graphene oxide with sacrificial Prussian blue. Electrode surface properties were characterized by SEM and EDS. The GC/P-rGO electrode exhibited a larger specific surface area than that of GCE. These findings highlighted that the signal was enhanced for both dopamine detection and selenium detection by using P-rGO as a relevant supporting substrate. The result indicated that the large number of perforated structures formed numerous electrically conductive channels in the structure, improving the electrocatalytic properties.

Utilization of the catalyst layer of dimensionally stable anodes. Part 2: Impact of spatial current distribution on electrocatalytic performance

An improved general understanding of electrocatalytic gas evolution reactions may - besides contributing to fundamental knowledge - play a crucial role in efforts directed to energy savings during large-scale industrial electrocatalytic processes. Aside from the search for new electrocatalytically active materials, in-depth understanding of electrode surface properties may contribute to more efficient utilization of known electrocatalysts. SECM is applied in the sample generation/tip collection mode to determine the spatial distribution of electrocatalytic activity during Cl2 evolution at the solid/liquid interface of dimensionally stable anodes. Statistical interpretation of the local microscopic distribution of the electrocatalytic activity of dimensionally stable anodes was used as a basis for improved understanding of their overall electrocatalytic performance.

Highly activated screen-printed carbon electrodes by electrochemical treatment with hydrogen peroxide

An easy effective method for the activation of commercial screen-printed carbon electrodes (SPCEs) using H2O2 is presented to enhance sensing performances of carbon ink. Electrochemical activation consists of 25 repetitive voltammetric cycles at 10 mV s−1 using 10 mM H2O2 in phosphate buffer (pH 7). This treatment allowed us to reach a sensitivity of 0.24 ± 0.01 μA μM−1 cm−2 for the electroanalysis of H2O2, which is 140-fold higher than that of untreated SPCEs and 6-fold more than screen-printed platinum electrodes (SPPtEs). Electrode surface properties were characterized by SEM, EIS and XPS. The results revealed atomic level changes at the electrode surface, with the introduction of new carbon‑oxygen groups being responsible for improved electro-transfer properties and sensitivity. Our method was compared with other previously described ones. The methodology is promising for the activation of commercial carbon inks-based electrodes for sensor applications.