Surface Morphology Of Electrode Research Articles

Self-assembled monolayers featuring multi-chlorinated carbazole unit for improving hole extraction efficiency in organic photoelectronic device

Typical PEDOT: PSS hole-transporting layer always suffer from the unmatched energy level, harsher acidity and severe hydroscopicity, which further inducing the severe degradation of device performance and long-term stability simultaneously. Herein, we explore a novel carbazole derived molecule 4Cl-PACz as self-assembled monolayers anchoring directly onto the indium tin oxide (ITO) substrate. The 4Cl-PACz not only exhibits superior optical transmittance than PEDOT: PSS in visible and near-infrared region, but also could upgrade the work function, thus leading to more matched energy level alignment with donor materials to facilitate the hole extraction. Furthermore, 4Cl-PACz is proven to efficiently modify the surface morphology of ITO electrode while simultaneously optimizing the phase-separation of the active layer spin-coated atop. Consequently, devices based on ITO/4Cl-PACz system output a power conversion efficiency (PCE) of 16.8 % based on PM6:Y6 system. The improved performance is mainly attributed to the improvement of energy level alignment and surface morphology, thus leading to improved charge extraction, lower trap-assisted recombination and longer carrier lifetime. Encouragingly, a higher PCE of 18.2 % can be realized when PM6:L8-BO was employed as active layer. Moreover, the optimized OLED based on 4Cl-PACz also presents improved carrier transport, with enhanced luminance and efficiency values than PEDOT: PSS derived ones. This work manifests the advantage of the proposed 4Cl-PACz material for realizing high-performance and stable OSCs and OLEDs.

Perovskite solar cells on Sn-doped In2O3 electrodes with artificially controlled (222) preferred orientation

Despite the rapid advancements in transparent conductive electrodes (TCEs), most planar-type perovskite solar cells (PSCs) are still fabricated on commercial polycrystalline Sn-doped In2O3 (ITO) electrodes, due to their resulting high conductivity, transmittance, and technological mutuality. However, artificially controlling the preferred orientation of a sputtered ITO electrode through O2 partial pressure can lead to differences in the conductivity, transmittance, and surface morphology of the ITO electrode, as well as in the growth behavior of the NiOx hole transport layer and methylammonium lead iodide (MAPbI3) active layer on the ITO for high-performance planar-type PSCs. Here, we comprehensively compared the electrical, optical, structural, and morphological properties of (222) and (400) artificially preferred ITO electrodes, and we correlated the performances of the PSCs with these differently preferred ITO electrodes. The higher power conversion efficiency (17.82%) of PSCs on (222) preferred ITO electrode than that (7.98%) of PSCs on the (400) preferred ITO electrode could be attributed to the larger grain size of the MAPbI3 active layer on the (222) preferred ITO electrode with low sheet resistance (2.66 Ohm/square) and high optical transmittance (93.47%). This suggests that artificial control of the (222) preferred orientation of sputtered ITO electrode represents a simple method for improving the performance of PSCs with identical perovskite photoactive layer.

Use of Multielectrode Arrays and Statistical Analysis to Investigate the Influence of Chloride on the Pitting Probability of Copper

Under some conditions, copper and copper alloys are either immune from corrosion or undergo slow uniform corrosion, generally considered a favourable situation, since predicting the damage incurred by the metal during a period of uniform corrosion is relatively straightforward. However, under conditions leading to surface passivation of Cu, localized corrosion might occur in the presence of aggressive oxidants. As a result, the susceptibility of Cu to localized corrosion must be considered carefully to avoid unpredictable failures in Cu-based structures. Understanding the pitting probability of Cu is important for various applications, including the use of Cu-coated containers for the permanent disposal of used nuclear fuel. In this study, the pitting probability of Cu in chloride-containing solutions crudely representing the groundwater that might be found in a deep geologic repository (DGR) was investigated using electrochemical techniques and statistical analysis. The probabilities of both pitting and repassivation of Cu were found to increase with increasing [Cl-]. The surface morphologies of copper electrodes in the same solution were also evaluated using scanning electron microscopy (SEM). The passive film on the surface of the copper electrode with the highest breakdown potential (Eb) was found to be more protective than that on the electrode with the lowest Eb.

Voltammetric analysis of serotonin and epinephrine in the presence of guanine and adenine at Bismarck brown R amplified pencil graphite electrode

Simultaneous resolution of SE and EP in of AD and GU by CV and DPV at PBBR-MGPE. • Bismarck brown R (BBR) was fabricated by electropolymerisation process. • Modified electrode exhibits excellent selectivity, sensitivity and stability. • Modified Graphite pencil electrode successfully implemented for the electranalysis of serotonin and epinephrine in assistant with adenine and guanine. • Cost effective, simple and applied in electrochemical monitoring. In present study, the novel sensing platform was electrochemically designed by incorporation of Bismarck brown R (BBR) as a enhancing substance onto the graphite pencil electrode(GPE) surface and successfully implemented for the electroanalysis of serotonin(SE) and epinephrine(EP) in assistant with adenine (AD) and guanine(GU) through cyclic and differential pulse voltammetric methods(CV and DPV). The morphology of electrode surface was characterised by scanning electron microscopy (SEM). The test solutions and operating conditions such as scan rate, varied supporting electrolyte pH and concentration of targeted analytes were optimised. The electrode kinetics of a tailored sensor was governed by both adsorption and diffusion phenomenon and gives a reduced detection limits for SE and EP respectively. The configured electrode proffers the potent and persistent specificity and sensibility followed by distinctly separated four anodic signals of SE, EP, AD and GU with appreciable increments in peak currents. Therefore, the offered sensor was cost effective, simple and applied in electrochemical monitoring and biosensing applications.

Investigation of corrosion and fouling resistance of Ni–P-nanoparticles composite coating using online monitoring technology

When the temperature drops, industrial flue gases (fly ash and corrosive gases) are condensed on the surfaces of heat exchangers and easily cause operational problems such as fouling and corrosion of heat exchangers. In the present paper, an online monitoring system is established to experimentally investigate the heat transfer, fouling resistance, and corrosion resistance of different materials in coal-fired boilers under low-temperature ash deposition and dew point corrosion. The materials include ND, 316L, 2205, Ni–P, Ni–P-PTFE, Ni–P–SiO2 (50 g/L silica sol), Ni–P–SiO2 (60 g/L silica sol), and Ni–P–SiO2 (70 g/L silica sol). It was found that Ni–P coating is excellent in anti-fouling performance, and Ni–P–SiO2 coating excels in corrosion resistance. Also, the coated tubes can significantly decrease the fouling phenomenon. Comparing the electrode potential, corrosion rate, and surface morphology reveals that the tested materials can be sorted in terms of the corrosion resistance as 2205 > 316L > Ni–P–SiO2 (50 g/L silica sol) > Ni–P–SiO2 (60 g/L silica sol) > Ni–P–SiO2 (70 g/L silica sol) > Ni–P > Ni–P-PTFE > ND. Note that the performance of Ni–P–SiO2 (50 g/L silica sol) and 316L is very close. Therefore, the application of coated tubes in heat exchangers helps recover waste heat from coal-fired boilers, improve heat transfer efficiency, extend the service life of heat exchangers, and save costs.

Asymmetric Nugget Growth in Aluminum Resistance Spot Welding With Multi-Ring Domed Electrodes: An Experimental Study

Abstract Resistance spot welding of aluminum alloys (Al RSW) is known to be very challenging, in part due to the undesirable and hard-to-predict asymmetric growth of the weld nugget. In this paper, two 1.2 mm thick AA6022-T4 aluminum alloy sheets were joined by RSW using multi-ring domed (MRD) electrodes to experimentally investigate the effect of sheet surface condition, electrode surface morphology, electrode material, weld schedule, and electrode tip condition on asymmetric nugget growth, as well as the resulting weld microstructure and coach peel strength. It was found that asymmetric nugget growth was most strongly influenced by sheet surface conditions and electrode materials at the positive polarity electrode side. The asymmetric nuggets exhibited a smaller nugget angle in relation to the faying surface and a wider partially melted zone (PMZ) in the sheet adjacent to the negative electrode which reduced weld mechanical strength and toughness. In addition, the asymmetric nugget growth also caused asymmetric electrode/workpiece interaction.

Comparative study on sensing and optical properties of carbazole linked novel zinc(II) and cobalt (II) phthalocyanines

In the current work, symmetrically carbazole linked Zn(II) and Co(II) phthalocyanines (Pcs) have been succesfully synthesized and characterized through Fouirer Transform Infrared (FT-IR), Ultraviolet–visible (UV–vis) spectroscopies, Matrix-assisted laser desorption - ionisation-time of flight mass spectrometry (MALDI-TOF MS) along with proton and carbon Nuclear Magnetic Resonance (1H and 13C- NMR) spectroscopies. The electrochemical performance of the targeted metallo- phthalocyanines was demonstrated with cyclic voltammetry (CV), and square wavevoltammetry (SWV). The final phthalocyanines were used as hybrid materials for the preparation of the modified glassy carbon electrode (GCE). The hybrid materials were then deposited on GCE via an electropolymerization or electrodeposition method. The surface morphologies of the hybrid electrodes were investigated using scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDX). IR, UV–vis and Raman spectroscopies were carried out to evaluate the surface of the hybrid electrodes. The N-ethylcarbazole moiety and redox active Zn(II), Co(II) metal centers were employed in order to improve the sensing performance of targeted compounds. Furthermore, hybrid material-graphene modified GCEs have been designed to compare and rise the analytical activity. The sensing properties of the designed electrodes was investigated to detect electrochemically active biomolecules namely, dopamine (DA), ascorbic acid (AA), and uric acid (UA) in both phosphate buffered saline (PBS) and tap water sample. The Grp/ Ply(Car-CoPc)/GCE electrode was only detected DA with a limit of detection (LOD) of 16 nM. On the other hand, LOD values of Grp(Car-CoPc)/GCE were determined by voltammetric analyses as 3.38 μM and 0.62 μM for AA and UA, respectively. Sensing performances of the designed electrodes were eximined for the concurrently determination of DA and UA using differential pulse voltammetry (DPV) method.

Lead-modified graphite felt electrode with improved [formula omitted] electrochemical activity for vanadium redox flow battery

Graphite felt is disadvantageous of lower electrochemical reaction activity, which is improved by introducing catalysts. Especially, cheaper materials and simple fabrication are popular for reducing cost. In this work, electrodeposited-lead electrode is proposed for improving electrochemical reaction activity of VO2+/VO2+ couple as well as charge-discharge performance of the battery. Experiment platform is established for vanadium redox flow battery. Cyclic voltammetry and charge-discharge performance measurements are carried out. Electron scanning microscope (SEM) is employed to investigate the surface morphology of electrode. Results show that peak potential difference (ΔE+) and peak current ratio (Ia+/Ic+) with electrodeposited-lead electrode is 103.7 mV lower and 0.249 lower than that with untreated electrode for VO2+/VO2+ electrochemical reaction. Electron scanning microscope images exhibit that lead particles are adhered extensively on carbon fiber of electrodeposited-lead electrode, which improves electrochemical activity of VO2+/VO2+ couple. Energy efficiency of the battery with electrodeposited-lead electrode in positive side is higher than that with untreated electrode by 8.5% at 60 mAcm−2. Electrodeposited-lead electrode exhibits higher activity to VO2+/VO2+ reaction and brings about higher energy efficiency of battery. This work provides a suitable electrode for vanadium redox flow battery.

Tailoring the metal electrode morphology via electrochemical protocol optimization for long-lasting aqueous zinc batteries

Aqueous zinc metal batteries are a viable candidate for cost-effective energy storage. However, the cycle life of the cell is adversely affected by the morphological evolution of the metal electrode surface upon prolonged cycling. Here, we investigate different electrochemical protocols to favour the formation of stable zinc metal electrode surface morphologies. By coupling electrochemical and optical microscopy measurements, we demonstrate that an initial zinc deposition on the metal electrode allows homogeneous stripping and plating processes during prolonged cycling in symmetric Zn||Zn cell. Interestingly, when an initially plated zinc metal electrode is tested in combination with a manganese dioxide-based positive electrode and a two molar zinc sulfate aqueous electrolyte solution in coin cell configuration, a specific discharge capacity of about 90 mAh g−1 can be delivered after 2000 cycles at around 5.6 mA cm−2 and 25 °C.

Critical Role of Pits in Suppressing Li Dendrites Revealed by Continuum Mechanics Simulation and In Situ Experiment

Dendrite growth and surface pitting are critical factors hindering the development of ultra-high energy density rechargeable lithium battery. However, the mechanism of dendrite growth promoted by pits on the surface of lithium metal remains unclear. In this study, we propose a combination of continuum mechanics simulations and develop an in situ experimental observation device to investigate the effects of pit size, curvature of pit edge, overpotential, and lithium-ion concentration gradient on dendrite growth. Results show that a larger size and curvature of pits can reduce the deposition rate of lithium and dendrite morphology significantly. Larger overpotential can aggravate dendritic nucleation and thereby promotes dendrite growth. Uneven lithium-ion concentration gradient distribution significantly influences the direction of the dendrite growth and leads to the formation of branches. The lithium deposition behavior near the ideal pit predicted by continuum mechanics is consistent with that observed in the in situ experiments. These results lay the basis for future studies to determine the effect of the surface morphology of lithium metal electrodes on the electrodeposition stability and performance of lithium metal batteries.

Use of Multielectrode Arrays and Statistical Analysis to Investigate the Pitting Probability of Copper. Part I: The Effect of Chloride

Under some conditions, copper and copper alloys are either immune from corrosion or undergo slow uniform corrosion, generally considered a favourable situation, since predicting the damage incurred by the metal during a period of uniform corrosion is relatively straightforward. However, under conditions leading to surface passivation of Cu, localized corrosion might occur in the presence of aggressive oxidants. Therefore, the susceptibility of Cu to localized corrosion must be considered carefully to avoid unpredictable failures in Cu-based structures. Understanding the pitting probability of Cu is important for various applications, including the use of Cu-coated containers for the permanent disposal of used nuclear fuel. In this study, the pitting probability of Cu in chloride-containing solutions crudely representing the groundwater that might be found in a deep geologic repository (DGR) was investigated using electrochemical techniques and statistical analysis. The probabilities of both pitting and repassivation of Cu were found to increase with increasing [Cl−]. The surface morphologies of copper electrodes in the same solution were also evaluated using scanning electron microscopy (SEM). The passive film on the surface of the copper electrode with the highest breakdown potential (Eb) was found to be more protective than that on the electrode with the lowest Eb.

Mesoporous TiO2 @ Fe metal organic framework nanocomposite for an efficient chlorpyrifos detection and degradation

We report a sensitive voltammetric sensor for chlorpyrifos based on TiO2@Fe-imidazole MOF nanocomposite through hydrothermal process modified glassy carbon, screen printed carbon and graphene electrodes (MGCE, MSPCE & MSPGE). The electrode surface morphology and enhancement study was performed through SEM, electrochemical impedance spectroscopy Randels fit analysis and the results revealed that the TiO2@Fe-imidazole MOF modified electrodes reduced the resistance of the redox probe, which helps to promote the sensing ability and electro oxidation behaviour of chlorpyrifos. A voltammetric result revealed that the TiO2@Fe-imidazole MOF at MGCE, MSPCE and MSPGE detects potential at 8.91E−07:0.161 V, 2.52E−06; 0.26 V and 4.86E−06; 0.322 V respectively. The developed sensor exhibits low detection limit of 10 pg/drop through DROPSENS and revealed excellent degradation efficiency through spectroelectrochemical degradation of chlorpyrifos with TiO2@Fe-imidazole MOF. The real time drop sensing of TiO2@Fe-imidazole MOF at modified electrodes performed with real samples exhibits good sensitivity and selectivity towards chlorpyrifos. Hence, this characteristic of MOF helps to improve the futuristic environmental applications at one drop.

Highly Porous Gold Electrodes – Preparation and Characterization

AbstractGold screen printed electrodes (Au‐SPEs) were treated electrochemically to produce a micro‐rough pattern increasing the real electrode surface. The procedure based on the Dynamic Hydrogen Bubble Template (DHBT) method included electrochemical deposition of Au layers onto the surface of the Au‐SPEs, followed by a reductive process at −3 V (vs. Ag/AgCl) leading to formation of H2 bubbles, which produced pores in the Au multilayer. The morphology of the micro‐porous Au electrode was characterized by scanning electron microscopy (SEM), surface mapping, surface profilometry, and confocal microscopy. The electrode surface morphology was controlled by the time of the electrode reductive treatment (H2 evolution) and the optimized condition resulting in the best surface structuring was found. Notably, the surface roughness leading to the highest electrode surface area was significantly increased compared to previously reported results with Au‐SPEs.

Effect of annealing process parameters on N-GaAs ohmic contacts

Ni/Ge/Ni/Au multi-layer metal electrodes were prepared on N-GaAs substrate by electron-beam evaporation to investigate the effect of annealing process parameters on N-GaAs ohmic contacts. In the annealing temperature range of 370 °C to 430 °C, the metal-semiconductor contact was found changing from Schottky contact to ohmic contact as the annealing temperature was above 380 °C. Specific contact resistivity of n-GaAs samples firstly decreased and then increased with the increasing of annealing temperature, and the minimum specific contact resistivity of 3.3 × 10−5 Ω·cm2 was formed at 420 °C annealing for 80 s. Although the specific contact resistivity of the metal-semiconductor contact performed satisfactorily, the surface morphology of the n-GaAs metal electrode was found having metal shrinkage after annealing. The formation mechanism of ohmic contact was qualitatively explained by the elements diffusion under different annealing parameters, which were confirmed by the comparative analysis of SEM and EDX results.

Investigation on a Self-Breakdown Repetitive Gap Switch Based on the Graphite Electrodes With TiC Surface Modification

In this article, a self-breakdown repetitive gap switch based on the graphite electrodes with surface modified by TiC is investigated to improve the scattering of the breakdown voltage. The self-breakdown repetitive gap switch was experimentally studied with the graphite electrodes and two kinds of TiC modified graphite electrodes (hereinafter referred to as TiC-I electrodes and TiC-II electrodes). Results show that the scatterings of the breakdown voltages of the graphite, TiC-I and TiC-II electrodes were 2.49%, 1.80%, and 1.54%, respectively. Compared with the graphite electrodes, the mass losses of TiC-I and TiC-II electrodes are reduced by 50% and 68%. The influence of electrode surface morphology on the switch stability is analyzed based on the mechanism of switch conduction process. Compared with the graphite electrodes, the electric field amplification coefficients of TiC-I and TiC-II electrodes are more evenly distributed, which leads to the more evenly distributed field emission current density. Thus, the breakdown areas of TiC-I and TiC-II electrodes are smaller and the gas breakdown processes are more stable than those of the graphite electrodes, resulting in smaller scattering of the breakdown voltage. The method that decreases the scattering of the breakdown voltage and reduces the mass loss of the electrodes by modifying graphite electrodes surface can greatly improve the stability of the switch, which is of significance to the application of the switch in the compact, long time stable operation of high-power pulse power devices.

Hemicellulosa-derived Arenga pinnata bunches as free-standing carbon nanofiber membranes for electrode material supercapacitors

Carbon nanofibers derived from lignocellulosic materials have become the most prevalent free-standing electrode material for supercapacitors due to their renewable and sustainable nature. This study used Arenga pinnata bunches (APB) as raw material for hemicellulose compounds to produce carbon electrodes through carbonization processes at 650 °C, 700 °C, 750 °C, and 800 °C, in the presence of flowing N2 gas. The variations in carbonization temperature resulted in carbon electrodes with surface morphology having a nanofiber structure with micro-meso pore distribution. According to the results, the carbonization temperature of 700 °C (APB-700) is the optimum temperature for producing electrode surface morphology with a combination of nanofiber, micro-and mesopore distributions, as well as specific surface area, specific capacitance, energy density, and power density of 1231.896 m2 g−1, 201.6 F g−1, 28.0 Wh kg−1, and 109.5 W kg−1, respectively, for the two electrode systems. This shows the combination of nanofibers and the distribution of micro-and mesopores produced with variations in carbonization temperature has the capacity to improve the performance of supercapacitor cells. Therefore, carbon nanofibers derived from Arenga pinnata bunches have the potential to be used as free-standing electrode materials for supercapacitors without employing doping, binder, electrospinning, and heteroatom template methods.

Chemical Etching of Cu98Be Alloy in Electrolyte Solutions

The process of chemical etching of Cu98Be alloy in solutions of various compositions was investigated. The rate of etching of beryllium bronze in the investigated solutions was deter-mined, and its change in time was studied. The selectivity of dissolution of the components of Cu98Be during prolonged etching in solutions of different electrolytes was established. A possibility of achieving uniform etching of Cu98Be alloy by varying the composition of the etching solution was shown. The concentrations of metal ions in the used etching solutions were determined, and the capacity of those solutions was calculated. The compositions of solutions with a high capacity for both alloy components during prolonged etching was estab-lished. The optimal compositions of etching solutions providing high-quality etching of beryl-lium bronze according to several criteria such as: a high process rate, uniform dissolution of alloy components, high capacity for both alloy components were proposed. The morphology of the Cu98Be electrode surface after etching in solutions, providing uniform dissolution for both alloy components, was studied. The absence of surface passivation after chemical etch-ing in these solutions was shown. The chemical nature of the compounds formed in the form of small inclusions on the etched surface of the electrode was established. The obtained results are of great importance in practical use because they allow selecting the appropriate composition of the etching solution, which, in turn, helps to optimize the technological etching process.

Homogenization of electric field distribution facilitating the Zn anode reversibility.

The surface morphology of the zinc-metal electrode was modulated using different levels of physical polishing treatment. Modulating the surface scratches homogenized the deposition electric field and reduced the local current density. A reasonable surface treatment could limit the "tip effect" and bring homogeneous plating and stripping of the Zn electrode.

Cathodic corrosion of Au in aqueous methanolic alkali metal hydroxide electrolytes: Notable role of water

AbstractCathodic corrosion is an electrochemical process that induces restructuring, roughening, and etching of metal surfaces at a highly negative surface charge density, yet, details of the reaction mechanism are not fully resolved. An in‐depth fundamental understanding of the processes and parameters underlying cathodic corrosion is crucial for tailoring the surface structure of the metal electrodes and for synthesizing shape‐ and size‐controlled nanoparticles. Here, we investigate the relevance of water and hydrogen evolution in the cathodic corrosion process. To achieve this aim, Au electrodes were polarized at ‐1.6 V versus RHE in KOH and NaOH electrolytes prepared using different water + methanol mixtures. Structural changes of the Au surfaces were studied by cyclic voltammetry and monitored by scanning electron microscopy (SEM). Most importantly, cathodic corrosion does not take place in the absence of water. There is no detectable bubble formation due to the hydrogen evolution reaction on Au in purely methanolic alkali. Furthermore, the electrochemically active surface area, facet distribution, and surface morphology of Au electrodes are significantly altered upon cathodic polarization as a function of the water concentration. Cathodic corrosion features become more and more pronounced with a further increase in water content. In addition, substantial differences in the surface structure of Au are observed as a function of the nature and concentration of alkali metal cations. Overall, this study provides a more detailed understanding of the role of water and the hydrogen evolution reaction in dominating cathodic corrosion, which might advance the understanding of this phenomenon.

The inhibition tendencies of novel hydrazide derivatives on the corrosion behavior of mild steel in hydrochloric acid solution

Three different simple and polymeric hydrazide derivatives have been synthesized, evaluated and investigated as corrosion inhibitors for mild steel in 1 M hydrochloric acid medium. The corrosion inhibition performance of these additives was evaluated using electrochemical impedance spectroscopy (EIS) and polarizations measurements. The inhibition efficiency obtained from polarization measurement followed the order of PACAH > ACAH > CAH. The inhibition efficiency of the polyhydrazide derivative (PACAH) at concentration of 50 and 500 ppm was found to be 90.66 and 96.79% respectively, while 500 ppm of cyanoacetohydrazide (CAH) was 39.79% and for the monomer N-acryloyl-N′-cyanoacetohydrazide (ACAH) was 88.66%.The surface morphology of the steel electrode was studied with and without the inhibitor after immersion in 1 M HCl solution for 6 h using SEM, EDAX and AFM measurements. The results showed an improvement in the surface morphology where the flawed regions were repaired and the cracks were healed. This improvement was attributed to the adsorption of the inhibitor molecules and the formation of a protective layer at the steel surface. The adsorption isotherm indicated a spontaneous physical adsorption of the inhibitor on the surface of mild steel electrode. Quantum chemical calculation was used to correlate the inhibition efficiencies data of the hydrazide derivatives with their electronic structural parameters. Theoretical calculations supported and elucidated the experimental results.