Open Circuit Potential Conditions Research Articles

Comparison of tribological and corrosion characteristics of AISI 316Ti and AISI 430 stainless steels

Abstract This study presents an investigation into the tribological, corrosion, and tribocorrosion properties of AISI 316Ti (austenitic) and AISI 430 (ferritic) stainless steels. The comparative analysis focuses on microstructural characterization, hardness, and a series of tribological, electrochemical, and tribocorrosion tests conducted in 0.9% NaCl using a specialized linear tribometer to reveal the quality of the studied materials in tribocorrosion applications. Friction tests were performed under both dry and corrosive conditions, while tribocorrosion tests were conducted under open circuit potential (OCP) conditions in 0.9% NaCl, with the electrode potential of the test specimen monitored during friction. To evaluate the electrochemical behavior of the materials, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were conducted using a 0.9% NaCl solution. The measured corrosion potential (Ecorr) suggests that AISI 430 is thermodynamically more stable than AISI 316Ti; however, AISI 316Ti demonstrated higher polarization resistance (RP) values compared to AISI 430. The findings indicate that material qualities significantly influence the coefficient of friction (CoF). Additionally, a notable antifriction effect of 0.9% NaCl was observed during tribological testing, resulting in a lower CoF compared to dry friction conditions. A cathodic shift in OCP during tribocorrosion testing was also observed in both materials, indicating an increase in corrosion vulnerability when the passive layer is degraded.

Effect of Al/Cr ratio on structure, magnetism, and corrosion resistance of FeCoNiCr1-xAlx high entropy alloys

This study investigates the microstructure, magnetic properties, and corrosion resistance of FeCoNiCr1-xAlx (x=0, 0.25, 0.5, 0.75, 1) high-entropy alloys using the combination of experimental methods and first-principles calculations. XRD results reveal the FCC-BCC phase transition as x increases, and FeCoNiCr1-xAlx exhibits a noticeable dual-phase structure when x=0.75. The partial segregation between Ni and Al elements is indicated by SEM-EDS observations. The magnetism of both FCC and BCC phases become strong with increasing x, and the BCC phase consistently exhibiting higher magnetism than the FCC phase. Potentiodynamic polarization curves show that Al0.25 has the highest corrosion potential and the lowest corrosion current density. Under open circuit potential conditions, due to the difference between the corrosion potential and the open circuit potential, the electrochemical impedance spectroscopy measurements indicate that the corrosion resistance of the alloys follows the order: Al0 > Al0.5 > Al0.75 > Al0.25 > Al1. Considering both the soft magnetic behavior and corrosion resistance, Al0.75 is a optimal choice. These findings provide valuable insights for developing magnetic high-entropy alloy materials with superior corrosion resistance.

Kinetic analysis of the self-discharge of the NiOOH OER active phase in KOH electrolyte: insights from in-situ Raman and UV–Vis reflectance spectroscopies

NiOOH has been established as the active phase of NiO-based electrocatalysts in the alkaline Oxygen Evolution Reaction (OER). Here, we investigate the self-discharge behavior of NiOOH electrodes under open circuit potential (OCP) conditions in 1 M KOH electrolyte by monitoring phase changes via in-situ Raman and UV–Vis reflectance spectroscopies and performing kinetic analyses on the OCP and spectroscopic data. Our findings reveal a linear phase change from NiOOH to Ni(OH)2 over time, indicative of a 0th-order reduction reaction. Contrarily, the OCP evolution associated with this phase reduction displayed a combination of linear and exponential decay patterns as a result of various kinetics, including Faradaic processes and diffusion-controlled mechanisms, influencing the self-discharge potential over 1.25 V (vs RHE). An additional linear region at lower potentials (<1.25 V (vs RHE)) suggests that charge redistribution due to the phase change from α-Ni(OH)2 to β-Ni(OH)2 dominates the self-discharge, a behavior confirmed by in-situ UV–Vis reflectance spectroscopy. These findings highlight the effectiveness of combining in-situ Raman and UV–Vis spectroscopy with electrochemical data for real-time monitoring of electrochemical processes, here potential-dependent electrocatalyst phase changes, leading to a more detailed and accurate understanding of the dynamic behavior, phase change kinetics, and self-discharge behaviors of solid electrocatalysts that can guide the design of more efficient and durable energy storage and conversion materials.

Reconfiguration of organic electrochemical transistors for high-accuracy potentiometric sensing

Organic electrochemical transistors have emerged as a promising alternative to traditional 2/3 electrode setups for sensing applications, offering in-situ transduction, electrochemical amplification, and noise reduction. Several of these devices are designed to detect potentiometric-derived signals. However, potentiometric sensing should be performed under open circuit potential conditions, allowing the system to reach thermodynamic equilibrium. This criterion is not met by conventional organic electrochemical transistors, where voltages or currents are directly applied to the sensing interface, that is, the gate electrode. In this work, we introduce an organic electrochemical transistor sensing configuration called the potentiometric‑OECT (pOECT), which maintains the sensing electrode under open circuit potential conditions. The pOECT exhibits a higher response than the 2-electrode setup and offers greater accuracy, response, and stability compared to conventional organic electrochemical transistors. Additionally, it allows for the implementation of high-impedance electrodes as gate/sensing surfaces, all without compromising the overall device size.

Stress-Corrosion-Cracking Sensitivity of the Sub-Zones in X80 Steel Welded Joints at Different Potentials.

X80 steel plays a pivotal role in the development of oil and gas pipelines; however, its welded joints, particularly the heat-affected zone (HAZ), are susceptible to stress corrosion cracking (SCC) due to their complex microstructures. This study investigates the SCC initiation mechanisms of X80 steel welded joints under practical pipeline conditions with varying levels of cathodic protection. The SCC behaviors were analyzed through electrochemical measurements, hydrogen permeation tests, and interrupted slow strain rate tensile tests (SSRTs) conducted in a near-neutral pH environment under different potential conditions (OCP, -1.1 VSCE, -1.2 VSCE). These behaviors were influenced by microstructure type, grain size, martensite/austenite (M/A) constituents, and dislocation density. The sub-zones of the weld exhibited differing SCC resistance, with the fine-grain (FG) HAZ, base metal (zone), welded metal (WM) zone, and coarse-grain (CG) HAZ in descending order. In particular, the presence of coarse grains, low dislocation density, and extensive M/A islands collectively increased corrosion susceptibility and SCC sensitivity in the CGHAZ compared to other sub-zones. The SCC initiation mechanisms of the sub-zones within the X80-steel welded joint were primarily anodic dissolution (AD) under open-circuit potential (OCP) condition, shifting to either hydrogen-enhanced local plasticity (HELP) or hydrogen embrittlement (HE) mechanisms at -1.1 VSCE or -1.2 VSCE, respectively.

Tribocorrosion behaviour of additively manufactured β-type Ti–Nb alloy for implant applications

β-type Ti–Nb alloys are promising materials for load-bearing implant applications with improved mechanical biofunctionality and biocompatibility. In this work, the electrochemical and tribo-electrochemical behaviour of laser powder bed fusion (LPBF) produced β-type Ti–42Nb alloy processed via Gaussian and top hat laser was investigated and compared with commercial grade β-type Ti–45Nb and α+β-type Ti–6Al–4V ELI. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization experiments were performed in phosphate-buffered saline (PBS) for corrosion behaviour. Tribocorrosion behaviour was studied under open circuit potential (OCP) conditions in PBS by using a reciprocating pin-on-disk tribometer. The passivation nature of the LPBF alloys is more decisive than the microstructural particularities for electrochemical behaviour. The overall corrosion response is similar due to the protective nature of the passive films formed on Ti alloys. Ti–6Al–4V ELI exhibits the best corrosion performance among all tested alloys with lower corrosion and passivation current density values. However, LPBF-produced alloys exhibit less reactive surfaces with better passive film properties compared to Ti–45Nb. In addition, EIS results revealed that passive film resistance values are higher for LPBF-produced alloys than conventionally produced Ti–45Nb. LPBF-produced alloys exhibit better tribo-electrochemical behaviour compared to Ti–45Nb. The differences in volume loss are mainly attributed to the microhardness of the alloys and the volume loss is dominated by mechanical wear. The alloys produced with LPBF show promising corrosion and tribocorrosion performance to be a potential candidate for load-bearing implant applications.

Nano Scale Poly(vinylidene chloride-co-acrylonitrile) Protection for Reversible and Stable Mg Anode Interface

This study investigates the efficacy of a polymer coating, PVdC-co-AN, in enhancing the stability and reversibility of the electrochemical Mg anode interface. Coated electrodes, immersed in a 0.25 M Mg(TFSI)2−0.50 M MgCl2/dimethoxyethane (DME) electrolyte, exhibit notable improvements. Cyclic voltammetry demonstrates consistent behavior with the coated electrode, while the uncoated electrode changes dramatically. During extended open circuit potential conditions, the coated electrode maintains much higher coulombic efficiency (93%) compared to the uncoated electrode (62%). Galvanostatic cycling test over 200 cycles further show the benefits of the PVdC-co-AN coating, decreasing the overpotential of Mg plating and improving long-term stability. The coated electrodes also demonstrate improved rate capability at higher current densities. Surface analysis reveals differences in the formation of byproducts between the coated and uncoated electrodes, indicating a more stable and uniform interface in the former. Nuclear magnetic resonance (NMR) spectroscopy suggests that the polymer influences ion mobility through tuning the solvation environments which results in better kinetics and fewer byproducts. In summary, the study affirms that the PVdC-co-AN coating significantly improves the stability and performance of Mg electrochemistry, offering a promising advancement for practical battery applications.

Electrochemical determination of carbendazim in juice samples using carbon composite electrode modified with ion‐exchange resin

AbstractThis work describes a carbon composite modified electrode (CCME) easily prepared using a simple mixture of a commercial cation exchange resin (Amberlite IR 120H) as modifier, graphite powder and paraffin, which was successfully used for spontaneous preconcentration and voltametric determination of carbendazim (CBZ) in juice samples. Parameters such as amount of resin used in the composition of the electrode, pH and preconcentration time as well as instrumental parameters of differential pulse voltammetry (DPV) were studied. Under optimized conditions, the proposed sensor shows to be able to preconcentrate CBZ at an open circuit potential (OCP) condition and presented the highest analytical response in comparison to the unmodified electrode. An analytical curve was obtained for the CBZ determination employing the proposed CCME and showed a linear dynamic range (LDR) between 80.0 nmol L−1 to 2.0 μmol L−1, with a LOD of 19 nmol L−1 and LOQ of 65 nmol L−1. The effect of concomitants on the voltametric response was evaluated by addition and recovery study and a good selectivity was found. The proposed sensor was successfully applied for the determination of CBZ in spiked mango juice samples without any pretreatment.

A micro-alloyed Mg-Zn-Ge alloy as promising anode for primary Mg-air batteries

Alloying is one of the effective approaches to boost the discharge property of magnesium (Mg) anodes for primary Mg-air batteries and recently micro-alloying is highly recommended at the aim of developing advanced primary Mg system. In this study, micro-alloyed extruded Mg0.5Zn0.2Ge (in wt.%) alloy is evaluated as an anode candidate for primary Mg-air batteries in both half-cell and Mg-air full cell configurations, in comparison with commercially accepted Mg anodes, typified by as-cast HP Mg and extruded AZ31 alloy. The corrosion behavior at open circuit potential (OCP) condition of the three materials is also compared through electrochemical tests. Mg0.5Zn0.2Ge alloy displays the most negative OCP value and the highest corrosion resistance at OCP. During discharge, Mg0.5Zn0.2Ge anode exhibits low wasteful-discharge rate and homogeneous dissolution that gives rise to the absence of “chunk effect”. Consequently, the anodic efficiency and specific capacity of Mg0.5Zn0.2Ge anode are superior to those of HP Mg and AZ31 anodes, e.g. 57.3% and 1257 mAh g−1 at 1 mA cm−2. Additionally, Mg-air battery based on Mg0.5Zn0.2Ge anode offers higher cell voltage and specific energy than those assembled with HP Mg and AZ31 anodes, which can be further optimized by addition of electrolyte additives. Therefore, micro-alloyed Mg0.5Zn0.2Ge alloy can serve as a promising candidate for anode material of primary Mg-air batteries.

In vitro tribocorrosion evaluation of carbide-derived carbon (CDC) for hip implants

ABSTRACT Carbide-derived carbon (CDC) was previously proposed as a surface modification method for hip implant applications since it showed excellent tribocorrosion performance under open-circuit potential (OCP) conditions. Nonetheless, a systematic evaluation of the CDC’s tribocorrosion properties was still missing. Therefore, our objective is to test CDC’s tribocorrosion performance under various electrochemical conditions and to identify the synergism between wear and corrosion. Based on the findings, the variations in OCP for CDC (0.626 mV) are smaller than Ti6Al4V (1.91 mV), and CDC showed lower induced current than T6Al4V for all potentials, suggesting CDC is more stable than Ti6Al4V under tribocorrosive conditions. Eventually, the weight loss of Ti6Al4V (50.662 ± 5.19 μg) was found to be significantly higher than that of CDC (4.965 ± 5.19 μg), which agrees with the electrochemical results. In summary, CDC showed better tribocorrosion performance than Ti6Al4V and was determined as an Antagonism regime.

Influence of isothermal tempering on microstructures and hydrogen-environmentally embrittlement susceptibility of laser additively manufactured ultra-high strength AerMet100 steel

Good hydrogen-environmentally embrittlement (HEE) resistance is necessary for safe service of critical main load-bearing ultra-high strength steel (UHSS) components of advanced aircrafts in marine atmosphere environment. Controlling isothermal tempering time is one important heat treatment method to optimize HEE resistance of UHSS by designing microstructure. Influence of isothermal tempering time at 482 °C on microstructures and HEE susceptibilities of laser additively manufactured (LAM) AerMet100 steel was investigated by several material characterization methods and slow strain rate tensile (SSRT) tests in both of air and 3.5 wt% NaCl aqueous solution. Results mainly indicate that microstructure evolution behaviors of LAM AerMet100 steel successively include martensite and retained austenite decomposition, M2C carbide formation and coarsening, and film-like reverted austenite formation and thickening. Short-time tempering specimens of LAM AerMet100 steel has the highest strength-loss-index in all of the specimens due to the lowest austenite amount. The lower HEE susceptibility of LAM AerMet100 steel in long-time tempering condition is mainly corresponding to M2C carbide coarsening and film-like reverted austenite thickening. Furthermore, difference of hydrogen charging method strongly influences macro-fracture behaviors of the SSRT specimens, but micro-cracking modes of the steel in different conditions are predominantly martensite packet/plate boundary cracking. Under open-circuit potential condition, HEE cracking zone is prone to be origin from pitting corrosion sites, and the SSRT specimen in long-time tempering condition have a good ductility; in contrast, under cathodic polarization condition, HEE cracking zone is around the circumferential zones, and the tensile specimens are brittle fracture. These findings are important when considering achieving improved HEE resistance for LAM AerMet100 steel tempered at 482 °C of a longer isothermal tempering time at the strength level of interest.

Mechanistic Aspects and Side Reactions during Reversible Mg Deposition and Oxygen Reduction on a Pt Film Electrode in BMP‐TFSI‐Based Electrolytes: A DEMS Study

AbstractReversible Mg deposition/stripping and O2 reduction/evolution on a Pt film electrode in neat and O2‐saturated 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMP‐TFSI) electrolytes, containing Mg(TFSI)2 and/or Mg(BH4)2 as Mg source as well as Mg(BH4)2 and/or the crown ether 18‐c‐6 as additive, were investigated by online differential electrochemical mass spectrometry (DEMS) and by scanning electron microscopy/energy dispersed X‐ray spectroscopy. Combined cyclic voltammetry and DEMS measurements reveal a complex network of partial reactions, including borohydride electro‐oxidation by reaction with water or O2, chemical bulk reaction of these components, as well as electro‐oxidation of H2, and electrolyte decomposition, in addition to the primary reactions Mg deposition/stripping and ORR/OER. They provide detailed insights into the potential dependent reactions occurring under these conditions, demonstrating that also the additive 18‐c‐6 undergoes decomposition upon reduction of Mg2+. Contributions from chemical bulk reactions are resolved by DEMS measurements in borohydride containing solution without a Pt electrode. Electrocatalytic borohydride oxidation, explored by similar measurements with a Pt electrode, can lead to H2 or H+ formation. Under open circuit potential conditions, charge compensation by the ORR results in the formation of a mixed potential. Consequences of these findings for applications in Mg‐air batteries are discussed.

Electrochemical and passivation behavior of a corrosion-resistant WC-Ni(W) cemented carbide in synthetic mine water

Two different grades, WC-20 vol.% Ni and WC-20 vol.% Co cemented carbides, respectively were systematically investigated concerning their microstructure, binder composition, and corrosion behavior. SEM-EBSD analysis verified that both grades have similar WC grain sizes (0.9–1.1 μm). AES analysis confirmed that the binder phase of the respective grade is an alloy of Ni-W and Co-W and that the concentration of W in the Ni- and Co-binder is 21 and 10 at. %, respectively.In synthetic mine water (SMW), the EIS behavior of WC-Ni(W) at the open circuit potential (OCP) conditions was studied for different exposure periods (up to 120 h). The EIS data fitting estimates low capacitance and high charge transfer resistance (Rct) values, which indicate that the passive film formed on WC-Ni(W) is thin and exhibits high corrosion resistance. At the OCP and potentiostatic-passive conditions, SEM investigations confirm the uncorroded microstructure of the WC-Ni(W). The AR-XPS studies confirmed the formation of an extremely thin (0.25 nm) WO3 passive film is responsible for the high corrosion resistance of WC-Ni(W), at OCP conditions. However, above the transpassive potential, the microstructure instability of WC-Ni(W) was observed, i.e., corroded morphology of both WC grains and Ni(W) binder. The electrochemical parameters, Rct, corrosion current density, and charge density values, confirmed that the WC-Ni(W) is a far better alternative than the WC-Co(W) for application in SMW.

Studies of Bis-(Sodium-Sulfopropyl)-Disulfide and 3-Mercapto-1-Propanesulfonate on/into the Copper Electrodeposited Layer by Time-of-Flight Secondary-Ion Mass Spectrometry

Interactions of functional additives SPS (bis-(sodium-sulfopropyl)-disulfide), MPS (3-Mercapto-1-Propanesulfonate), and Cl accumulated and incorporated on/into a copper electrodeposited layer were studied using time-of-flight secondary-ion mass spectrometry (TOF-SIMS) in combination with cyclic voltammetry measurements (CV). It was shown that the Cl and MPS surface coverage is dependent on the applied overpotential and concentration of Cl, SPS, or MPS in the solution. Detailed discussion on the mechanism of yielding CH2SO3-, C3H5SO3-, CuSC3H6SO3-, and CuS- fragments and their assignment to the gauche or trans conformation was proposed. The mechanism of the process of incorporation and re-adsorption of MPS on/into a copper surface under electrochemical conditions without and with chloride ions and its impact on electrochemical properties was proposed. Moreover, it was shown that the presence of chloride ions, the ratio gauche/trans of MPS molecules, as well as the ratio chloride/thiols demonstrate a high impact on the accelerating abilities. Comparative studies conducted under open circuit potential conditions on the nitinol and copper substrate allowed for the identification of specific reactions/interactions of MPS, or SPS and Cl ions on the nitinol and copper surface.

Growth Kinetics of Calcareous Deposits on Thermally Sprayed Aluminum Coatings in Natural Seawater

The formation of calcareous deposits on thermally sprayed aluminum (TSA)-coated surfaces immersed in natural seawater and connected to a cathodic protection system is a recurring issue. There is at present limited knowledge on the calcareous deposits’ formation kinetics on TSA in natural seawater following prolonged exposure at different temperatures. In this study, bare 25Cr super-duplex stainless steel (SDSS) and TSA-coated SDSS tube coupons (with and without a silicone-based sealer) were exposed to natural seawater under potentiostatic cathodic protection (CP) and open-circuit potential (OCP) conditions at different temperatures (i.e., 20°C, 35°C, 60°C, and 80°C) for 1.5 y. The coupons were extracted at various intervals to construct growth kinetics curves under various test conditions. The deposits were subsequently examined using scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction. For all of the specimens, the deposits on the exposed surfaces increased with exposure time. Fewer deposits were seen under CP conditions than OCP at low temperatures (20°C and 35°C), whereas more deposits were observed with CP than those at OCP at high temperatures (60°C and 80°C). Last, a recommended protection potential of −0.90 VSSC (VAg/AgCl) and cathodic current density values of −8 mA/m2 and −15 mA/m2 were obtained based on the findings of this study.

Electrochemically-grown Chloride-free Cu2O nanocubes favorably electroreduce CO2 to Methane: The interplay of appropriate electrochemical protocol

Nowadays, electrochemical CO2 reduction reaction (CO2RR) to value-added products represents one of the major challenges in electrocatalysis. Copper-based nanocubes (Cu NCs) have been proposed as the front-runner's catalyst for the production of C2+ products at the industrial level. However, their selectivity (C1 vs. C2 product distribution) is rather complex depending on the dynamic structural transformations, the presence of mixed Cu+/Cu0 states, the microenvironment, and nanocatalyst-support interactions. Commonly, electrochemically-grown Cu NCs are prepared in the presence of chlorides that acts as a shaping agent. In this study, an optimized electrodeposition method for the synthesis of Cl−-free Cu2O nanocubes on a glassy carbon substrate with uniform size, shape, and loading is established. The successful preparation of chloride-free cuprous oxide nanocubes (Cu2O NCs) was confirmed with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses. We report how the electrochemical double-layer capacitance (EDLC) method for electrochemical surface area (ECSA) determination with(out) subsequent return to the open-circuit potential (OCP) conditions before electrolysis influences the CO2RR activity/selectivity. When Cu2O NCs are subjected to the EDLC method (often considered a non-invasive method) and exposed to the OCP before electrolysis, they become active for methane (CH4) formation. Moreover, the influence of the potential window width (i.e. 200 and 400 mV) in which the EDLC-ECSA is employed and its correlations with the selectivity is presented. We underline the importance of the ECSA determination method and OCP on/off state as a triggering factor for reactivity/selectivity of particular Cu2O NCs for CO2RR and further emphasize the reconstructive nature of Cu2O NCs under CO2RR relevant conditions.

High Purity Pd Nanofilm Deposition Via Cu Incorporation Control in Slrr Process

Department of Materials Science & Chemical Engineering, Hanyang University, Ansan 15588, Korea *byyoo@hanyang.ac.kr ABSTRACT The deposition of palladium has been considered in many industrial applications and in fundamental science because of the high catalytic activities. Careful control of smooth and continuous Pd film less than 1nm thickness is critical for achieving highly active catalysts. Furthermore, perspective of cost-effective view, minimum usage of Pd is essential for catalyst while showing maximum activity for catalyst due to its high cost.Electrochemical-atomic layer deposition (E-ALD), can achieve the growth of atomic level of metal film under room temperature and simple condition. E- ALD protocol proceeds using surface limited redox replacement (SLRR). SLRR involves 2 step. First, Au substrate is covered with Cu monolayer, the result of underpotential deposition of Cu (sacrificial element). Underpotential deposition (UPD) is the deposition occurs at more positive potential than equilibrium potential which the potential where deposition actually strats and UPD can limit Cu deposition by atomic layer. Second, Cu atomic layer is replaced by more noble metal (Pd) by galvanic displacement without applying potential. In one cell approach, the concentration ratio of sacrificial metal and noble metal and potential set is carefully set in order to deposit pure noble metal layer. Therefore, precise control of potential and metal concentration is important to execute successful SLRR which prevent Cu incorporation and Pd overpotential deposition upon Cu UPD formation.In this study, pure Pd nanofilm was formed on Au substrate using Cu sacrificial metal by SLRR protocol. Effort of minimizing Cu incorporation was conducted by controlling Pd ion concentration, potential , open circuit potential condition and adding additive. Pd film was characterized by XPS, AFM and open circuit potential was analyzed by potentiostat. By controlling Pd deposition condition, pure Pd film was successfully formed. KEYWORDS Palladium, one-cell, nanofilm, SLRR, Cu UPD

Interfacial Chemistry and Electrolyte Approaches for Enabling Metal Anode Batteries

Continuous solid electrolyte interphase (SEI) and dendrite growth, as well as formation of ion blocking interfaces are some of the crucial issues preventing the commercialization of batteries depending on the implementation of Li/Na/K/Mg/Ca metal anodes.[1,2] In the first part of my talk, I will focus on the chemistry of formed interfaces, including growth and ion transport control. Second part of my talk deals with bulk liquid, polymer and hybrid electrolyte molecular structure approaches for circumventing dendrite formation.Understanding of the SEI growth on alkali and alkaline earth metals in contact with liquid electrolytes under open circuit potential conditions important for shelf aging is still in its infancy. I will show that the SEI formed on Li in contact with glyme-based electrolyte grows via reaction-controlled mechanism that is rapidly substituted by the diffusion-controlled one.[3] The ionic transport and stability of the complex composite SEI material under current is highly dependent on the salt chemistry, with detrimental effects of LixSy and positive effects of the Li3N constituents. Most recent ion transport and morphological studies show that the initial SEI formed in contact with liquid electrolytes on Li, Na and Mg is nanoporous.[4,5] Based on the electrochemical impedance spectroscopy measurements in symmetric cells and related equivalent circuit models, I will discuss potential growth mechanism via SEI densification. Finally, I will present a possibility of using gas/solid synthesis for preparation of sulfide-based artificial SEIs for both liquid-based and solid-state batteries.[6]Dendrite formation on alkali and alkaline earth metal anodes is closely related to the ion concentration gradients formed near the electrodes in contact with the electrolytes. I will discuss the method to circumvent this problem by using electrolytes with high cationic transference number. In soft matter electrolytes this is possible when (i) interfacial effect enables preferential anionic adsorption in liquid/solid electrolytes,[7] (ii) the size and steric effects control the association and mobility of the anion in the liquid electrolytes,[8] (iii) ion transport proceeds through percolating amorphous clusters in polymer-in-salt electrolytes. [9]

A novel g-C3N4/In2O3/BiVO4 heterojunction photoanode for improved the photoelectrochemical cathodic protection of 304 SS stainless steel under solar light

Recently, photocathodic protection has been regarded as one of the environment-friendly techniques for metal's anti-corrosion. In this technique, n-type semiconductor photoanode produces photogenerated electrons to reparation the lost electrons from metals. Therefore, significant efforts have been made to develop materials with facile methods for improving metals photocathodic protection. Herein, g-C3N4/In2O3/BiVO4 trinary system composite was synthesized through a novel approach. The XRD, UV, and PL techniques were used to confirm the enhancement in photogenerated electrons. Furthermore, the photoelectrochemical results showed that the prepared samples increased the negativity of the 304 SS stainless steel under open circuit potential (OCP) conditions. Additionally, the potential of the 304 SS polarization showed a negative shift from − 505 to − 625 mV and − 635 mV after joined to In2O3/BiVO4 and C3N4/In2O3/BiVO4, respectively. Moreover, the presence of g-C3N4 was provided extra cathodic protection, providing polarization potential more negative during light off. That expects the insertion of this material into the offshore facilities coating to increase its lifetime and decrease corroded metals' discharge into the water bodies.

Electrochemical impedance spectroscopy characteristic of degradation process for carbon fiber/vinyl ester composites in salt water

The Electrochemical impedance spectroscopy of the T700/VE (vinyl ester) carbon fiber composite in 3.5% NaCl solution under open circuit potential (OCP) and cathodic polarization (−0.6 VSCE and −1.2 VSCE) conditions were studied, the moisture absorption was evaluated by weight gain test, and the degradation process was analyzed combined with scanning electron microscope. The T700/VE composite has very good resistance to degradation under OCP condition for long time (205 days) immersion, with about 0.38% moisture uptake and a slight decrease of low-frequency impedance (| Z|0.01 Hz). Cathodic polarization remarkably promotes the diffusion of moisture and ions in the resin matrix, the de-bonding between resin and carbon fibers, and characteristic of a porous electrode occurrence with a very quick decrease in | Z|0.01 Hz value. The variation of | Z|0.01 Hz is negatively correlated with the moisture absorption under OCP and −0.6 VSCE polarization conditions. So, | Z|0.01Hz may be used to monitor the water absorption and degradation process of the composite.