Scanning electrochemical microscopy (SECM) is widely used to measure local reactivity of corroding surfaces. A major criticism using SECM in feedback mode for corrosion studies the requirement an external redox mediator (RM) as it could react with metal and affect Nernst potential at metal-solution interface. Consequently, becomes challenging differentiate interference caused by RM from metal. Herein, a multiscale approach presented investigate effect choice on substrate. Two common RMs,...

Scanning electrochemical microscopy (SECM) is a popular tool to study corrosion with high spatial resolution. The feedback mode of SECM involves the use an added redox mediator in solution probe local surface kinetics. Depending on mediator's oxidation state and formal potential, as well corroding metal's electroactive species can potentially polarize substrate alter behavior at macro and/or microscale. Therefore, choice material dependent. This explored methyl viologen (MV) ideal for...

This work deals with the degradation of AZ31 and AZ91 magnesium alloys when they are exposed to three types physiological media for seven days at 37 °C: Ringer's, Hanks', simulated body fluid (SBF) solutions. A combination immersions tests surface characterisation methods were employed evaluate attack on surface, stability formed corrosion product layers each alloy/electrolyte system. Measurements Mg-ion released into electrolytes also carried out in order be correlated alloys....

There is significant interest in the design of high-performance electrocatalysts for efficient electrochemical reduction CO2 to address pressing environmental issue and climate change. Herein, a novel copper–aluminum nanostructured catalyst fabricated via an alloying/dealloying technique. The effect initial alloy's elemental composition subsequent dealloying, HCl acid treatments, on stability activity studied. optimized porous shows high catalytic reaction (CO2RR) with current efficiencies...

This work applies electrochemical noise technique (EN) and scanning microscopy (SECM) to investigate the initial stages of degradation AZ31B magnesium alloy in simulated body fluid (SBF). The fluctuations potential current, caused by alloy's spontaneous degradation, were analyzed both time frequency domains determine type attack fractal nature degradation. Substrate-generation/tip-collection mode SECM mapped hydrogen evolution activity at Mg surface during corrosion process. information was...

Scanning electrochemical microscopy (SECM) is a technique for imaging reactions at surface. The interaction between occurring the sample and scanning electrode tip quite complicated requires computer modeling to obtain quantitative information from SECM images. Often, existing models must be modified, or new model created scratch fit kinetic parameters different reactive features. This work presents method that can simulate image of feature any shape on flat surface which coupled program...

A deep understanding of the properties semiconductor films at micro-/nanoscale level is fundamental toward designing effective photoelectrocatalysts. Here, we integrated spatially resolved optical spectroscopy (SR-OS) with scanning photoelectrochemical microscopy (SPECM) to collect UV/vis spectra and quantify photocurrents localized sites on a nanostructured BiVO4 thin film. Direct measurement absorbance allowed for determination band gap energy each location. Absorbance photocurrent maps...

This work presents a simple method to functionalise the surface of AZ31 magnesium alloy by applying duplex MgF2/chitosan coating, which improves its corrosion resistance and provides it with some antibacterial performance. First, effect three chitosan solutions different concentrations on growth bacteria Klebsiella pneumoniae in nutritive medium (TSB) was evaluated absorbance kinetics experiments, where solution at 2% (m/V) selected for coating preparation. Before application, substrate...

This work presents a new methodology to estimate the surface area of working electrode during scanning electrochemical cell microscopy (SECCM) in situ by utilizing retraction curves. In this approach, current is measured as function pipet displacement z-direction. When drops zero, it indicative droplet detachment from surface, allowing for estimation contact diameter based on displacement. enables real-time estimations areas wetted at each point measurement, rather than performing...

Scanning electrochemical microscopy (SECM) is a powerful technique for imaging the reactivity of surface. Unfortunately, SECM images are mainly used qualitatively. Kinetics reactions at surface almost exclusively obtained from microelectrode current as it approaches surface, called an approach curve. The curve method excellent when reaction has same kinetics everywhere, but was not designed to fit finite-sized reactive features. We propose extracting kinetics, feature area, and...

En el presente trabajo se ha investigado efecto de los elementos aleantes Zn (0,95% en masa) y Ca (0,15% mecanismo degradación del Mg. Las superficies Mg puro la aleación Mg-Zn-Ca han sido caracterizadas durante su exposición a solución fisiológica Hanks (a 37 °C) hasta siete días, utilizando las técnicas SEM-EDS XPS. La capa formada superficie contiene Ca10(PO4)6(OH)2, que puede mejorar compatibilidad ósea. partículas intermetálicas compuestas fase Mg2Ca, así como presencia Zn, promovido...

Magnesium alloys have been proposed as suitable biomaterials for resorbable implant applications. Although a substantial amount of research has performed on the use Mg biomedical applications, there are few studies employing micro-electrochemical techniques characterizing these materials in physiological environments. The unique capabilities scanning electrochemical microscope (SECM) make this powerful tool situ study localized corrosion fluids. work presented will assess initial stages...

En el presente trabajo se ha aplicado una combinación de pruebas inmersión, técni­cas análisis superficie y métodos electroquímicos para caracterizar proceso degradación la aleación magnesio AZ31 cuando sido expuesta a saliva artificial durante 28 días. La fue evaluada en dos condiciones: simple con capa MgF2. Esta conversión formó sumergiendo ácido fluorhídrico (HF). Las imágenes SEM revelaron diferencias ataque corrosión las condiciones superficie, específicamente vecindad partículas...

The strength of scanning electrochemical microscopy measurements (SECM) is its ability to give insights into the kinetics an underlying surface. Up now there was no established way extract from SECM image. Our study fills this gap by proposing a method that fits active area and reactive sites images using Levenberg-Marquardt algorithm finite element simulations. Currently, reactions at surface are quantified through performing approach curves: measuring current as microelectrode approaches...

Corrosion is one of the most destructive on environment and also our safety. Not only does microstructure influence severity corrosion, but many other chemical mechanical factors such as fatigue. For this reason, ability to evaluate further predict localized corrosion materials subjected stress has been a growing interest in an attempt foresee fatigue-corrosion damage before escalating into material failure, years later. A quantitative qualitative investigation was conducted assess effect...