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This work applies electrochemical noise technique (EN) and scanning electrochemical microscopy (SECM) to investigate the initial stages of degradation of AZ31B magnesium alloy in simulated body fluid (SBF). The fluctuations in potential and current, caused by the alloy's spontaneous degradation, were analyzed in both time and frequency domains to determine the type of attack and the fractal nature of the degradation. Substrate-generation/tip-collection mode SECM mapped the hydrogen evolution activity at the Mg surface during the initial corrosion process. This electrochemical information was correlated with pH changes of the solution, Mg ion concentration, mass loss, SEM-EDS and XPS analysis. The Mg matrix dissolution was promoted by Al-Mn intermetallic particles, which acted as cathodic sites. The corrosion products film was mainly composed by Mg(OH) 2 and Ca 10 (PO 4 ) 6 (OH) 2 , and its fast formation allowed a slower degradation and H 2 evolution rates. Combining EN and SECM methods allowed the description of the early degradation processes of AZ31B in SBF as a persistent stationary process, related to fractional Gaussian noise, which was characterized by the quasi-uniform corrosion of the alloy.

Magnesium alloys have recently been considered as very promising materials for biodegradable and resorbable medical implants. Despite this work, there are very few studies that use microelectrochemical techniques for characterizing these alloys in a physiological environment. Here, the scanning electrochemical microscope (SECM) is used to map and assess the initial stages of electrochemical degradation of AZ91D magnesium alloy when exposed to simulated body fluid (SBF). The SECM feedback mode was used to monitor physical changes in the AZ91D surface, while the substrate-generation/tip-collection mode (SG/TC) was used to map the hydrogen evolution flux caused by magnesium corrosion. The results indicate dynamic electrochemical activity on the AZ91D substrate at short exposure times, indicating rapid pit nucleation and changes in hydrogen evolution intensity. In addition, SECM maps were correlated with alloy microstructure by optical and SEM-EDS images

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There is significant interest in the design of high-performance electrocatalysts for efficient electrochemical reduction of CO2 to address the pressing environmental issue and climate change. Herein, a novel copper–aluminum nanostructured catalyst is fabricated via an alloying/dealloying technique. The effect of the initial alloy’s elemental composition and subsequent dealloying, via HCl acid treatments, on the stability and activity of the catalyst for electrochemical CO2 reduction is studied. The optimized porous catalyst shows high catalytic activity for the electrochemical CO2 reduction reaction (CO2RR) with current efficiencies achieving greater than 81%. Gas and liquid product analysis confirms the formation of CO, H2, and HCOO–. Scanning electrochemical microscopy was employed to monitor the activity of the catalyst and the CO2RR products. In situ electrochemical FTIR spectroscopic studies revealed the first CO2RR intermediate was carbon-bound to the acid-treated 50:50 Cu/Al (at. %) alloy surface in a monodentate orientation. The synthetic approach reported in the present study leads to a new promising electrocatalyst with superior catalytic activity and high efficiencies for the effective electrochemical reduction of CO2 to valuable products.