Oxygen reduction reaction monitored during corrosion by means of pumped-micropipette delivery/substrate collection (Pumped-MD/SC) mode of scanning electrochemical microscopy - Sorbonne Université Access content directly
Journal Articles Electrochimica Acta Year : 2023

Oxygen reduction reaction monitored during corrosion by means of pumped-micropipette delivery/substrate collection (Pumped-MD/SC) mode of scanning electrochemical microscopy

Abstract

The key improvement of the corrosion resistance of metals requires understanding and resolving the electrochemical reactions involved at the local scale. Here, we present the use of the pumped-micropipette delivery/substrate collection (Pumped-MD/SC) mode of scanning electrochemical microscopy (SECM) to monitor the oxygen reduction reaction (ORR) during corrosion of an Aluminum (Al) / Copper (Cu) galvanic coupled electrode, a model system of copper-rich aluminum alloys. In this case, the micropipette scans the substrate electrode pumping out a controlled flow of air-saturated electrolyte solution, which allows, through convective transport, to achieve high mass-transfer rates under steady-state conditions at the substrate electrode. The most relevant parameters in pumped-MD/SC mode were studied, it was demonstrated that the ORR current is linearly dependent on the injection flow rate. In contrast, the maximum ORR current was reached regardless of the tip-substrate distance (d) within the range of L (d/ micropipette radius (a)) < 15, which represents a clear advantage in comparison with other modes of SECM. It was also proved that the ORR might take place on both Cu and Al electrodes depending on the applied potential. In addition, the pumped-MD/SC mode of SECM was successfully used for imaging large dimension surfaces with both high spatial and temporal resolution, as well as high imaging contrast thanks to the high mass-transfer rate of electroactive species achieved by forced convection. Moreover, relevant information to evaluate the effect of different corrosion inhibitors in solution such as Ce2(SO4)3 and Li2CO3 on ORR was provided by individually addressing the substrate electrode in static pumped-MD/SC mode. It was demonstrated that only Ce2(SO4)3 played the role of cathodic inhibitor through the formation of a Ce3+ oxide/hydroxide precipitate on the substrate electrode during ORR, which was confirmed by SEM and EDX analysis.
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Dates and versions

hal-03934097 , version 1 (12-01-2023)

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Abdelilah Asserghine, Sophie Juillard, Julie Ducrot, Vincent Vivier, Carlos Sánchez-Sánchez. Oxygen reduction reaction monitored during corrosion by means of pumped-micropipette delivery/substrate collection (Pumped-MD/SC) mode of scanning electrochemical microscopy. Electrochimica Acta, 2023, 441, pp.141775. ⟨10.1016/j.electacta.2022.141775⟩. ⟨hal-03934097⟩
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