Simulation of interfacial pH changes during hydrogen evolution reaction

This work investigates the possibility of interfacial pH changes during a hydrogen evolution reaction using a finite elements simulation approach. This reaction is a common side step observed in many electrochemical systems, such as electrodeposition or corrosion. To develop a general approach, different mechanisms, i.e., Volmer/Tafel and Volmer/Heyrovsky, were investigated. It is observed that for V-H mechanism the interfacial pH change increases 4.2 pH units for those cases where the bulk pH is 5.0. Therefore, in this case, the instant pH at the interface become alkaline, although the bulk is still acidic, which could justify parallel reactions such as metal hydroxide formation in metal electrodeposition. Besides, the interfacial pH changes and the corresponding pH profiles were calculated under several experimental conditions including the composition of the metallic electrode, the bulk solution pH and the total buffer concentration UHAI + [Al-]. (C) 2015 Elsevier B.V. All rights reserved.