Paper EH-TuE2
Electrochemistry at Well-defined Interfaces in Organic Environments

Tuesday, December 13, 2016, 6:00 pm, Room Lehua

In recent years, improvements in the fundamental understanding of electrochemical interfaces and their role in electrocatalytic processes have started to revolutionize the development of alternative energy systems for clean energy production, storage and conversion. In many respects the subject of surface electrochemistry in aqueous environments is more advanced than the corresponding understanding of interfaces in organic solvents. This is due to a long-standing difficulty associated with developing in-situ methods that are capable of characterizing interfaces at atomic-/molecular levels in organic solvents. This intrinsic disparity in understanding, however, has a tendency to mask the inherently close ties that exist between interfacial phenomena in aqueous and organic environments [1]. In this presentation, by building a bridge between these two artificially differentiated types of interfaces will allow for us to define the landscape of parameters that control the coupled roles of surface structure, chemical identity, electrostatic field, solvation and other related factors that determine the functional links between activity, selectivity and stability of any electrochemical interface. Selected example will be discussed, ranging from oxygen electrochemistry to metal deposition of Mg all the way down to intercalation processes on well-defined single crystal oxide materials. We identify the profound impact of trace levels of H₂O (<3ppm) on the kinetics of Mg deposition as well Mg intercalation in a layered V₂O₅ compound. Two types of water has been found; a “bad water”, that via the formation of MgO and Mg(OH)₂ passive films inhibits Mg deposition as well as a “good water” that helps intercalation of Mg²⁺ into V₂O₅ structures [2]. We conclude that understanding the complexity of electrochemical interfaces would open new avenues for design and deployment of alternative storage systems.

References:

1. V.R. Stamenkovic, D. Strmcnik, P. Lopes, and N.M. Markovic, Nature Materials (2016), in press.