Study of Hydride formation on Ni cathodes by coating vanadium based thin films for electrochemical applications.

Electrochemical water splitting to produce green hydrogen is a key component in our global efforts to combat climate change. Ni based electrodes are chosen for alkaline water electrolysis due to their high electrochemical activity towards hydrogen evolution reaction (HER). However, these Ni cathodes are reported to become deactivated during alkaline operation leading to higher overpotential (at constant current).  This phenomenon is attributed to deactivation of the Ni surface due to hydrogen absorption and subsequent formation of Ni-Hydride. Addition of vanadium pentoxide (V2O5) in the KOH electrolyte (8M at 70 C) has been reported to result in reactivation of the Ni surface by formation of vanadium-rich deposits on the Ni surface.

Rather than indirectly growing vanadium deposits on Ni electrodes as mentioned above, this work proposes a study of Ni hydride formation and stripping by using model thin film systems of vanadium (oxide) on nickel. Such model thin film systems offer the ability to control thickness and uniformity along with the properties of the interface. It is proposed to coat Ni surfaces with uniform thin layers of vanadium or V2O5, or alternatively, NiV alloys to use as electrodes. These layers can be compared for their ability to prevent/limit hydride formation and understand the mechanism of such processes by using electrochemical techniques. Furthermore, a coating of porous V2O5 (Vanadicone) can be considered to mimic formation of local islands V2O5 on the Ni surface. Deposition of these layers will be carried out using techniques like sputtering, atomic layer deposition, or by electrochemical methods. 
Finally, selected coatings could be applied to Ni nanomesh electrodes. These Ni nanomesh electrodes, developed at imec, have a very large volumetric area. In hydrogen evolution, a 4 µm thick nanomesh gives ~100x higher current density than planar electrodes. Combining this area enhancement with a stable performance towards hydrogen evolution, would be a great step forward in hydrogen generation technology. 

During this master thesis, performed at the imec Leuven campus, the student will acquire hands-on experience with thin film deposition using PVD and various characterization techniques such as SEM, AFM and electrochemical methods.

Type of Project: Thesis 

Master's degree: Master of Bioengineering 

Master program: Bioscience Engineering; Chemistry/Chemical Engineering; Energy; Materials Engineering; Nanoscience & Nanotechnology 

Supervisor: Philippe Vereecken (Bioscience, Nano) 

For more information or application, please contact the supervising scientists Sukhvinder Singh (Sukhvinder.Singh@imec.be) and Patrick Steegstra (Patrick.Steegstra@imec.be).