Electrochemical Phenomena in Complex Materials

Electrochemical modulation and modification of materials is an exciting area of research for energy applications, particularly photo-electrochemistry and electrochemical storage. On one hand, electrochemical modulation of surfaces (schematically shown in figure below) has gained a lot of attention, as it provides an alternative means to access known and unknown electronic phases with the help of the high capacity electric double layer. We have shown that this technique can be a very useful tool to understand electron transport in oxide Mott insulators. Our research effort will focus in employing similar device geometry but with more elaborate electrochemical counter electrodes to study two specific aspects of electrochemical energy conversion and storage. Firstly, we are interested in studying the electrochemistry of semiconductor (SC)/electrocatalyst (EC) couples for solar water splitting (or the related process of reduction of CO₂). Solar water splitting is a method to convert solar energy into renewable H₂ gas directly using a SC/EC system. The semiconductor absorbs the light and produces electron-hole pairs and the EC facilitates and/or enhances the water oxidation reaction at the EC/electrolyte interfaces. This research effort will focus on developing new materials and heterostructuring strategies to achieve high efficiency photoelectrochemical systems. The second problem of interest is with regards to electrochemical storage. The bottleneck for the performance enhancement for the Li-ion batteries remains the low capacity of the cathode. Even though discovery and development of new cathode materials remains an important challenge, it is also important to understand and discover new anode materials as the failure and performance degradation of the battery is directly related to the performance of the anode. This research direction will focus on understanding the intercalation and degradation mechanisms of 2D materials under electrochemical processes.

Relevant Publications:

• J. Ravichandran, C. R. Serrao, D. K. Efetov, D. Yi, Y. S. Oh, S-W. Cheong, R. Ramesh and P. Kim, “Ambipolar Transport and Magneto-resistance Crossover in a Mott Insulator, Sr₂IrO₄”, Journal of Physics: Condensed Matter 28, 505304 (2016) [IOPSelect – Articles from the last 12 months that have been chosen by our editors for their novelty, significance and potential impact on future research].

• S-Y. Zhao, G. Elbaz, D. Bediako, C. Yu, D. Efetov, Y. Guo, J. Ravichandran, K-A. Min, S. Hong, T. Taniguchi, K. Watanabe, L. Brus, X. Roy, P. Kim,”Controlled Electrochemical Intercalation of Graphene/h-BN van der Waals Heterostructures”, Nano Letters, 18(1), 460 (2018).