Y. Yu, K. Zhang, D. Kwabena Bediako
George Mason University,
Keywords: electrochemistry, SECCM, STM, 2D material, moiré
Summary:Tailoring electron transfer dynamics across solid–liquid interfaces is fundamental to the interconversion of electrical and chemical energy. Stacking atomically thin layers with a small misorientation to produce moiré superlattices enables the controlled engineering of electronic band structures. In this presentation, I will describe our approach to investigating the twist-angle dependence of electrochemical activity at twisted bilayer graphene electrodes. Scanning tunneling microscopy (STM) was employed to visualize the constructed moiré patterns to determine the twist angle and uniaxial heterostrain. Scanning electrochemical cell microscopy (SECCM) allowed us to obtain nanoscale electrochemical measurements exclusively at the basal plane of the twisted bilayer graphene. A strong twist-angle dependence of heterogeneous charge transfer kinetics with the greatest enhancement near the “magic angle” was observed. This effect is driven by the angle-dependent moiré-derived flat bands that modulate electron transfer processes with the solution-phase redox couple. Combined experimental and computational analysis reveals that the variation in electrochemical activity is controlled by a structural relaxation of the moiré superlattice and localized enhancement at specific stacking domains. This work highlights the importance of correlative electrochemical multimicroscopy in resolving the structure–activity relationships of nanoscale electrode materials. Reference: Y. Yu, K. Zhang, H. Parks, M. Babar, S. Carr, I. Craig, M. Van Winkle, A. Lyssenko, T. Taniguchi, K. Watanabe, V. Viswanathan, D. K. Bediako, Tunable Electrochemistry with Moiré Flat Bands and Topological Defects at Twisted Bilayer Graphene. Nat. Chem. 2022, 14, 267–273.