SECM

Scanning Electrochemical Microscopy (SECM) 


The Leonard group utilizes scanning electrochemical microscopy (SECM) in the development and characterization of electrocatalysts. Scanning electrochemical microscopy (SECM) is a “non-contact” scanning probe technique capable of
providing chemical and/or topographic information about surfaces immersed in a solution. It is a powerful in situ and
operando tool for obtaining insights into electrocatalytic rates and mechanisms. Using SECM, one is able to very accurately determine the kinetics of electrochemical reactions, as well as mechanistic information can be obtained by the investigation of reaction intermediates.


SECM Tip Schematic




Schematic comparing (A) the traditional tip generation/ substrate collection (TG/SC) mode of SECM to (B) the multireactional TG/SC mode of SECM. In the multireactional TG/SC mode, two reactions occur on the tip electrode while only one product is collected on the substrate electrode. This allows for separation of simultaneous reactions occurring on the tip electrode. [Leonard, K. C.; Bard, A. J. J. Am. Chem. Soc. 2013, 135, 15890–15896]


COMSOL Simulations




[Jantz. D.T. and Leonard, K.C. “Characterizing Electrocatalysts with Scanning Electrochemical Microscopy.” Industrial & Engineering Chemistry Research Vol. 57, Issue 22, pp. 7431-7440 (2018).]




Example of Chemical Reactivity Maps Obtained Via SECM






SECM positive feedback image of the letters “KU” printed in gold on a glass slide using a 200 mm Pt tip electrode at +0.4 V vs Ag/AgCl in 0.5 mM FcMeOH. (A) Positive feedback image before the automated substrate tilt algorithm was performed. (B) Positive feedback image after the automated substrate tilt algorithm was performed.  [Barforoush, J.M.; McDonald, T.D.; Desai, T.; Widrig, D.; Bayer, C.; Brown, M. K.; Cumming, L.C. and Leonard, K.C. “Intelligent Scanning Electrochemical Microscopy Tip and Substrate Control Utilizing Fuzzy Logic.” Electrochimica Acta Vol. 190, pp.713-719 (2016)]





[Kim, J.; Renault, C.; Nioradze, N. Arroyo-Curras, N.; Leonard, K.C. and Bard, A.J. “Electrocatalytic Activity of Individual Pt Nanoparticles Studied by Nanoscale Scanning Electrochemical Microscopy.”  Journal of The American Chemical Society Vol. 138, Issue 27, pp. 8560-8568 (2016)]


Examples of Surface-Interrogation SECM




[Barforoush, J.M.; Jantz. D.T.; Seuferling, T.E.; Song, K.R.; Cummings, L.C. and Leonard, K.C. “Microwave-Assisted Synthesis of a Nanoamorphous (Ni0.8,Fe0.2) oxide oxygen-evolving electrocatalyst containing only ‘fast’ sites.” Journal of Materials Chemistry A Vol. 5, Issue 23, pp. 11661-11670 (2017).]


Example of Multi-Reactional SECM




[Jantz. D.T. and Leonard, K.C. “Characterizing Electrocatalysts with Scanning Electrochemical Microscopy.” Industrial & Engineering Chemistry Research Vol. 57, Issue 22, pp. 7431-7440 (2018).]