Single entity electrochemistry
Optical imaging of single particle electrochemistry
Our lab uses a variety of optical imaging techniques, including surface-enhanced Raman scattering, electrogenerated chemiluminescence, dark field scattering, and fluorescence microscopy to monitor electrochemical processes involving single nanoparticles. Optical techniques offer the advantages of tracking many particles in parallel during an electrochemical experiment and revealing heterogeneity in electrochemical processes (including inactive particles, which are hidden in a traditional electrochemical experiment).
The role of the supporting substrate (ITO sucks)
To perform single entity electrochemistry experiments, we need substrates that are transparent, conductive, and compatible with our high numerical aperture objectives. The most common substrate is indium tin oxide (ITO) coated on microscope coverslips. Unfortunately, ITO introduces significant heterogeneity in our experiments. We are working on developing new substrates for single entity electrochemistry that overcome the challenges of ITO.
Related publications
L. Zhang, O.J. Wahab, A.A. Jallow, Z.J. O’Dell, T. Pungsrisai, S. Sridhar, K.L. Vernon, K.A. Willets, L.A. Baker
Anal. Chem. 96, 8036 (2024)
N.Y. Molina, T. Pungsrisai, Z.J. O’Dell, B. Paranzino, K.A. Willets
ChemElectroChem. 9, e202200245 (2022)
V. Sundaresan, A.R. Cutri, J. Metro, C. Madukoma, J.D. Shrout, A.J. Hoffman, K.A. Willets, P.W. Bohn
Electrochem. Sci. Adv. 00, e2100094 (2021)
V. Sundaresan, J.W. Monaghan, K.A. Willets
Invited contribution to a special themed issue on Single Entity Electrochemistry. ChemElectroChem. 5, 3052 (2018)
V. Sundaresan, J.W. Monaghan, K.A. Willets
J. Phys. Chem. C. 122, 3138 (2018). ACS Editors’ Choice.
Using ultramicroelectrodes (UMEs) to probe plasmonic processes
UMEs are disk electrodes that are made from wires that are encapsulated in a glass capillary and then laser heated and pulled to generate electrodes with sub-micron diameters. By suspending UMEs above plasmonic samples mounted on an optical microscope, we can measure currents generated from electrochemical reactions occurring at the nanoparticle surface and determine how laser excitation impacts the generation of hot carriers and heat.
Related publications
Y. Yu, K. Wijesekara, X.X. Xi, K.A. Willets
ACS Nano. 13, 3629 (2019)
Y. Yu, V. Sundaresan, K.A. Willets
J. Phys. Chem. C. 122, 5040 (2018)
Y. Yu, J.D. Williams, K.A. Willets
Faraday Discussions. 210, 29 (2018)