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Imaging Water-Splitting Electrocatalysts with pH-Sensing Confocal Fluorescence Microscopy

Leenheer, Andrew J. and Atwater, Harry A. (2012) Imaging Water-Splitting Electrocatalysts with pH-Sensing Confocal Fluorescence Microscopy. Journal of the Electrochemical Society, 159 (9). H752-H757. ISSN 0013-4651. doi:10.1149/2.022209jes.

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Hydrogen generation by water electrolysis is promising for energy storage, and imaging the reaction dynamics near a H_2-evolving electrode can provide valuable insights. We utilized laser-scanning confocal fluorescence microscopy to map the product/reactant concentration at a H_2-evolving electrode at micron-scale resolution which identifies areas with fast reaction kinetics. Small concentrations of a pH indicator dye added to the aqueous electrolyte enables ratiometric fluorescence sensing for quantitative pH detection over the range pH 5.3-7.5 and minimally perturbs the local environment. To overcome diffusion limitations, a miniature flow cell was utilized in the microscope to achieve micron-scale resolution in steady state while applying galvanostatic current. We demonstrated the technique using F:SnO_2-coated glass with varied metal catalyst patterns and compositions resulting in clear images of increased pH near areas of high water-reducing activity. Simulations of the pH profiles near the electrolyte-patterned catalyst interface were also performed using the COMSOL finite-element software package to solve the convection/diffusion equations, and the calculation results agreed well with the experimentally-observed fluorescence profiles. Flow cell fluoresecence microscopy shows promise in imaging comparative catalyst activity as well as three-dimensional product/reactant profiles in complex electrode architectures.

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Atwater, Harry A.0000-0001-9435-0201
Additional Information:© 2012 The Electrochemical Society. Manuscript submitted April 23, 2012; revised manuscript received June 19, 2012. Published August 14, 2012. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. We thank V. Ferry and J. McKone for helpful discussions. References
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Department of Energy (DOE)DE-SC0004993
Issue or Number:9
Record Number:CaltechAUTHORS:20121106-100653685
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Official Citation:Andrew J. Leenheer and Harry A. Atwater Imaging Water-Splitting Electrocatalysts with pH-Sensing Confocal Fluorescence Microscopy J. Electrochem. Soc. 2012 159(9): H752-H757; doi:10.1149/2.022209jes
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35296
Deposited By: Tony Diaz
Deposited On:12 Nov 2012 19:05
Last Modified:09 Nov 2021 23:14

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