Structured Electrodes Induce Local pH as a Primary Determinant of CO2 Reduction Selectivity
Document Type
Journal Article
Role
Author
Published In
Journal of the American Chemical Society
Publication Date
4-30-2026
Abstract
Highly structured electrodes permit high operating currents to be achieved as well as enhanced selectivity, especially for the carbon dioxide reduction (CDR) reaction. An understanding of the origins of CDR selectivity is complicated by the intricate internal structure of high surface area electrodes, which may modify the microenvironment in which catalysis occurs. We report here enhanced faradaic efficiency of the reduction of CO2 to CO (FE(CO)) on photolithographically fabricated Au microwire (MW) electrodes as compared with their planar counterpart. We demonstrate that this selectivity arises from the local pH gradient at the electrode–solution interface, as a result of the electrode microstructure. By employing confocal microscopy with a ratiometric pH sensor, we can construct in situ maps of the local pH at the electrode–solution interface. When normalized for local pH, the same dependence of FE(CO) is observed for the fabricated MW and planar electrodes, and the selectivity is a direct result of the HCO3–/CO32– equilibrium.
Keywords
electrodes, inorganic carbon compounds, oxides, redox reactions, selectivity
Suggested Citation
Zhu, M., Wang, Yiming (Chemistry), et al. "Structured Electrodes Induce Local pH as a Primary Determinant of CO2 Reduction Selectivity." Journal of the American Chemical Society. Available: https://doi.org/10.1021/jacs.5c22508
