Figure 10
Operando PDF analysis for the CoOx-Pi OEC, resolving the change in fine structure associated with redox state cycling between 0.5 and 1.34 V (versus NHE). A CoOx-Pi OEC was grown on an IZO/GCA WE by 60 min electrolysis at 1.34 V (versus NHE) in 0.1 M phosphate, pH 7.0, and 0.5 mM Co(NO3)2·6H2O. Subsequently, HEXS and PDF patterns were measured as a function of applied potential that was cycled between 0.5 V, 1.0 V and 1.5 V (versus NHE). The figure compares PDF patterns measured at 0.5 V and 1.0 V in the blue and red line traces, respectively. The peaks labeled a through to g correspond to atom-pair distances that are characteristic of the cobaltate domain structure (Du et al., 2012; Kwon et al., 2015). For example, the peak a is associated with the first-shell Co–O ligand distances, and peak b corresponds to the Co–Co distance across the di-μ-oxo bond. Illustrative structures are inserted next to each of these peaks. The cobalt and oxygen atoms are colored blue and red, respectively. |