TY - JOUR
T1 - In situ Ru K-edge X-ray absorption fine structure studies of electroprecipitated ruthenium dioxide films with relevance to supercapacitor applications
AU - Mo, Yibo
AU - Antonio, Mark R.
AU - Scherson, Daniel Alberto
PY - 2000/10/26
Y1 - 2000/10/26
N2 - Modifications in electronic and structural aspects of RuO2 films electroprecipitated onto Au electrodes induced by changes in the applied potential have been examined in situ in aqueous 0.50 M H2SO4 by Ru K-edge X-ray absorption spectroscopy (XAS). The Fourier transform of the k3-weighted extended X-ray absorption fine structure (EXAFS), k3χ(k), for the film polarized at +1.20V vs RHE is characterized by two shells attributed to Ru-O and Ru-Ru interactions with average distances of 1.94(1) and 3.12(2) Å, respectively, in agreement with results obtained ex situ for Ru4+ in hydrous RuO2 by other groups. In contrast, films in the reduced state, i.e., +0.40 V vs RHE, yielded only a single shell ascribed to a Ru-O interaction at 2.02(1) Å with no evidence for a distant Ru-Ru shell. The long Ru-O distance is in agreement with that reported earlier for the hydrous Ru3+ ion [Ru-(OH2)6]3+ in the solid state. Moreover, the difference between the average Ru-O bond lengths for the reduced and oxidized films is consistent with the difference in the ionic radii of Ru3+ and Ru4+. On this basis it has been suggested that films in the reduced state contain Ru3+ sites, consistent with the electrochemical results, in a phase with apparently less order beyond the Ru-O coordination sphere than for hydrous RuO2.
AB - Modifications in electronic and structural aspects of RuO2 films electroprecipitated onto Au electrodes induced by changes in the applied potential have been examined in situ in aqueous 0.50 M H2SO4 by Ru K-edge X-ray absorption spectroscopy (XAS). The Fourier transform of the k3-weighted extended X-ray absorption fine structure (EXAFS), k3χ(k), for the film polarized at +1.20V vs RHE is characterized by two shells attributed to Ru-O and Ru-Ru interactions with average distances of 1.94(1) and 3.12(2) Å, respectively, in agreement with results obtained ex situ for Ru4+ in hydrous RuO2 by other groups. In contrast, films in the reduced state, i.e., +0.40 V vs RHE, yielded only a single shell ascribed to a Ru-O interaction at 2.02(1) Å with no evidence for a distant Ru-Ru shell. The long Ru-O distance is in agreement with that reported earlier for the hydrous Ru3+ ion [Ru-(OH2)6]3+ in the solid state. Moreover, the difference between the average Ru-O bond lengths for the reduced and oxidized films is consistent with the difference in the ionic radii of Ru3+ and Ru4+. On this basis it has been suggested that films in the reduced state contain Ru3+ sites, consistent with the electrochemical results, in a phase with apparently less order beyond the Ru-O coordination sphere than for hydrous RuO2.
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M3 - Article
AN - SCOPUS:0034298186
SN - 1520-6106
VL - 104
SP - 9777
EP - 9779
JO - Journal of Physical Chemistry B Materials
JF - Journal of Physical Chemistry B Materials
IS - 42
ER -