Structural study of the Cu2+-loaded copper hexacyanoferrate electrode deposited on ITO substrate

We report the structural characterization by XAFS spectroscopy at the Cu K-edge of three different CuHCF-based electrodes deposited on ITO (indium tin oxide) substrate. The electrochemical characterization confirms the occurrence of typical CuHCF films on the ITO surface. The EXAFS analysis evidences the strong multiple scattering effects in these compounds which makes the EXAFS probe effective for distances up to 5 Ǻ from the photo-absorber. The presence of Cu-N-C-Fe linear chains with a high multiplicity has allowed us to determine accurately the local environment of Cu which also includes the Fe atom. The XAFS characterization of the Cu2+-loaded CuHCF shows the best agreement with the structural model for copper hexacyanoferrate, which also features [Fe(CN)6]3- ion vacancies.