Local structure of chromium incorporated into electrodeposited nickel hydroxide films

We have utilized X-ray Absorption Fine Structure (XAFS) spectroscopy to investigate the local structure of Cr (III) and Cr (VI) ions incorporated into alpha-Ni(OH)(2) films. The films were prepared by cathodic co-deposition of Cr and Ni at a constant current from aqueous solutions of nickel nitrate, chromium nitrate and potassium chromate. XAFS measurements show that in films formed from 0.1 M Ni(NO3)(2) + 0.0005 M Cr(NO3)(3), Cr (III) is incorporated into the Ni lattice sites of alpha-Ni(OH)(2). In contrast, co-deposition from a 0.1 M Ni(NO3)(2) + 0.001 M K2CrO4 solution results in Cr (VI) occupying the interlamellar sites of the brucite structure.