Electromodified NiFe Alloys as Electrocatalysts for Water Oxidation: Mechanistic Implications of Time‐Resolved UV/Vis Tracking of Oxidation State Changes. Issue 9 (29th January 2019)

• Record Type: Journal Article
• Authors: Loos, Stefan; Zaharieva, Ivelina; Chernev, Petko; Lißner, Andreas; Dau, Holger
• Is Part Of: ChemSusChem. Volume 12:Issue 9(2019)
• Page Start: 1966
• Page End: 1976
• Publication Date: 2019-01-29
• Subjects: electrocatalysis -- NiFe oxyhydroxides -- spectroelectrochemistry -- water oxidation -- X-ray photoelectron spectroscopy; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201802737
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: Facile electromodification of metallic NiFe alloys leads to a series of NiFe oxyhydroxide surface films with excellent electrocatalytic performance in alkaline water oxidation. During cyclic voltammetry and after sudden potential jumps between noncatalytic and catalytic potentials, Ni oxidation/reduction was tracked with millisecond time resolution by a UV/Vis reflectance signal. Optimal catalysis at intermediate Ni/Fe ratios is explained by two opposing trends for increasing Fe content: a) pronounced slowdown of the Ni 2+ /Ni 3+ oxidation step and b) increased reactivity of the most oxidized catalyst state detectable at catalytic potentials. This state may involve an equilibrium between Ni 4+ ions and Ni 2+ ions with neighboring ligand holes, possibly in the form of bound peroxides. Abstract : Redox in slow motion : Facile electromodification of metallic NiFe alloys leads to a series of NiFe oxyhydroxide surface films with excellent electrocatalytic performance in alkaline water oxidation. Increasing Fe content slows down Ni 2+ /Ni 3+ oxidation state changes and enhances oxygen evolution reactivity involving an equilibrium between Ni 4+ and Ni 2+ states with ligand holes.