Operando X-ray absorption spectroscopy of hyperfine β-FeOOH nanorods modified with amorphous Ni(OH)2 under electrocatalytic water oxidation conditions

Abstract

Operando X-ray absorption spectroscopy was employed to study an active electrocatalyst, hyperfine β-FeOOH nanorods (∅ 3 × 15 nm) surface-modified with amorphous Ni hydroxide. The nearest neighbor structure and valence of Fe³⁺ ions did not change under water oxidation conditions, while changes in the nearest neighbor ordering of Ni²⁺ ions and a reversible transition to Ni³⁺ were observed in accordance with the electrical bias for the reaction.