Dischargeable nickel matrix charges iron species for oxygen evolution electrocatalysis. (1st August 2021)

• Record Type: Journal Article
• Authors: Kang, Sinwoo; Ham, Kahyun; Lim, Hyung-Kyu; Lee, Jaeyoung
• Is Part Of: Electrochimica acta. Volume 386(2021)
• Publication Date: 2021-08-01
• Subjects: Oxygen evolution reaction catalysis -- Nickel-iron (oxy)hydroxide -- Operando X-ray absorption spectroscopy -- Ultraviolet photoelectron spectroscopy -- Work function; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.138401
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: MOx Hy ( M = Ni, Fe, and NiFe) film electrocatalyst fabricated on carbon substrate. NiFeOx Hy film exhibits excellent alkaline OER activity. Operando XAS reveals the highly oxidized Fe which is active site in NiFeOx Hy . UPS confirms the electron transferring effect from FeOx Hy to NiOx Hy . Abstract: Nickel-iron (oxy)hydroxide (NiFeOx Hy ) is a state-of-the-art non-precious electrocatalyst for oxygen evolution reaction (OER) in alkaline media. However, the origin of the synergy between Ni and Fe remains unclear. Here, operando X-ray absorption and ultraviolet photoelectron spectroscopy were used to prove the charging-discharging behavior of Ni and Fe when they are adjacent. Fe oxidation and Ni reduction were simultaneously observed during electrocatalytic OER in NiFeOx Hy compared to unary metal (oxy)hydroxide. The higher Fermi level of FeOx Hy compared to NiOx Hy enables charge transfer from Fe to Ni domain near the boundaries. From the experimental results, the combination of Ni and Fe results in superior oxygen-evolving activity by exposing high valent Fe coupled with a dischargeable Ni matrix. Graphical abstract: Image, graphical abstract