Valence- and element-dependent water oxidation behaviors: In situ X-ray diffraction, absorption and electrochemical impedance spectroscopies

Chia Shuo Hsu, Nian Tzu Suen, Ying Ya Hsu, Hsuan Yu Lin, Ching Wei Tung, Yen Fa Liao, Ting Shan Chan, Hwo Shuenn Sheu, San-Yuan Chen, Hao Ming Chen*

*Corresponding author for this work

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Metal oxides of the spinel family have shown great potential towards the oxygen evolution reaction (OER), but the fundamental OER mechanism of spinel oxides is still far from being completely understood, especially for the role of the metal ions. Owing to various coordinated sites of divalent/trivalent metals ions and surface conditions (morphology and defects), it is a great challenge to have a fair assessment of the electrocatalytic performance of spinel systems. Herein, we demonstrated a series of MFe 2 O 4 (M = Fe, Co, Ni, Zn) with a well-controlled morphology to achieve a comprehensive study of electrocatalytic activity toward OER. By utilizing several in situ analyses, we could conclude a universal rule that the activities for OER in the metal oxide systems were determined by the occurrence of a phase transformation, and this structural transformation could work well in both crystallographic sites (T d and O h sites). Additionally, the divalent metal ion significantly dominated the formation of oxyhydroxide through an epitaxial relationship, which depended on the atomic arrangement at the interface of spinel and metal oxyhydroxide, while trivalent metal ions remained unchanged as a host lattice. The metal oxyhydroxide was formed during a redox reaction rather than being formed during OER. The occurrence of the redox reaction seems to accompany a remarkable increase in resistance and capacitance might result from the structural transformation from spinel to metal oxyhydroxide. We believe that the approaching strategies and information obtained in the present study can offer a guide to designing a promising electrocatalytic system towards the oxygen evolution reaction and other fields.

Original languageEnglish
Pages (from-to)8681-8693
Number of pages13
JournalPhysical Chemistry Chemical Physics
Volume19
Issue number13
DOIs
StatePublished - 1 Jan 2017

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