Reversible adapting layer produces robust single-crystal electrocatalyst for oxygen evolution.

Ching-Wei Tung,Yen-Ping Shen,Ying-Ya Hsu,Hwo-Shuenn Sheu,Hao Ming Chen,Yixin Zheng,Yuan-Chung Cheng,Ting-Shan Chan

doi:10.1038/ncomms9106

Abstract

Electrochemically converting water into oxygen/hydrogen gas is ideal for high-density renewable energy storage in which robust electrocatalysts for efficient oxygen evolution play crucial roles. To date, however, electrocatalysts with long-term stability have remained elusive. Here we report that single-crystal Co3O4 nanocube underlay with a thin CoO layer results in a high-performance and high-stability electrocatalyst in oxygen evolution reaction. An in situ X-ray diffraction method is developed to observe a strong correlation between the initialization of the oxygen evolution and the formation of active metal oxyhydroxide phase. The lattice of skin layer adapts to the structure of the active phase, which enables a reversible facile structural change that facilitates the chemical reactions without breaking the scaffold of the electrocatalysts. The single-crystal nanocube electrode exhibits stable, continuous oxygen evolution for >1,000 h. This robust stability is attributed to the complementary nature of defect-free single-crystal electrocatalyst and the reversible adapting layer.

Highlights

Converting water into oxygen/hydrogen gas is ideal for high-density renewable energy storage in which robust electrocatalysts for efficient oxygen evolution play crucial roles
We evaluated the electrochemical activity of the Co3O4@cobalt oxide (CoO) SCs during the oxygen evolution reaction (OER) in alkaline and neutral conditions while IrO2 (Supplementary Fig. 5) and RuO2 (Supplementary Fig. 6) catalysts were tested as references (Fig. 3a)
To further test the long-term stability, we subjected it to a continual potential cycling between 1.0 and 2.0 V and used the IrO2 and RuO2 catalysts as controls in O2-saturated 0.5 M KOH while all measurements were performed using rotating disk electrode (RDE) voltammetry upon a glassy carbon (GC) disk in the desired electrolyte

Summary

Introduction

Converting water into oxygen/hydrogen gas is ideal for high-density renewable energy storage in which robust electrocatalysts for efficient oxygen evolution play crucial roles. To shed light on such complex surface reactions, we need a tool that allows in situ observation of the active phase of metal centres under anodization and a novel strategy to protect electrocatalysts under such harsh conditions in order to achieve reliable catalysts for OER.

Results

Conclusion