Boosting the Stability of Oxygen Vacancies in α-Co(OH)2 Nanosheets with Coordination Polyhedrons as Rivets for High-Performance Alkaline Hydrogen Evolution Electrocatalyst

The strong alkaline electrolytes are utilized in various key electrochemical applications and the severe corrosion by hydroxyl ions endows the development of high-performance electrode materials with a great challenge. Here, an effective strategy is demonstrated to stabilize alpha-Co(OH)(2) under harsh alkaline electrochemical condition by coordination polyhedron pinning (MoO42-, WO42-) on the surface for hydrogen evolution reaction (HER). The addition of MoO42- in 1 M KOH can inhibit the attack of hydroxyl ions on oxygen vacan- cies in alpha-Co(OH)(2), and simultaneously modulate the electronic structure of active sites for HER. The theoretical calculations and experimental results reveal that MoO42- can be riveted on the surface of alpha-Co(OH)(2) to greatly stabilize oxygen vacancies and inhibit the formation of soluble ions of Co(OH)(3)(-). The resultant active sites exhibit reduced maximum energy barriers for the optimized alkaline HER. Additionally, MoO42- near the interface between alpha-Co(OH)(2) and electrolyte can alleviate the accumulation of hydroxyl ions on alpha-Co(OH)(2) due to the electrostatic repulsion, improving the stability toward HER. This work offers insight into the role of coordination polyhedron ions in regulating and enhancing the stability of alpha-Co(OH)(2) for various potential electrochemical applications in alkaline electrolyte.

Automated summary

This study demonstrates an effective strategy to stabilize alpha-Co(OH)(2) under harsh alkaline electrochemical conditions by using MoO42- ions to stabilize oxygen vacancies and improve the stability and efficiency of hydrogen evolution reaction (HER).