Alpha‐Nickel Hydroxide Coating of Metallic Nickel for Enhanced Alkaline Hydrogen Evolution
Song Xue, Yunchang Liang, Shujin Hou, Yajing Zhang, Heqing Jiang
Abstract
Abstract In this work, alkaline hydrogen evolution reaction (HER) processes of three typical nickel‐based electrocatalysts [i. e., Ni, α‐Ni(OH) 2 , and β‐Ni(OH) 2 ] were investigated to probe critical factors that determine the activity and durability. The HER activity trend was observed as Ni≫α‐Ni(OH) 2 >β‐Ni(OH) 2 , likely attributed to a synergy between metallic Ni and Ni(OH) 2 components on the Ni surface and fast water dissociation kinetics on the α‐Ni(OH) 2 surface. With the HER proceeding, the metallic Ni surface, however, gradually became α‐Ni(OH) 2 , and α‐Ni(OH) 2 surface ultimately transformed into β‐phase, leading to a dramatic activity decrease of Ni electrodes. Therefore, Ni electrodes were coated with α‐Ni(OH) 2 nanosheets to slow down the nickel hydroxylation and optimize the surface ratio of Ni(OH) 2 to metallic Ni. This simple coating procedure enhanced both activity and durability of Ni electrocatalysts.