Insight into the Anticorrosion Behaviors of Phase-Transformed Cobalt Hydroxides for Long-Term Electrocatalytic Water Oxidation in Saline Electrolytes

Unraveling the reconstruction of precatalysts and understanding the underlying mechanisms are crucial for the targeted design of efficient electrocatalysts. Here, a precatalyst cobalt hydroxide is fabricated to enable electrocatalytic oxidations in alkaline saline water for sustainable hydrogen production. This precatalyst undergoes distinct phase transformation routes to γ-CoOOH and β-CoOOH. γ-CoOOH with rich Lewis acid sites is considered the key component for constructing repelling layers, thereby hindering the arrival of corrosive chlorides. Conversely, the further transformed β-CoOOH fails to resist the corrosion and thus results in the etching of the nickel indicator. A supposed catalytic mechanism is presented, supported by both ex and in situ experimental studies as well as computational calculations.