Codecoration of Phosphate and Iron for Improving Oxygen Evolution Reaction of Layered Ni(OH)₂/NiOOH

Hydrogen production through electrochemical water splitting (EWS) presents a viable solution for addressing the fossil energy crisis. However, the commercial viability of this approach is impeded by the sluggish kinetics of the oxygen evolution reaction (OER). It is urgently needed to develop efficient, stable, and cost-effective OER electrocatalysts. Herein, we comprehensively design and investigate a phosphate ion and Fe³⁺ codecorating Ni(OH)₂/NiOOH electrocatalyst (Pi-Fe:NiOH) for OER. This codecoration induces multiple synergistic effects, which include an increase in the interlayer water content for the internal OER, altering the OER mechanism, facilitating proton transport across the layers, and improving the stability of Pi-Fe:NiOH. Consequently, Pi-Fe:NiOH exhibits a high OER activity with overpotentials of 118 ± 1 and 222 ± 4 mV at current densities of 10 and 100 mA cm^–2, respectively. More impressively, it maintains stable operation at a high current density of around 300 mA cm^–2 for at least 500 h, much better than the Ni(OH)₂/NiOOH electrocatalyst (NiOH) for less than 6 h at a current density below 200 mA cm^–2. These findings offer insights for the design of anion–cation codoped hydroxide eletrocatalysts, paving a way for the development of efficient and stable OER electrocatalysts.