Self-supported Reevesite Ni-Fe Layered Double Hydroxide Nanosheet Arrays for Efficient Water Oxidation

Rational design of high efficient and low cost oxygen evolution reaction (OER) electrodes is critical for electrochemical water splitting. Herein, we report Reevesite Ni−Fe layered double hydroxide (NiFe-(CO₃ ²⁻)-LDH) nanosheet arrays as novel OER catalysts in alkaline electrolyte. These self-supported nanosheet arrays with a composition of Ni₆Fe₂(CO₃)(OH)₁₆ ⋅ 4H₂O on Ni foam (NF) were synthesized by a one-pot hydrothermal method, in which NF served as both the conductive substrate and Ni source. The morphology and OER activity can be tuned by iron concentration. In 1 M KOH, the optimized NiFe-(CO₃ ²⁻)-LDH catalyst only required overpotentials of 228 and 264 mV to deliver current densities of 10 and 100 mA cm⁻², respectively, with a small Tafel slope of 37 mV dec⁻¹. Remarkably, this catalyst also showed outstanding durability by long-term operation for 20 h with 96 % retention. Our work provides attractive cost-effective 3D catalysts for efficient and robust water oxidation at alkaline media.