Intrinsic Electrocatalytic Activity for Oxygen Evolution of Crystalline 3d-Transition Metal Layered Double Hydroxides.

Layered double hydroxides (LDHs) are among the most active and studied catalysts for the oxygen evolution reaction (OER) in alkaline electrolytes. However, previous works either focused on a small number of LDHs, applied synthetic routes with limited structural control, or used non-intrinsic activity metrics. This hampered the construction of consistent structure-activity-relations. Herein, by employing new individually developed synthesis strategies with atomic structural control, we obtained a broad series of crystalline α-M A (II)M B (III) LDH and β-M A (OH) 2 electrocatalysts (M A = Ni, Co, and M B = Co, Fe, Mn). We further derived their intrinsic activity through electrochemical active surface area normalization, which revealed the trend: NiFe LDH, CoFe LDH, Fe-free Co-containing catalysts, and Fe-Co-free Ni-based catalysts. Our theoretical reactivity modelling unraveled that the intrinsic activity trend originated from the dual-metal-site nature of the reaction centers, which lead to compound-dependent synergies, and diverse scaling relationships that may be used to design catalysts with improved performance.