Hydrothermal synthesis of polydopamine-functionalized cobalt-doped lanthanum nickelate perovskite nanorods for efficient water oxidation in alkaline solution

Perovskite oxides have attracted great attention recently for their low cost and high intrinsic activity in the electrochemical oxygen evolution reaction (OER). In this work, we synthesized highly efficient OER electrocatalysts in alkaline solution by carbonization of polydopamine (PDA)-functionalized cobalt-doped lanthanum nickelate perovskite nanorod (La₅Ni₃Co₂) complexes. The calcination temperature and molar ratio for La, Ni, and Co were optimized. The as-prepared complex with a molar ratio of 5 : 3 : 2 (La : Ni : Co) and a calcination temperature of 500 °C displayed enhanced OER activity and excellent durability. In 1.0 M KOH, the overpotential of the as-prepared catalyst at a current density of 10 mA cm^-2 was 0.360 V, which is comparable to those of noble metal-based materials or perovskite-based materials. The Tafel slope is 48.1 mV dec^-1, which is smaller than those of prepared composites. The satisfactory oxygen evolution activity could be attributed to the increased Co₃O₄, O₂^2-/O^-, pyridine N, and quaternary N species after calcination treatment, and the improved amount of Ni³⁺ during the OER process, as well as the high surface area and electrochemical surface area.