La-Doped LaFeCoOOH Bifunctional Materials for Oxygen Evolution Reaction and Supercapacitors

Developing efficient multifunctional materials for the oxygen evolution reaction (OER) and supercapacitors has become essential for storing and converting energy. Taking advantage of the structural flexibility of metal–organic frameworks (MOFs), bifunctional electrochemical nanomaterial LaFeCoOOH with high performance is successfully synthesized by doping rare earth La atoms in transition metals. La doping modifies the coordination environment of active sites and material morphology, modulates the energy structure, improves material conductivity, and optimizes the adsorption and desorption performance of oxygen intermediates. LaFeCoOOH demonstrates exceptional electrocatalytic activity for OER, achieving a remarkably low overpotential of 177 mV at 10 mA cm⁻² current density in 1 m KOH alkaline electrolyte. The material exhibits outstanding operational stability, maintaining consistent performance for over 1000 h at an elevated current density of 100 mA cm⁻² under identical alkaline conditions. Furthermore, LaFeCoOOH electrode displays superior electrochemical energy storage capabilities, demonstrating an impressive specific capacitance of 3508 mF cm⁻² at 1 mA cm⁻² current density. When configured as an asymmetric supercapacitor (LaFeCoOOH//Activated Carbon (AC)) using 6 m KOH electrolyte, the device achieves an exceptional energy density of 118.52 µWh cm⁻² while delivering a power density of 1700 µW cm⁻², highlighting its dual functionality for both energy conversion and storage applications. Hence, this study provides a new perspective for the exploration of new multifunctional transition metal composites modified with rare earth elements for energy storage and conversion applications.