Constructing heterojunction interface between Co-Fe layered double hydroxide and Ni-Fe metal–organic framework as efficient oxygen evolution electrocatalyst: Mechanism insights into CoOOH-FeOOH-NiOOH ternary system

Abstract

The creation of available and cost-effective non-noble-metal electrocatalysts for oxygen evolution was of considerable practical significance. In this study, we introduced a CoFe-layered double hydroxide (LDH) and NiFe metal–organic framework (MOF) electrocatalyst that was supported on nickel foam (NF) for oxygen evolution reaction (OER). The coordination structure between Co/Ni and Fe was modulated by varying the Fe content, which enhances the electron tunneling ability between CoFe-LDH and NiFe-MOF. Additionally, characterization techniques confirmed the synergistic interactions of the active sites Co²⁺/Co³⁺, Ni²⁺/Ni³⁺ and Fe²⁺/Fe³⁺ in the OER process. Calculations using density-functional theory (DFT) substantiated the swift electron transfer that occurs among the ternary active substances CoOOH, FeOOH, and NiOOH during the generation of OER in strong alkaline environments, which was enhanced by synergistic effects and the efficient adjustment of electronic interactions. CoFe-LDH@NiFe-MOF fully exposes the active centers within its nanosheet structure, featuring a hierarchical porous architecture that promotes rapid charge and mass transfer. The measured overpotential was found to be 225 mV with an current density of 10 mA cm⁻², and Tafel slope was recorded at 28.10 mV dec⁻¹. The results presented show that the as-prepared electrocatalysts exhibited superior activity in OER compared with commercial RuO₂ catalysts. Furthermore, this self-supported electrocatalyst displays impressive durability, as there was no observed degradation in its activity over a continuous 60h operation period. This research illustrates a straightforward and practical approach to developing effective catalysts for water oxidation, achieving both highly catalytic competence and long-term fixity.