A phase-optimized NiFe-LDH/NiB heterostructure as an efficient and durable oxygen evolution electrocatalyst in alkaline media

Abstract

Nickel–iron layered double hydroxide (NiFe-LDH) has attracted considerable attention as an efficient electrocatalyst for the oxygen evolution reaction (OER) in alkaline media. However, the irreversible phase transition from γ-Ni(Fe)OOH to β-Ni(Fe)OOH, which is based on the low thermodynamic stability of γ-Ni(Fe)OOH, results in the poor durability of NiFe-LDH. To address this, this study designs an NiFe-LDH/NiB heterostructure (NiFe@NiB). Because NiB acts as an electron acceptor, it modulates the Ni oxidation state (Ni³⁺ → Ni^(3+δ)+) and facilitates the β-to-γ phase optimization. Notably, NiFe@NiB maintains a higher γ-phase fraction during OER cycling and exhibits an expanded 2D layered structure, which is a structural feature of the active γ-phase. In conclusion, NiFe@NiB requires 75 mV lower overpotential to achieve 10 mA cm⁻² and one-fifth degradation rate with 93.2% reduced Fe leaching over 120 hours of durability test compared to NiFe-LDH. This work presents a compelling strategy for designing efficient and durable electrocatalysts for sustainable hydrogen production.