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 gamma-Ni(Fe)OOH to beta-Ni(Fe)OOH, which is based on the low thermodynamic stability of gamma-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+delta)+) and facilitates the beta-to-gamma phase optimization. Notably, NiFe@NiB maintains a higher gamma-phase fraction during OER cycling and exhibits an expanded 2D layered structure, which is a structural feature of the active gamma-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.