Boron Nitride Interfacial Confinement of FeNi Layered Double Hydroxide Reconstruction for Durable Overall Water Splitting.

Abstract

Developing durable and highly active earth-abundant electrocatalysts is crucial for large-scale water splitting. While NiFe-based layered double hydroxides (LDHs) are promising for the oxygen evolution reaction (OER), their stability is often compromised by the irreversible structural degradation of their dynamically reconstructed active phase. Rationally controlling this reconstruction to simultaneously enhance intrinsic activity and structural stability remains a formidable challenge. Herein, we propose and demonstrate a strategy by engineering a crystalline boron nitride (BN) interface onto a FeNi LDH precatalyst. This single interface achieves a unique dual function. Theoretical calculations and operando spectroscopy reveals that the BN nanolayer first functions as a physical corral, effectively immobilizing the in situ formed FeNiOOH nanoclusters and preserving their high dispersion to ensure structural stability. Furthermore, this interface transcends the role of a passive shield; theoretical calculations confirm it also acts as a powerful electronic modulator, inducing interfacial charge transfer that results in a crucial upward shift in the Fe/Ni d-band center. This synergistic mechanism breaks the OER scaling limitations by lowering the energy barrier for the rate-determining step. As a result, the catalyst exhibits exceptional bifunctional performance, requiring low overpotentials of just 234 mV for OER and 98 mV for HER to achieve 10 mA cm^-2. This enables a two-electrode electrolyzer to reach 10 mA cm^-2 at a cell voltage of only 1.57 V with outstanding long-term durability. This work establishes a new paradigm, demonstrating that rational d-band tuning via crystalline heterointerfaces is a powerful strategy for designing advanced synergistic electrocatalysts.