Stabilize the (Ni, Fe)OOH Active Phase through Interfacial Engineering for Efficient Oxygen Evolution Reaction under pH-Neutral Media

While (Ni, Fe)OOH derived from NiFe-layered double hydroxides (NiFe-LDHs) exhibits significantly enhanced oxygen evolution reaction (OER) activity in concentrated alkaline media, their stability is compromised in strongly corrosive electrolytes. Here, we engineered the heterostructure by integrating the active (Ni, Fe)OOH phase with two-dimensional (2D) materials, designated as (Ni, Fe)OOH/2D, where the 2D materials include graphene, graphene, and g-C₃N₄. Unlike conventional methods that connect the entire NiFe-LDHs to 2D materials (NiFe-LDHs/2D), our interface-engineered architecture retains the active (Ni, Fe)OOH species. Thereby, (Ni, Fe)OOH/2D catalyst maintains its catalytic activity under neutral or moderately alkaline conditions. Then, our simulations reveal that the (Ni, Fe)OOH/2D heterostructures exhibit a lower overpotential than both NiFe-LDHs and (Ni, Fe)OOH for the OER, indicating the superior OER activity of the heterostructures. Bader charge analysis confirms electron transfer from the 2D material to (Ni, Fe)OOH, inducing a upshift of the d-band center. This electronic modulation enhances the OER activity by optimizing the adsorption energetics of the intermediates. Besides, our calculations reveal that (Ni, Fe)OOH/2D heterostructures effectively weaken the bonding of the rate-determining step (RDS) reactant intermediate of the OER, while strengthening the bonding of the RDS product intermediate, resulting in (Ni, Fe)OOH/2D exhibiting superior OER performance compared to that of the conventional heterostructure NiFe-LDHs/2D. Our findings help pave the way for the development of high-performance OER catalysts with extended pH adaptability from atomic-level structural design.