ALD-engineered amorphous NiO/crystalline CoFe-PBA heterointerface for high-performance seawater oxygen evolution

Abstract

The practical conversion of seawater to hydrogen faces critical limitations from chloride attack and anodic competition, requiring electrocatalysts with superior robustness. Herein, we constructed an amorphous/crystalline heterointerface catalyst, NiO/CoFe Prussian blue analogues, via low-temperature atomic layer deposition (ALD) toward efficient seawater oxidation. Experimental investigations revealed that utilization of the conformal coating capability of ALD enabled precise integration of a structurally disordered NiO layer onto the crystalline CoFe-PBA framework. This integration resulted in the formation of a robust heterointerface, which synergized the amorphous phase's isotropic corrosion resistance and the crystalline matrix's high conductivity. The catalyst achieved overpotentials of η₁₀ = 257 mV and η₁₀₀ = 301 mV in alkaline seawater. Computational analysis demonstrated that the oxygen-bridged Fe/Co–O–Ni covalent interactions induced strong electronic coupling, modulating the 3d orbital configuration of Fe/Co/Ni sites. This, in turn, led to a downshifted d-band center, optimizing oxygen intermediate adsorption and enhancing the chloride tolerance via Co sites. Notably, 100 hour stability at 100 mA cm⁻² was maintained. This work introduces an ALD-enabled interfacial engineering methodology for fabricating durable heterointerface catalysts tailored for seawater electrolysis hydrogen production.