Electrodeposition-initiated, self-catalyzed growth of 2D amorphous Fe-group metal-boron alloy mesoporous films.

Two-dimensional mesoporous amorphous metallic films, particularly those based on earth-abundant Fe-group metals (Ni, Co, Fe), are highly promising for various applications due to their high surface area, structural isotropy, and abundant undercoordinated sites. However, synthesizing continuous Fe-group amorphous metallic films with well-defined mesoporosity under mild conditions remains a challenge. Here, we develop an electrodeposition-initiated, self-catalyzed electroless growth strategy, enabling the synthesis of composition-tunable (from binary to quaternary) amorphous Fe-group metal-boron (M-B) mesoporous films (MFs) on various conductive substrates. This approach decouples the nucleation and growth stages, allowing precise control over film thickness, composition, and mesostructure. Thickness-time measurements suggest a self-accelerating growth process, whereas finite-element simulations indicate that substrate-dependent electric-field distributions modulate the nucleation and growth morphology. The synthesized multimetallic amorphous Ni-Co-Fe-B MF demonstrates high oxygen evolution performance and durability in alkaline simulated seawater, making them promising candidates for practical applications. Theoretical insights reveal preferential OH- adsorption over Cl- in the amorphous architecture, which may help mitigate chloride adsorption and facilitate the key reaction step. This study provides a method for synthesizing noble-metal-free amorphous M-B MFs.