Structural inheritance and redox performance of nanoporous electrodes from nanocrystalline Fe_85.2 B_10-14 P_0-4 Cu_0.8 alloys

Nanoporous electrodes have been fabricated by selectively dissolving the less noble α-Fe crystalline phase from nanocrystalline Fe_85.2 B_14–x P_x Cu_0.8 alloys (x= 0, 2, 4 at.%). The preferential dissolution is triggered by the weaker electrochemical stability of α-Fe nanocrystals than amorphous phase. The final nanoporous structure is mainly composed of amorphous residual phase and minor undissolved α-Fe crystals and can be predicted from initial microstructure of nanocrystalline precursor alloys. The structural inheritance is proved by the similarity of the size and outlines between nanopores formed after dealloying in 0.1 M H₂ SO₄ and α-Fe nanocrystals precipitated after annealing of amorphous Fe_85.2 B_14−x P_x Cu_0.8 (x = 0, 2, 4 at.%) alloys. The Redox peak current density of the nanoporous electrodes obtained from nanocrystalline Fe_85.2 B₁₀ P₄ Cu_0.8 alloys is more than one order higher than those of Fe plate electrode and its counterpart nanocrystalline alloys due to the large surface area and nearly-amorphous nature of ligaments.