Enhanced Redox properties of amorphous Fe63.3-83.3Co0-20Si4B8P4Cu0.7 alloys via long-term CV cycling

Abstract

Effect of partial substitution of Fe by Co on the Redox properties and cyclicity of amorphous Fe83.3Si4B8P4Cu0.7 alloy has been investigated in 0.5 M KOH solution by short-term and long-term cyclic voltammetry (CV). Redox performance of amorphous Fe83.3-xCoxSi4B8P4Cu0.7 (x = 0, 1, 4, 10 and 20 at.%) alloys is enhanced by the partial substitution of Fe by Co of 1–20 at.%, and the best chemical composition is considered to be Fe79.3Co4Si4B8P4Cu0.7 on the basis of the highest Redox peak current density after short-term CV cycling. The flake-shaped FeOOH, CoOOH and/or Fe-oxides and Co-oxides form and become more and more with an increasing of the cycle numbers. After 3000 cycles of the long-term CVs, amorphous Fe79.3Co4Si4B8P4Cu0.7 alloy also exhibits the superior and stable Redox properties with two times higher oxidation peak current densities than amorphous Fe83.3Si4B8P4Cu0.7 alloy. Redox peak current densities after long-term CV cycling are enhanced more than 200 times due to the octahedral crystalline Fe3O4, Co3O4 and CoO with a large surface area in comparison to those after the short-term CVs. The substitution of Fe by 4 at.% Co is considered to be the optimal chemical composition for the enhancement of Redox properties and high stability during the long-term CV cycling.