Additively Manufactured Iron‐Based Bulk Metallic Glass Composite Electrocatalysts: Effect of Microstructural States on the Oxygen Evolution Reaction Activity

Abstract The influence of crystallinity on the electrocatalytic activity of complex alloys requires further clarification to optimize their properties. In this work, the electrocatalytic properties of additively manufactured Fe‐based bulk metallic glasses (BMG), namely, their activity toward the oxygen evolution reaction are studied in alkaline media. Laser powder bed fusion (PBF‐LB/M) is applied to fabricate electrodes with different numbers of glass‐forming Fe₇₅Mo_14.3Ni_1.6P₆C_2.2B₁ layers on 316L stainless steel substrates. Electrochemical and physicochemical characterization techniques are used to characterize the surface of the electrodes both as‐built and after annealing and devitrification. Although different process parameters lead to similar electrochemical responses, certain differences are observable. Namely, the thickness of the BMG‐coating and the ratio of crystalline/amorphous phases seems to determine the catalytic activity. In particular, it is noticeable that partially crystallized samples display higher activities, contrary to some previous observations on different materials. The measurements indicate a complex interplay between crystallinity and active surface area that determines the electrochemical properties of the investigated electrode material.