One-step synthesis of the hydrophobic conical Co-Fe structures – the comparison of their active areas and electrocatalytic properties

Enhancement of the surface of the catalyst is desirable in the interest of mass transport maximizing. However, without a well-defined method of determination of its active surface, catalyst deposited with different conditions cannot be accurately compared. In this work, Co-Fe alloy cones were synthesized from the electrolyte containing ammonium chloride as a crystal modifier. It controls the direction of the deposit growth, and consequently, develops the active surface area. Moreover, the influence of the direction of the applied magnetic field on the ferromagnetic Co-Fe alloy was investigated. It affected noticeably the morphology and composition of layers and therefore, the catalytic activity of the samples in the Hydrogen Evolution Reaction (HER). Linear Sweep Voltammetry (LSV) measurements were used to test the catalytic activity in 1 M NaOH electrolyte. The expected development of the real active surface area was determined using two different methods: Brunauer-Emmett-Teller (BET) and Helmholtz Double-Layer Capacitance (DLC). Results show that no specific value of the sample surface multiplication can be found based on these methods. All conical structures were hydrophobic.