Using the Surface Oxide Reduction Method to Determine the Surface Area of Pd–Co Alloys

The surface oxide reduction method, a well-established technique for determining the electrochemically active surface area of Pd, is also widely used for Pd–Co alloys. However, comprehensive studies investigating the influence of the alloy composition on the determination of the surface area by the surface oxide reduction method are lacking for this alloy system. To fill this gap, a systematic investigation is conducted by applying the surface oxide reduction method to homogeneous Pd100−xCox alloy samples with different compositions (x = 0−20). The results reveal that full monolayer coverage with surface oxide occurs at lower potentials than for pure Pd and that the surface area determined by this method systematically decreases with increasing Co content, indicating that only the Pd sites are accessible by this method. However, it is demonstrated that by taking the alloy composition into account, the surface area of the whole alloy can also be reliably determined.