DFT Calculations of the Electrochemical Adsorption of Sulfuric Acid Anions on the Pt(110) and Pt(100) Surfaces

Abstract

We have studied the electrochemical adsorption of sulfuric acid anions on the Pt(110) and Pt(100) surfaces employing calculations based on the density functional theory. Our results show that bisulfate, as well as hydronium–sulfate ion pairs, can be adsorbed on Pt(110) at electrode potentials below 0.4 V vs. the reversible hydrogen electrode (RHE). On the other hand, only bisulfate is stable on Pt(100) at potentials below 0.6 V (RHE). At a higher potential, the results indicate that only sulfate is stable on these surfaces. The sulfuric acid anions are two-fold coordinated on Pt(110) and Pt(100), which contrasts with the Pt(111) surface where the adsorbed conformation of the anions can change from a two-fold to three-fold coordination. These differences in the coordination of the adsorbed sulfuric acid anions on Pt(111), Pt(110), and Pt(100) could help rationalize the dissimilar voltammetric features of these surfaces in sulfuric acid solutions.