Cyclic Voltammograms for H on Pt(111) and Pt(100) from First Principles

Cyclic voltammetry is a fundamental experimental method for characterizing electrochemical surfaces. Despite its wide use, a way to quantitatively and directly relate cyclic voltammetry to ab initio calculations has been lacking. We derive the cyclic voltammogram for H on Pt(111) and Pt(100), based solely on density functional theory calculations and standard molecular tables. By relating the gas phase adsorption energy to the electrochemical electrode potential, we provide a direct link between surface science and electrochemistry.

Figure 1

Differential adsorption energy $\Delta E$ for H on Pt(111) and Pt(100). Part (a) shows the effect of a water bilayer and electric field ($ϵ$) for the Pt(111) electrode. In parts (b) and (c) $\Delta E$ is plotted vs the number of H nearest neighbors on the surface and the H coverage, respectively.

Figure 2

Cyclic voltammograms for H adsorption and desorption from Pt(111) and Pt(100) surfaces at different temperatures. The top panels show the result from the analytical model and the bottom two show results from a Metropolis Monte Carlo simulation.

Figure 3

Charge deposition due to hydrogen adsorption vs potential from (a) experiments presented in Ref. 20 and (b) theoretical calculations based only on DFT and molecular tables. The theoretical data are obtained from Eq. (4) and the calculated coverage vs potential. Two different approaches have be used to calculate the theoretical values, see text.