Electrode dynamics from first principles

The investigation of electrode dynamics has been a major topic in the field of electrochemistry for a century. Electrode dynamics consist of electron transfer reactions that give rise to, or are caused by, a bias voltage, and are influenced by surface catalysis, electrolyte solution, transport of electrons and ions. The first-principles molecular dynamics simulation of the electrochemical system has been hampered by the difficulty to describe the bias voltage and the complex solution-electrode interface structure. Here we utilize a new algorithm called the effective screening medium to characterize the biased interface between platinum and liquid water, revealing the microscopic details of the first, Volmer, step of the platinum-catalyzed hydrogen evolution reaction. By clarifying the important roles played by both the water and the bias, we show why this reaction occurs so efficiently at the interface. Our simulations make a significant step towards a deeper understanding of electrochemical reactions.