The role of ruthenium in improving the kinetics of hydrogen oxidation and evolution reactions of platinum

Modifying Pt surfaces by foreign metals with a higher oxophilicity is a promising approach to improve the kinetics of hydrogen evolution and oxidation reactions. The role of foreign metals, however, is not fully understood. Here we study Ru-modified Pt as a model system to understand the underlying mechanisms in activity improvement through combining in situ infrared spectroscopy and theoretical calculations. In an alkaline solution, the hydrogen evolution and oxidation reaction activity of Ru-modified Pt is proportional to the Ru coverage due to the strain and electronic effects of the Pt substrate, which lower the energy barrier of the rate-determining Volmer step; these are the governing reasons for the improved catalytic activities. This work not only deepens our understanding of hydrogen electrocatalysis mechanisms, but also provides guidelines for the rational design of advanced electrocatalysts. Modifying Pt surfaces with highly oxophilic metals can increase the hydrogen evolution and oxidation performance in alkaline media, but the underlying mechanism remains elusive. Now, it is demonstrated that the activity improvement of Ru-modified Pt mainly originates from the strain and electronic effects rather than an alternative bifunctional mechanism.