STM investigation of RuOx submonolayer nanostructures on Pt(111) for alkaline HER

Visualizing a model catalyst surface on the atomic scale can help to explain its activity and its properties observed during electrochemical characterization. In this work, carried on in UHV, a Pt(111) single crystal is firstly characterized and then covered with submonolayer films of RuOx deposited via hot sample chemical vapor deposition (CVD) in an oxygen pressure. The model catalyst, with various coverages obtained by changing deposition time, is initially characterized in UHV via LEED, XPS and STM. This last technique was abundantly used to understand the deposition process and the growth of the film. Afterwards, the sample activity for alkaline HER is tested in an electrochemical cell to correlate the coverage, composition and shape of the adsorbates to the mechanisms affecting the catalysis, in an effort to understand whether a bifunctional mechanism between platinum and ruthenium is at play for achieving the evolution of hydrogen.