Electrocatalytic activity of platinum submonolayers on defect-rich Au(111)

The influence of a high defect density on an Au(111) surface on electrocatalytic properties of electrochemically deposited Pt nanoislands was evaluated. Therefore, the electrocatalytic activities of Pt nanoislands on a defect-poor and on a defect-rich Au(111) surface were compared for the hydrogen reactions (HER and HOR). These investigations were expected to yield higher activities of defect-rich surfaces since the spillover effect should be promoted. In fact, our expectations were met: The electrocatalytic activity of Pt nanoislands on defect-rich Au(111) was found to be more than twice as high as on defect-poor Au(111). This was thought to originate from a higher reactivity of the defect-rich Au surface, which plays a fundamental role for the spillover process. Another factor, which has to be taken into account, is the influence of differences in the hydrogen adsorption energies of Pt nanoislands, which are supported on Au(111) terraces and on Au(111)-defect sites. Hence, different electrocatalytic activities can also be due to different hydrogen adsorption energies.