Controlling Platinum Active Sites on Silver Nanoparticles for Hydrogen Evolution Reaction

Growing Pt on Ag nanoparticles is a promising approach to forming catalysts that present active sites with both Pt and Ag available to improve the activity for the hydrogen evolution reaction (HER). By carefully controlling the concentration of a Pt precursor, the amount of Pt-decorated particles onto the Ag nanoparticles could be controlled to grow Pt islands between 0.6 and 1.5 nm. As a result, the relative amounts of the Ag-Pt active sites could be tuned. The smallest, 0.6 nm Pt islands on the Ag nanoparticle, with the highest ratio of Ag-Pt to Pt-Pt sites was found to have the highest activity and an accelerated Volmer step. DFT modeling showed that the improved performance was due to increased electron density on Pt from electron donation from neighboring Ag that leads to weaker Pt-H binding and the presence of more oxophilic Ag that can bind -OH on the active site that accelerates the water splitting.