The Effect of C₆₀ Support on The Electrochemical Activity of Pd and Pt Particles

Engineering nanoparticle-support interactions is a powerful strategy for improving the activity and stability of heterogeneous catalysts. In this contribution, we show how such interactions can also improve the electrocatalytic performance of Pd and Pt nanoparticles. First, we demonstrate how the interactions between Pt nanoparticles and C₆₀ nanosheets lead to higher catalyst activity in alkaline hydrogen evolution reaction (HER) compared to unsupported Pt nanoparticles or Pt nanoparticles on graphene [1]. The nanoscale roughness of the C₆₀(110) support surface helps to stabilize ~2 nm large crystalline Pt particles between appropriately spaced rows of C₆₀ molecules. Our density functional (DFT) simulations reveal the strong polarization of electron density on the interface between similarly sized Pt particles and the C₆₀(110) surface due to the transfer of ~2 electrons from each particle to the support. The polarized electron density on the Pt/C₆₀ interface results in a significant variation of H binding energies, which are known to govern the HER activity of the catalyst. Curiously, our microkinetic modeling shows that such variation dramatically increases the rate of both Volmer, Heyrovsky, and Tafel steps by up to 100 times on the interface sites and decreases HER overpotential by almost 0.1 V at 10 mA/cm²under alkaline conditions, in line with experimental observations. The calculated simultaneous acceleration of both Volmer and Heyrovsky steps indicates that the introduced diversity of the active sites on the nanoparticle-support interface effectively allowed us to overcome the limitations of Sabatier activity volcano for hydrogen evolution reaction on transition metals. Moreover, the interactions between metal nanoparticles and fullerene support can also affect the phase transitions in the former. For example, we show how nanoparticle-support interactions alter the onset electrode potential for β-hydride formation in Pd nanoparticles, which notably changes their electronic structure and catalytic properties. As a result, the activities of Pd/C₆₀catalysts in HER and CO₂ reduction reactions significantly differ from those of unsupported Pd nanoparticles.<br/><br/><b>References:</b><br/>[1] Chen, Aliasgar, Buendia, Zhang, Zhao, Lian, Wen, Yang, Sun, Kozlov, Chen, Wang, <i>Diversity of platinum-sites at platinum/fullerene interface accelerates alkaline hydrogen evolution</i>, <b>Nat. Commun.</b> 2023, 14, 1711