Toward In Situ Programming Ligand Desorption/Adsorption Dynamics of Metal Nanoparticles in Electrocatalysis.

Ligand effects represent a long-last dilemma in metal nanocatalysis, as organic ligand coordination inevitably blocks active metal sites while maintaining structure stability of nanoparticles. To tackle this challenge, we demonstrate herein a supramolecular interaction-assisted ligand reversible desorption/adsorption strategy for simultaneously achieving catalytic activity and stability of metal nanoparticles. Using atomically precise [Au13(dppe)5Cl2]3+ nanoclusters (NCs; dppe = 1,2-bis(diphenylphosphino)ethane) as paradigm particles, we demonstrate that extensive π-π stacking among dppe ligands retains desorbed ligands near the cluster surface during catalysis, enabling readsorption to original sites after the reactions. Leveraging scanning tunneling microscope break junction techniques, we successfully capture and real-time track such reversible ligand desorption/adsorption dynamics on individual cluster surfaces. This is inherently made possible by the conductance dependence of single cluster on its surface structure, manifesting switchable ligand on/off states by programming external bias voltages. By this way, [Au13(dppe)5Cl2]3+ NCs deliver superior catalytic activity and stability than those without surface π-π interactions, where a stable electrocatalytic performance is recorded at a consistent current density of -40.6 mA cm-2 for over 400 min in the hydrogen evolution reaction. Based on the reversible ligand desorption/adsorption dynamics, we further constructed a stable single-cluster switching device, exhibiting a marked on/off ratio of ∼0.5 orders of magnitude. This work not only provides a precise and accurate strategy to monitor the ligand dynamics at the single cluster/particle level but also underscores the decisive role of ligand dynamics on the catalytic activity and stability of metal and other inorganic nanoparticles.