Fast Removing Ligands from Platinum-Based Nanocatalysts by a Square-Wave Potential Strategy

Developing effective methods to remove ligands from the surface of nanoparticles (NPs) is crucial for obtaining surface-cleaned nanocatalysts. In this manuscript, we develop a square-wave potential (SWP) strategy that efficiently removes ligands from the surface of platinum (Pt)-based nanocatalysts within 1 min (40 s), achieving a removal efficiency 30 times higher than that of traditional cyclic voltammetry cycling. Comprehensive analyses of physical characterization and catalytic performance confirm the effectiveness of the SWP strategy. In situ electrochemical infrared and Raman spectroscopy show that the oxidation potential (1.24 V) can replace the Pt-N coordination bond with a Pt─O covalent bond to form the intermediate state of Pt-O-NH₂R during ligand removal, while the reduction potential (0.20 V) can detach the ligand from the surface of Pt. Moreover, the SWP strategy is versatile, extending the efficient removal of various ligands from the surface of Pt and the oleylamine ligand from Pt-based alloy nanocatalysts. The efficient removal of ligands from nanocatalysts is critical for ensuring the reproducibility of electrocatalytic results and for obtaining clean catalysts to reveal intrinsic effects in nanocatalysis.