Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis

Surface ligands play an important role in shape-controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.93 +/- 0.17 nm in thickness) by simply aging the colloidal suspension. The aged Pd NSs show well-preserved morphology, together with significantly enhanced stability toward both e-beam irradiation and electrocatalysis (e.g., ethanol oxidation). It is revealed that the slow desorption of PVP during aging forces the re-exposed Pd atoms to reorganize, facilitating the surface to transform from being nearly perfect to defect-rich. The resultant Pd NSs with abundant defects no longer rely on surface ligand to stabilize the atomic arrangement and thus show excellent structural and electrochemical stability. This work provides a facile and effective method to maintain the integrity of colloidal nanocrystals by slowly removing the surface ligand. We report an effective method to remove the surface ligand from Pd nanosheets by simply aging the sample in ethanol at room temperature. This slow process allows for atomic reconstruction without altering the sheet morphology. When exposed to e-beam irradiation or working as an electrocatalyst toward ethanol oxidation, the aged Pd nanosheets show enhanced stability.image

Automated summary

Surface ligands play an important role in shape-controlled growth and stabilization of colloidal nanocrystals. This study demonstrates a method to slowly remove surface ligands from Pd nanosheets, resulting in enhanced stability and structural characteristics. The slow removal of ligands promotes surface reconstruction and increases the stability of the nanosheets, making them promising for applications in electrocatalysis and other fields.