Pulsed away

Abstract

Using carbon-supported platinum nanoparticles modified with oleylamine — a conventional ligand for the synthesis of colloidal nanoparticles — the team tested the effect of square-wave potentials that alternate steps at 1.24 V (referred to as the oxidation potential) and 0.20 V (reduction potential). Unlike conventional CV activation, which requires long times (1,200 s) to fully expose the platinum surface, the square-wave potential approach achieves complete ligand removal — estimated by measuring the electrochemical surface areas — in just 40 s. Importantly, post-treatment spectroscopic evaluation confirms the structural integrity of the nanoparticulate catalyst, which also retains its intrinsic activity during electrochemical methanol oxidations tests. The authors also showed the generality of the approach with respect to the removal of different ligands (such as pyridine, butylamine, 1-dodecanethiol or triphenylphosphine) from the surface of Pt nanoparticles. Moreover, in situ electrochemical infrared and Raman spectroscopies were applied to study the surface intermediates generated during the reaction, revealing the contribution of both oxidative and reductive potentials to the process. Finally, the strategy was extended to Pt-alloy nanoparticles proving generality with the respect to the type of nanoparticle.

This simple approach is expected to impact the testing and development of different electrocatalysts. It remains to be seen if the method can also be useful for nanoparticle systems beyond electrocatalysis, for instance for particles traditionally employed under different reactive environments such as gas–solid interfaces under thermal conditions.