Preserving the Exposed Facets of Pt<sub>3</sub>Sn Intermetallic Nanocubes During an Order to Disorder Transition Allows the Elucidation of the Effect of the Degree of Alloy Ordering on Electrocatalysis
Hsiang-Sheng Chen, Tânia M. Benedetti, Vinícius R. Gonçales, Nicholas M. Bedford, Robert W. J. Scott, Richard F. Webster, Soshan Cheong, J. Justin Gooding, Richard D. Tilley
Abstract
Controlling which facets are exposed in nanocrystals is crucial to understanding different activity between ordered and disordered alloy electrocatalysts. We modify the degree of ordering of Pt3Sn nanocubes, while maintaining the shape and size, to enable a direct evaluation of the effect of the order on ORR catalytic activity. We demonstrate a 2.3-fold enhancement in specific activity by 60- and 30%-ordered Pt3Sn nanocubes compared to 95%-ordered. This was shown to be likely due to surface vacancies in the less-ordered particles. The greater order, however, results in higher stability of the electrocatalyst, with the more disordered nanoparticles showing the dissolution of tin and platinum species during electrocatalysis.