Novel electrodeposition media to synthesize CoNi-Pt Core@Shell stable mesoporous nanorods with very high active surface for methanol electro-oxidation

Abstract

Three strategies have been tested to obtain stable mesoporous CoNi@Pt nanorods with a very high effective area and good performance for methanol electro-oxidation. They are based on, firstly, an electrochemical synthesis of the CoNi nanorods using three clearly different systems (micellar solution, water-in-ionic liquid microemulsion and suspension of polystyrene nanoparticles), and, secondly, a posterior platinum shell formation by interfacial replacement reaction. The obtained nanorods have been compared with pure platinum ones prepared following the three methods. The synthesized mesoporous platinum nanorods already show very good performance for methanol oxidation in comparison with compact ones or the usual Pt/C catalyzers, but the mesoporous CoNi@Pt nanorods have demonstrated much better performance for methanol oxidation, due to the more active platinum atoms in the shell of platinum than in the bulk, the higher good poison tolerance and the lower cost of the material -owing to the drastic saving in platinum in the nanostructures-. The mesoporous CoNi@Pt nanorods obtained from the water-in-ionic liquid microemulsion are the best candidates as electrocatalysers because they provide a significantly higher mass-normalized current density (1326 mA mg-1), a good stability in the sulfuric acidic medium and significant electrocatalytic stability under continuous operating conditions.