PtRu nanoparticles supported on p-phenylenediamine-functionalized multiwalled carbon nanotubes: enhanced activity and stability for methanol oxidation

A facile method was developed for preparation of PtRu nanoparticles/multiwalled carbon nanotubes (MWCNTs) electrocatalysts for methanol oxidation. Starting from pristine MWCNTs, high dispersion of PtRu nanoparticles was directly assembled on the side wall of MWCNTs by using p-phenylenediamine (PPDA) as the inter-linker. FTIR and Raman spectroscopy examinations show that PPDA can be immobilized on pristine MWCNTs by π-π stacking, and the integral structure of MWCNTs was preserved after modification. TEM and XRD investigations show that the face-centered cubic (fcc) Pt structure of PtRu alloy nanoparticles with average diameter 3.5 ± 0.5 nm are uniformly supported on the surface of PPDA-functionalized MWCNTs (PPDA-MWCNTs). The resulting PtRu/PPDA-MWCNTs catalyst exhibits a more negative onset potential (0.15 V) than PtRu/MWCNTs (0.33 V), showing the higher electrocatalytic activity towards methanol oxidation, while its forward peak current density (731.6 mAmg−1 of Pt) is 1.66 times higher than that of PtRu/MWCNTs (440.5 mAmg−1 of Pt). The PtRu/PPDA-MWCNTs catalyst also shows significantly enhanced steady-state current and long-term stability. The smaller size, better dispersion, and higher electrochemical surface area (73.5 m2 g−1) of the PtRu nanoparticles on PPDA-MWCNTs result in superior electrocatalytic performance towards methanol oxidation. This work may provide an efficient method to fabricate MWCNTs-supported superior noble metal catalysts for broad applications in energy systems and sensing devices.