Bimetallic Pt–M (M = Fe, Co, Ni) nanobunches composed of ultrathin nanowires with strong synergy and rich surface defects for enhanced methanol oxidation electrocatalysis

Abstract

High performance and cost-effective electrocatalysts have been intensively pursued to push forward the commercialization of direct methanol fuel cells (DMFCs). Rationally designing the architecture and composition of Pt-based alloys can improve the utilization of Pt, optimize their electronic configurations and promote the electrocatalytic performance. In this work, a series of bimetallic Pt–M (M = Fe, Co, Ni) nanobunches (NBs) composed of parallel ultrathin nanowires with a diameter of ∼2 nm were fabricated via a simple one-pot method. Various characterization techniques show that Pt–M NBs have more catalytic active sites, abundant surface defect sites and a strong electronic coupling effect between Pt and M, which are beneficial to improving electrocatalytic performance for the methanol oxidation reaction (MOR). By tuning the ratio of Pt and M and the kind of M, the PtNi NBs with a Pt/Ni atomic ratio of 1 : 1 exhibits the highest mass and area activities of 908.08/1162.21 mA mg⁻¹_Pt and 84.34/107.65 mA cm⁻² in 0.5 M H₂SO₄/1.0 M KOH solutions among these Pt–M NBs. And its mass and area activity are 3.54/5.23-fold and 2.45/3.59-fold higher than those of commercial Pt/C in acidic and alkaline media. Furthermore, it also displays more resistance against poisoning and outstanding long-term stability in comparison with pure Pt NBs and the Pt/C catalyst.