Graphene-quantum-dot-composited platinum nanotube arrays as a dual efficient electrocatalyst for the oxygen reduction reaction and methanol electro-oxidation†

Platinum (Pt) is an excellent electrocatalyst for cathode and anode reactions in direct methanol fuel cells (DMFCs). However, constructing nanostructures with efficient Pt utilization and electrocatalytic activity is a major challenge for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in an acidic medium. Herein, we describe a facile strategy to prepare high activity graphene quantum dot composited Pt nanotubes arrays (GQD-Pt NTAs) with an available porous surface through an electro-codeposition approach. Benefiting from the difference in size between graphene quantum dots and Pt nanoparticles, the GQD-Pt NTAs possess an adjustable porous structure. Moreover, the increased porosity of the GQD-Pt NTAs improves the effective availability of the Pt surface, significantly enhancing the electrocatalytic activity with a high current density of 1.14 mA mu g(Pt)(-1) at 0.90 V (vs. RHE) and 2227.08 mA mg(Pt)(-1) at 0.85 V (vs. RHE) for the ORR and MOR, respectively. This work suggests that combining Pt with nonmetallic quantum dots is indeed an effective approach to address the unsatisfactory utilization and electroactivity of Pt-based nanomaterials.