Stabilization of Pt nanoparticles at the Ta2O5-TaC binary junction: an effective strategy to achieve high durability for oxygen reduction

摘要

The fabrication of platinum (Pt)-based electrocatalysts with high electrochemical durability is a key prerequisite for the practical application of proton exchange membrane fuel cells (PEMFCs). In this work, we present an effective and scalable strategy to strongly stabilize Pt nanoparticles at a Ta-based (Ta2O5-TaC) binary junction formed by a controllable carbothermal phase conversion process, affording stable Pt-Ta2O5-TaC triple interfaces for durable catalysis of the oxygen reduction reaction (ORR). Our strategy utilizes a robust corrosion-resistant support for Pt nanoparticles involving a hollow-structured Ta2O5-TaC composite anchored on a thin carbon skeleton; the presence of the composite inhibits corrosion of the carbon support. The resulting hybrid support overcomes the drawbacks commonly associated with metal oxides and has a large specific surface area and high electrical conductivity owing to the presence of TaC and the carbon skeleton. X-ray absorption near edge structure analysis indicates the presence of strong interactions between Pt and Ta2O5-TaC that induce a surface electron delocalization of Pt and ensure the strong anchoring of Pt nanoparticles. When used as a catalyst for the ORR, the Ta2O5-TaC/C supported Pt electrocatalyst has high mass (0.297 A mg(Pt)(-1)) and specific (0.424 mA cm(-2)) activities (respectively 3.7 and 3.2-times those of commercial Pt/C) at 0.9 V. Furthermore, the electrocatalyst exhibits an outstanding electrochemical durability without any obvious degradation after 10 000 potential cycles in 0.1 M HClO4 solution, significantly outperforming commercial Pt/C which suffers 107 mV loss of half-wave potential. Our synthesis strategy offers a new avenue for developing highly durable Pt-based electrocatalysts with high activity which should have applications in practical PEMFCs.