Ionic Liquid Modification of High-Pt-Loading Pt/C Electrocatalysts for Proton Exchange Membrane Fuel Cell Application

: Ionic liquid modification for carbon-supported platinum (Pt/C) electrocatalysts to enhance their oxygen reduction reaction (ORR) activity has been well recognized. However, the research has only been reported on the low-Pt-loading Pt/C electrocatalysts, e.g., 20 wt%, while in practical applications, usually high-Pt-loading Pt/C electrocatalysts of 45–60 wt% are used. In this work, ionic liquid modification is systematically investigated for a Pt/C electrocatalyst with 60 wt% Pt loading for its ORR activity in the cathode in proton exchange membrane fuel cells (PEMFCs). Various adsorption amounts are studied on the catalyst surface. Different modification behavior is found. Mechanism exploration shows that the adsorption of ionic liquid mainly happens on the Pt electrocatalyst surface and in the micropores of the carbon support. The highest fuel cell power performance is achieved at an ionic liquid loading of 7 wt%, which is much higher than the 3 wt% reported for the low-Pt-loading Pt/C.

离子液体对碳载铂（Pt/C）电催化剂进行改性以提高其氧还原反应（ORR）活性已得到广泛认可。然而，相关研究仅报道了低铂载量的Pt/C电催化剂，例如20 wt%，而在实际应用中，通常使用45 - 60 wt%的高铂载量Pt/C电催化剂。在这项工作中，针对质子交换膜燃料电池（PEMFCs）阴极中铂载量为60 wt%的Pt/C电催化剂的氧还原反应活性，对离子液体改性进行了系统研究。研究了催化剂表面的各种吸附量，发现了不同的改性行为。机理探究表明，离子液体的吸附主要发生在铂电催化剂表面以及碳载体的微孔中。当离子液体负载量为7 wt%时，燃料电池的功率性能达到最高，这远高于低铂载量Pt/C所报道的3 wt%。