Platinum–tin as a superior catalyst for proton exchange membrane fuel cells

Abstract

This work reports on the synthesis of a platinum (Pt)–tin (Sn) catalyst supported on Vulcan carbon (VC) for the superior electrooxidation of molecular hydrogen at the anode and electroreduction of molecular oxygen at the cathode of a proton exchange membrane fuel cell. The synthesis was done by using the polyol process. The resulting electrocatalyst with a Pt/Sn mass ratio of 3 (PtSn/VC(3)) demonstrated superior electrocatalytic activity of 3- and 1.4-fold over Pt/VC (synthesized as a reference catalyst) for the reduction of oxygen and oxidation of hydrogen, respectively. The developed PtSn/VC(3) catalyst also demonstrated a greater mass activity of 373 mA mg_Pt⁻¹, i.e. a 2.4-fold improvement compared to Pt/VC for oxygen reduction. The superiority of PtSn/VC(3) was further confirmed upon operation in a self-breathing fuel cell. A maximum power density of 96 mW cm⁻² was observed, i.e. a 45% improvement in terms of power density as compared to Pt/VC. In addition, this new PtSn/VC(3) catalyst demonstrated remarkable stability under accelerated stress test where a fuel cell performance degradation of 9% was observed after 60 000 fuel cell cycles with a 85% of maximum power density retention.