Self-Anchored Platinum-Decorated Antimony-Doped-Tin Oxide as a Durable Oxygen Reduction Electrocatalyst

Abstract

The lifetime of commercial proton exchange membrane fuel cells (PEMFCs) is circumscribed by the insufficient durability of commercial catalysts. The use of metal oxide supports in place of carbon significantly increases electrocatalyst durability. Herein, following density functional theory predictions of improved platinum (Pt) stability on antimony-doped tin oxide (ATO) supports, we synthesized ATO whose morphology and crystal structure were engineered using a Pt-anchoring technique. X-ray photoelectron spectroscopy indicated that the Pt anchor sites aided in the reduction of Pt precursors to Pt on the ATO surface. X-ray absorption near-edge spectroscopy revealed the existence of strong metal–support interactions (SMSIs) between Pt and ATO. The combination of SMSIs and high control over Pt dispersion enabled the Pt/Pt-aerogel-ATO (Pt supported on aerogel ATO with Pt anchor sites) electrocatalyst to achieve 2 × the area-specific activity of Pt/C in ex situ testing. In a H2/air PEMFC, Pt/Pt-aerogel-ATO cathodes enabled 20% higher peak power density and <1/6 the loss of active surface area as compared to Pt/C. In a PEMFC under rigorous potential cycling, the Pt/Pt-aerogel-ATO retained its initial peak power density as opposed to a 58% loss for Pt/C. Furthermore, cost models indicate that Pt/Pt-aerogel-ATO is 26% less expensive than Pt/C over its useful lifetime.