Gram-Scale Synthesis of Unsupported Pt-Rare Earth Nanosponge for Enhanced Stability in Proton Exchange Membrane Fuel Cells

Abstract

Durability is crucial for proton exchange membrane fuel cells (PEMFCs), but the current preferred catalyst, Pt/C, suffers from carbon corrosion and Pt detachment during cycling. In this work, we facilely synthesized carbon-free, unsupported PtLa catalysts on a gram-scale via arc melting coupled with a suction casting process, followed by a dealloying treatment. The resulting PtLa catalysts possess a nanosponge morphology, facilitating mass transport paths for the oxygen reduction reaction. In a PEM single cell, the nanosponge structure demonstrates high utilization of ionomers and proton conductivity with a minimal ionomer loading, and exhibits enhanced activity in the rated voltage region. A mass activity of 0.50 A mgPt-1 is achieved for the nanosponge PtLa-3 (NSPL-3), which is 2.9-fold greater than that of Pt/C (0.17 A mgPt-1), with 94.8% voltage retention and only 22.0% MA loss after 20,000 cyclic durability tests. The high activity retention of NSPL-3 is attributed to the high retention of its nanosponge-like structure, which maintains excellent connectivity between the active sites and leaves sufficient channels for mass transport. This approach holds the potential to propel fuel cell technology forward by providing a cost-effective and robust catalyst alternative.

Keywords: Pt-rare earth catalysts, gram-scale synthesis, nanosponge morphology, unsupported catalyst, proton exchange membrane fuel cells