Enhancing fuel cell catalyst layer stability using a dual-function sulfonated silica-based ionomer

Sulfonated-silica ceramic carbon electrodes (SS-CCE) were prepared by an in-situ sol-gel reaction where tetraethylorthosilicate and 3-trihydroxysilyl-1-propanesulfonic acid (TPS) are polymerized in the presence of a commercial Pt/C catalyst. The resultant catalyst layer is a promising candidate for application in proton exchange membrane fuel cells (PEMFCs), however their durability is unproven to date. To that end, we have examined the durability of these SS-CCE’s in fuel cells. The SS-CCE was subjected to an accelerated stress testing (AST) and its fuel cell performance was assessed before and after the AST. Remarkably, the SS-CCE was substantially more durable than a conventional Nafion-based electrode employing the identical Pt/C catalyst. Detailed electrochemical tests and post-mortem analysis of each electrode revealed in addition to its primary function of conducting ions/retaining water, the sulfonated silica ionomer takes on the dual role of stabilizing the Pt/C catalysts through an electronic effect that mitigates Pt nanoparticles Ostwald ripening/agglomeration. The method for producing SS-CCE is highly versatile and could potentially be employed with any fuel cell catalyst. It is therefore proposed that this dual-function ionomer could be paired with almost any Pt/C (or supported alloy catalyst) and extend the operational lifetime of fuel cells without comprising beginning of life performance.