Editors’ Choice—Uncovering the Role of Alkaline Pretreatment for Hydroxide Exchange Membrane Fuel Cells

Abstract

Alkaline pretreatment is perceived as an essential step for high-performance hydroxide exchange membrane fuel cells (HEMFCs), but its exact function is not fully understood. Here we show that alkaline pretreatment is only necessary when carboxylates are generated from platinum- or palladium-catalyzed oxidation of primary alcohol solvents during membrane electrode assembly (MEA) fabrication. When alkaline pretreatment is needed, bicarbonates are a better choice than the most commonly used hydroxide bases. We further demonstrate that MEAs with Pt/Pd-free catalysts, which can be used in HEMFCs, exhibit a better performance without the alkaline pretreatment: a voltage of 0.64 V at 1.0 A cm−2 and a peak power density of 0.69 W cm−2 in H2/O2. The optimization or elimination of the alkaline pretreatment will simplify the fabrication process for fuel cells and thus reduces their manufacturing costs.