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

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 H-2/O-2. The optimization or elimination of the alkaline pretreatment will simplify the fabrication process for fuel cells and thus reduces their manufacturing costs. (c) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.