Unveiling the role of catalytically active MXene supports in enhancing the performance and durability of cobalt oxygen evolution reaction catalysts for anion exchange membrane water electrolyzers

The role of 2D transition metal carbides, also known as MXenes, as active catalyst supports in Co-based oxygen evolution reaction (OER) catalysts was elucidated through a combination of experimental and computation electrochemistry. Through facile seeding of commericial Co nanoparticles on three different MXene supports (Ti3C2Tx, Mo2Ti2C3Tx, Mo2CTx), Co@MXene catalysts were prepared and their electrochemical properties examined for alkaline OER electrocatalysts. The OER activity enhancement of Co was significantly improved for Mo2CTx and Mo2Ti2C3Tx supports, but marginal on the Ti3C2Tx in rotating disk electrode and membrane electrode assembly tests. The Co@Mo2CTx exhibited the highest anion exchange water electrolysis performance of 2.11 A cm-2 at 1.8 V with over 700 hours of stable performance, exceeding previous benchmarks for non-platinum group (non-PGM) metal OER catalysts. The superior performance was attributed to the strong chemical interaction of Co nanoparticle with the Mo2CTx MXene support. Insights into the electrochemical and chemical oxidation according to MXene type as related to cell durability, as well the effect of electrical conductivity and inherent boosting of electrocatalytic activity of Mo-based MXenes elucidated through density functional theory (DFT) calculations helped explain the performance and durabilty enhancement of Mo-based MXene supports over Ti3C2Tx supports.