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The lack of mechanistic understanding and catalyst design principles for alkaline electrolytes, especially for the sluggish oxygen reduction reaction, has impeded the advancement of alkaline fuel cells. Here, in this study, we propose a modified volcano plot and apply this rationale to strategically design Pt nanosheets with PdH_x nanosheets substrates. This catalyst exhibited high stability with a specific activity of 1.71 mA cm⁻² at 0.95 V versus the reversible hydrogen electrode, surpassing the benchmark of Pt/C by 49-fold. Spectroscopic, electrochemical and electron microscopic characterizations revealed that such performance enhancement originated from tensile-strained Pt{111} facets, improving oxidative stability and suppressing carbonmore » corrosion. In fuel cell testing, the catalyst enabled a peak power density of 1.67 W cm⁻² with a loading of 10 µg_{PGM Cathode} cm⁻². Further optimization delivered a peak power density of 21.7 W mg⁻¹_{PGM Cathode+Anode} with a total specific catalyst cost US$$\$$$$1.27 kW⁻¹, surpassing the US Department of Energy’s Pt group metal loading and cost targets. This study provides valuable insights into catalyst design for the alkaline oxygen reduction reaction.« less

Transition metal nitride (TMN-) based materials have recently emerged as promising non-precious-metal-containing electrocatalysts for the oxygen reduction reaction (ORR) in alkaline media. However, the lack of fundamental understanding of the oxide surface has limited insights into structure–(re)activity relationships and rational catalyst design. Here, in this work, we demonstrate how a well-defined TMN can dictate/control the as-formed oxide surface and the resulting ORR electrocatalytic activity. Structural characterization of MnN nanocuboids revealed that an electrocatalytically active Mn₃O₄ shell grew epitaxially on the MnN core, with an expansive strain along the [010] direction to the surface Mn₃O₄. The strained Mn₃O₄ shell on themore » MnN core exhibited an intrinsic activity that was over 300% higher than that of pure Mn₃O₄. A combined electrochemical and computational investigation indicated/suggested that the enhancement probably originates from a more hydroxylated oxide surface resulting from the expansive strain. This work establishes a clear and definitive atomistic picture of the nitride/oxide interface and provides a comprehensive mechanistic understanding of the structure–reactivity relationship in TMNs, critical for other catalytic interfaces for different electrochemical processes.« less