Rational design of high-performance low-loading oxygen reduction catalysts for alkaline fuel cells

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 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 carbon 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.