Boosting the Catalytic Performance of Iron Phosphide Nanorods for the Oxygen Evolution Reaction by Incorporation of Manganese

The lack of efficient and stable oxygen evolution reaction (OER) catalysts comprising inexpensive Earth-abundant materials limits the viability of water splitting as a clean and renewable source of energy. In this work, we report the synthesis of homogeneous ternary Fe<sub>2–<i>x</i></sub>Mn<sub><i>x</i></sub>P nanorods with control of Mn incorporation (0 ≤ <i>x</i> ≤ 0.9) from the solution-phase reaction of manganese and iron carbonyl complexes with trioctylphosphine. The OER activity of Fe<sub>2–<i>x</i></sub>Mn<sub><i>x</i></sub>P nanorods dramatically increases with the incorporation of Mn (overpotential as low as 0.44 V at 10 mA/cm<sup>2</sup> for <i>x</i> = 0.9), and the overpotential can be further decreased (by nearly 0.1 V) by postdeposition annealing. The enhanced OER activity and stability, along with the abundance and availability of Fe and Mn, make bimetallic manganese–iron phosphides a promising class of materials for more cost-effective and efficient water oxidation catalysis.