Superimposed OER and UOR performances by the interaction of each component in an Fe–Mn electrocatalyst

The oxygen evolution reaction (OER) and alternative urea oxidation reaction (UOR) are both important half reactions correlated with hydrogen production. Transition metal based catalysts with double metal composition exhibit excellent electrocatalytic performance for the OER or UOR due to their synergetic effect and coupling of different active sites. However, the development of OER/UOR bifunctional electrocatalysts is unsatisfying and the role of each metallic active site in the OER and UOR is still unclear. Herein, we report a Fe-Mn based OER and UOR bifunctional catalyst through a simple one-step electrodeposition method. For the OER, the introduction of Mn improves the conductivity of the catalysts and fine-tunes the electron density of the Fe active sites. For the UOR, both Fe and Mn act as active sites and their coupling effect further improves the UOR activity. The catalyst with the optimal Mn/Fe ratio achieved an overpotential of 237 mV for the OER and a potential of 1.35 V for the UOR at 100 mA cm^-2. This study provides a simple synthesis protocol for constructing bifunctional catalysts for green hydrogen production.