Dual adsorbate mechanism in OER process achieved by the surface nitridation of the polydopamine modified electrodes

The rate determining oxygen evolution reaction (OER) remains a challenge for hydrogen production through water electrolysis. Currently, OER mechanism of catalysts was regarded either following the adsorbate evolution mechanism (AEM) pathway, or the lattice oxygen oxidation mechanism (LOM) pathway. The LOM driven catalysts can directly form O-O bonds, thus accelerating the overall reaction. However, due to the dynamic formation of lattice oxygen, the leaching of uncoordinated metal ions usually leads to poor stability. Balancing the OER activity and stability in the LOM driven catalysts remained challenging. Herein, a catalyst electrode with emerged dual adsorbate mechanism (DAM) was constructed via the coordination of polydopamine and nitridation of a series of bimetallic oxides precursors (FeCo, FeNi, FeCu and CoCu). In the DAM driven electrode, both the metal center and lattice oxygen center participate in the OER cycles and formed the triangular *O-M-*O key intermediate, significantly reducing the energy barrier of the OER process, resulting in excellent OER activity and stability. The proposed DAM mechanism was verified by the experimental and theoretical calculation. Excellent OER performance was achieved in FeCo based electrodes with an over potential of 194/253 mV at a current density of 10/100 mA cm⁻² with greatly enhanced durability.