Polyaniline coating enables electronic structure engineering in Fe 3 O 4 to promote alkaline oxygen evolution reaction.

The electronic structure of active sites is of importance for catalysts to achieve an optimized interaction with the intermediates. In this study, a unique organic-inorganic hybrid oxygen evolution reaction electrocatalyst composed of electrochemically inactive conducting polyaniline (PANI) and non-precious Fe-based oxide Fe 3 O 4 is presented. PANI molecules were in situ loaded on Fe 3 O 4 nanoparticles through an efficient and simple process under mild conditions. The electronic structure of Fe 3 O 4 was modulated by creating a strong interaction with PANI molecules, leading to enhanced activity and stability of the catalyst to achieve 10 mA cm -2 geometrical current density at overpotential of 265 mV in 1 M aqueous KOH solution. This work demonstrates that a highly efficient electrocatalyst can be achieved by molecular modification and provides a novel strategy for the optimization of the inactive non-precious catalysts.