Electrochemically Driven Coordination Tuning of FeOOH Integrated on Carbon Fiber Paper for Enhanced Oxygen Evolution

Coordination tuning of catalysts is a highly effective strategy for activating and improving the intrinsic activity. Herein, a Co-engineered FeOOH catalyst integrated on carbon fiber paper (Co-FeOOH/CFP) is reported, which realized a great improvement of the oxygen evolution activity by tuning the coordination geometry of the Fe species with an electrochemically driven method. Experiments and theoretical calculation demonstrate that the FeO bonds of FeOOH are partially broken, which is rooted in the Co incorporation, thus resulting in unsaturated FeO6 ligand structures and a relatively narrow bandgap. Consequently, the reorganized Fe sites on the surface show an enhanced capability for adsorbing OH- species and the Co-FeOOH exhibits an improved conductivity. As expected, the Co-FeOOH/CFP hybrids exhibit an extremely low overpotential of approximate to 250 mV at 10 mA cm(-2) and a small Tafel slope, which far outperforms that of electrochemically sluggish FeOOH. The present work emphasizes the importance of local Fe coordination in catalysis and provides an in-depth insight into the mechanism of the enhanced catalytic activity.