Fe-doping effect on CoTe catalyst with greatly boosted intrinsic activity for electrochemical oxygen evolution reaction

Abstract

Fe-doping effect of Co-based catalyst was still not clear to the performance improvement of the oxygen evolution reaction (OER). Herein, Fe-doped CoTe was found very active for OER in water splitting reaction because of formation of the high valence state of Co species and lattice oxygen. The Fe-doping structure and surface chemical state were characterized by X-ray diffraction, transmission electron microscope and X-ray photoelectron spectroscopy; the electrocatalytic performances of oxygen evolution reaction were measured by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. An overpotential of 300 mV was required to drive the benchmark current density of 10 mA cm−2, reduced by 145 mV compared with the pristine CoTe catalyst, and the performance was also superior to the commercial IrO2 catalyst and some analogues catalysts. The intrinsic activity expressed by specific activity and turnover frequency was increased by 14 and 21 times at overpotential of 320 mV. High catalytic stability, kinetics and catalytic efficiency were also found on the Fe-doped CoTe catalyst. It was also very interesting to find that the excellent catalytic performance coming from the intrinsic properties of Fe doped CoTe via bimetallic synergy, not from the Fe impurity adsorbed from the electrolyte. Once this doped structure was formed, no further activation was required. The surface structure change induced by Fe doping with the formation of Co3+ and more lattice oxygen would contribute to the improved performance. The current work presented a simple and economical approach to promoting the catalytic performance of CoTe for OER and some novel contributions were offered for design and understanding the Fe-promoted Co-based catalyst for the water oxidation reaction.