Amorphous Fe/Co-based tannic acid salts as robust oxygen evolution pre-catalysts

Abstract

Improving the slow kinetics of the alkaline oxygen evolution reaction is highly desirable for accelerating the commercialization of water electrolysis. Herein, amorphous Fe/Co-based tannic acid salts were synthesized by assembly of Fe³⁺, Co²⁺, and tannic acid, which are loaded on carbon nanotube surface forming a coaxial cable-like microstructure and act as a pre-catalyst for oxygen evolution. The pre-catalyst shows an excellent catalytic activity with a high TOF value of 0.949 s⁻¹ at an overpotential of 350 mV in 1 M KOH. The electrochemical test and careful characterization of the post-catalyst demonstrates that the superb performance comes from the in situ derived small sized oxyhydroxides loaded on the carbon nanotube surface. The amorphous feature of the tannic acid salt facilitates the re-construction and formation of oxyhydroxides. This study is expected to promote the fundamental understanding of oxygen evolution catalysis and shows some hints for the design of advanced electrocatalysts.