In situ construction of Fe(Co)OOH through ultra-fast electrochemical activation as real catalytic species for enhanced water oxidation

Abstract

Oxygen evolution reaction (OER) as the anodic reaction of water splitting is of great significance to the development of hydrogen energy and fuel cell. Although transition metal hydr(oxy)oxides (M-OOH) have satisfactory intrinsic catalytic activity as real catalytic species for OER, their poor dispersion and stability and complicated preparation way seriously limit their subsequent applications. Herein, using a special Co-MOF precursor, a kind of bimetallic hydroxyl oxides (Fe(Co)OOH) has been in situ constructed through a one-step rapid electrochemical activation. Combining electrochemical tests with in situ spectroscopic methods, we demonstrated that the rich electronic CoBDC (Co2(OH)2(C8H4O4)) array structure is conducive to the regulation of electronic structure and the enrichment and transference of OH* species to stabilize M-OOH species and exert bimetal synergistic effect. As expected, Fe(Co)OOH@CoBDC-NF (FCCN) shows the optimal OER performance, with an overpotential of only 241 mV at 100 mA cm−2, which was nearly 30% lower than reported RuO2. Meanwhile, thanks to the support and dispersion of Co-MOF precursor, its performance can remain after 240 h of ultra-long stability test and large current test under strong alkali condition. In general, this work provides a new design inspiration for ultra-fast synthesis of bimetallic hydroxyl oxides with good dispersion, high activity and long-term stability.