Big pyridyl Schiff base π-conjugated skeleton based cobalt/iron metal complexes: bimetallic electrocatalysts for the oxygen evolution reaction

Abstract

Schiff base metal complexes exhibit huge potential as efficient electrocatalysts for the oxygen evolution reaction (OER). However, the high overpotential and complex synthesis process largely restrict their practical application. Herein, we report the design and synthesis of different cobalt/iron based redox active pyridyl Schiff base metal complexes by a one-pot method. Benefiting from the synergistic effect of Co and Fe in Co₃FePM-TPDA and the unique molecular structure, which provides favorable electron transportation and an abundance of active sites, the optimized Co₃FePM-TPDA electrodes exhibit an overpotential of 298 mV to reach 10 mA cm⁻² and significant stability in 1.0 M KOH. In addition, a minimal overpotential of 331 mV is sufficient to achieve 10 mA cm⁻² in simulated seawater electrolysis (1.0 M KOH + 0.5 M NaCl). Density functional theory (DFT) calculations indicate that the addition of Fe atoms improves the Gibbs free energy for adsorbed OOH on Co₃FePM-TPDA and improved catalytic activity for the OER process. The facile synthesis strategy presented in this work for effective and stable catalysts may expand the research on Schiff base metal complexes as OER catalysts.