ZIF67-derived Co–CoO@C nanocomposites as highly efficient and selective oxygen evolution reaction (OER) catalysts for seawater electrolysis

Oxygen evolution reaction (OER) in seawater is challenging due to the presence of multiple ions, specifically, chloride ions. Hence, development of catalysts that can efficiently and selectively catalyze OER while being resistant to the corrosive seawater environment is pivotal. Herein, a zeolitic imidazolate framework (ZIF67)-derived cobalt-cobalt oxide nanoparticles incorporated amorphous carbon (Co–CoO@C) nanocomposite is reported as an OER catalyst for seawater electrolysis. The nanocomposites obtained by different pyrolysis temperatures and atmospheres were meticulously compared for their OER activities. Graphite felt (GF) was used as the catalyst support to prevent corrosion associated with metal supports in seawater. The nanocomposite obtained at 600 °C in argon atmosphere (ZIF67-600Ar) exhibited remarkably low overpotential at 10 mA cm−2 (374 mV) in alkaline seawater owing to its high surface area, abundant active sites, hierarchical porosity, and optimal carbon, nitrogen, and cobalt content. The assembled ZIF67-600Ar/GF||Pt/C/GF cell exhibited overall voltage of ∼1.63 V at 20 mA cm−2 with a remarkable stability of ∼50 h (20 mA cm−2) in alkaline seawater. Post-OER studies were also performed to probe the origin of the OER activity.