An ambient temperature, CO 2 -assisted solution processing of amorphous cobalt sulfide in a thiol/amine based quasi-ionic liquid for oxygen evolution catalysis.

We report the synthesis of CoS _x nanosheets from a 1,2-ethanedithiol/n-butylamine quasi-ionic liquid with the assistance of compressed CO ₂ at ambient temperature. The CoS _x achieves a current density of 10 mA cm ^-2 at an overpotential of 271 mV for the oxygen evolution reaction. Furthermore, our method is applicable to the fabrication of other transition metal chalcogenides.