Facile synthesis of Co-based selenides for oxygen reduction reaction in acidic medium

• Co-based selenides with different selenium contents were synthesized by a one-pot solvothermal method.
• The prepared Co-based selenides exhibited electrocatalytic activity towards ORR.
• Co-Se-75 displayed better ORR electrocatalytic activity with higher onset potential and a four-electron process.

Co-based selenides with different selenium contents were successfully synthesized by a one-pot solvothermal method. The physical properties of the prepared catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. While their electrocatalytic performances were evaluated by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The results showed that the Co-Se-75 displayed better electrocatalytic activity towards the oxygen reduction reaction with higher onset potential (0.708 V vs. RHE), reduction current (2.81 mA cm−2) and a four-electron oxygen reduction process. Furthermore, the catalyst exhibited better stability, stronger resistance to methanol, ethanol and ethlene glycol than that of the Pt/C (20 wt% Pt) catalyst.