Carbon‐Supported CoSe 2 Nanoparticles for Oxygen Reduction Reaction in Acid Medium

Carbon‐supported CoSe 2 nanoparticles, as non‐precious metal cathodic catalyst, were prepared via the in situ surfactant‐free method with the conventional heating. Structural and electrochemical properties of the obtained 20 wt.‐% CoSe 2 /C nanoparticles were investigated by means of powder X‐ray diffraction (PXRD), differential thermal gravimetric analysis (DTA‐DTG) and rotating disc electrode (RDE) techniques. CoSe 2 nanoparticles have two kinds of crystal structure after heat treatment under nitrogen at different temperature: orthorhombic at 250 and 300 °C; cubic at 400 and 430 °C. The latter structure has higher oxygen reduction activity than the former in 0.5 M H 2 SO 4 . CoSe 2 /C nanoparticles after heat treatment from 250 to 430 °C, have an onset potential from 0.78 to 0.81 V versus the reference hydrogen electrode (RHE) in O 2 ‐saturated 0.5 M H 2 SO 4 at 25 °C. 20 wt.‐% CoSe 2 /C nanoparticles, after heat treatment at 300 °C, promote ca. 3.5 electrons, per oxygen molecule, transferred during the oxygen reduction process. They have an oxidation wave centred at 0.96 V versus RHE and display higher methanol tolerance as compared to 20 wt.‐% Pt/C (E‐TEK).