Effect of Se in Co-based selenides towards oxygen reduction electrocatalytic activity

Abstract

In this study, Co-based selenides with various selenium contents have been synthesized by heating dodecacarbonyltetracobalt [Co4(CO)12] and elemental selenium in 1,6-hexanediol solvent under refluxing conditions. The synthesized catalyst powders are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The samples exhibit cauliflower-like surface morphologies and reveal the crystalline characteristics of orthorhombic CoSe2 compound. Electrocatalytic performances of the Co–Se compounds for the oxygen reduction reaction in 0.5M H2SO4 electrolyte are evaluated by rotating disk electrode (RDE). Co–Se catalysts are electrochemical stable in the potential range of 0.05–0.80V (vs. NHE). The catalytic activity changes with increasing selenium content, and the highest activity is obtained at 67.1mol% Se in the catalyst, which can be attributed to the modification of selenium element on the electronic structure of cobalt.