Oxygen Electroreduction on CoSe2 Nanoparticles Prepared via Hydrothermal Method in Acidic Medium

CoSe2 nanoparticles were synthesized via a facile hydrothermal method, and characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The synthesized CoSe2 was composed of crystalline orthorhombic phase and displayed a morphology of short and thin nanobelts. The results of the catalyst experiment demonstrate that the CoSe2 nanocrystals show high catalytic activity and methanol tolerance in oxygen reduction reaction(ORR) with an open circuit potential(OCP) of 0.80 V(vs. NHE) in 0.5 mol/L H2SO4 at 25 degrees C. The transfer process of about 3.7 electrons per oxygen molecule was determined during the reduction process and the transfer coefficient and Tafel slope were 0.50 and 118 mV, respectively, in the potential region of 0.64-0.75 V(vs. NHE). The high catalytic activity might be related to the high crystallization of the CoSe2 powder and the modification of selenium on the cobalt element.