Production of MoS2/CoSe2 hybrids and their performance as oxygen reduction reaction catalysts

A series of MoS2/CoSe2 hybrids with different weight ratios of MoS2 and CoSe2 were prepared by two different hydrothermal methods. The synthesized MoS2/CoSe2 hybrids were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrochemical activity and durability of MoS2/CoSe2 hybrids towards oxygen reduction reaction were studied in 0.5 M H2SO4 using rotating disk electrode. The results showed that all of them demonstrated catalytic activity towards oxygen reduction reaction. Furthermore, loading 30% MoS2 on CoSe2 by the first method (CoSe2-30a) displayed the best electrocatalytic activity. The onset potential (0.741 V vs. RHE) and half-wave potential (0.570 V vs. RHE) were higher than those of loading 20% MoS2 on CoSe2 by the second method (CoSe2-20b, 0.737 and 0.565 V vs. RHE), CoSe2 (0.708 and 0.560 V vs. RHE), and MoS2 (0.698 and 0.429 V vs. RHE). Most important, CoSe2-30a showed superior stability and better methanol tolerance than CoSe2-20b, CoSe2, and MoS2.