Carbon‐Supported CoSe₂ Nanoparticles for Oxygen Reduction Reaction in Acid Medium

Abstract

Carbon‐supported CoSe2 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.‐% CoSe2/C nanoparticles were investigated by means of powder X‐ray diffraction (PXRD), differential thermal gravimetric analysis (DTA‐DTG) and rotating disc electrode (RDE) techniques. CoSe2 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 H2SO4. CoSe2/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 O2‐saturated 0.5 M H2SO4 at 25 °C. 20 wt.‐% CoSe2/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).

Iron and nickel doped CoSe2 as efficient non precious metal catalysts for oxygen reduction

“…Among them, cobalt based selenides (CoSex) are attracting enormous interest as new ORR electrocatalysts. For example, CoSe2/C obtained by Feng et al [5,6] showed superior electrocatalytic activity towards ORR with an open circuitry potential of 0.81 V in 0.5 M H2SO4, and higher methanol tolerance than that of Pt/C. Susac et al [7] exhibited that cobalt-selenium (Co-Se) with varying content of Se obtained by magnetron sputtering and chemical methods indicated a electrocatalytic activity towards ORR in an acidic electrolyte.…”

What Can We Learn in Electrocatalysis, from Nanoparticulated Precious and/or Non-Precious Catalytic Centers Interacting with Their Support?

“…Besides the ORR activity on the Co-Se system, the methanol tolerance was further investigated in alkaline medium [102]. Without surprise, the CoSe2 nanocatalyst performance in alkaline medium is better than that in acid medium revealing further that the carbon-supported cubic phase of CoSe2 is a promising non-precious electrocatalyst for alkaline fuel cells [103]. Furthermore, the oxygen reduction activity of 20 wt % CoSe2/C in 0.1 M KOH was slightly higher than that of Co3O4/rmGO (reduced mildly oxidized graphene oxide) and comparable to that of Co3O4/NrmGO (nitrogen-doped mildly oxidized graphene oxide) as reported by Liang et al [104].…”

Positive Effect of Heat Treatment on Carbon-Supported CoS Nanocatalysts for Oxygen Reduction Reaction

“…Recently, non-precious metal chalcogenides, e.g., MS2 {M = Fe [9], Co and (Co, Ni) [10]} thin film, CoS2 [11], CoSe2 [12,13], Co1−xS [14] nanoparticles have attracted extensive attention due to promising catalytic activity for ORR, low cost and abundant reserve in the earth's crust. In Ref.…”

“…In Ref. [13,14], one notes that heat treatment plays an important role to produce electrocatalysts with high performance. However, Dai and his coauthors did not explain the reason for annealing treatment in Ref.…”

“…These results suggest that this mild synthesis route is available for CoS nanoparticles when the S/Co molar ratio in the initial reaction solution is equal to 3.0. Furthermore, the thermal stability of the prepared CoS nanoparticles is below 450 °C, which is similar to that of CoSe2 nanoparticles [13], and lower than that of Co1−xS [14]. In this work, therefore, our following investigation will mainly concentrate on four samples: as-prepared, CoS-250, -300 and -400.…”