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

Abstract

It is of increasing interest and an important challenge to develop highly efficient less-expensive cathode catalysts for anion-exchange membrane fuel cells (AEMFCs). In this work, we have directly prepared a carbon-supported CoS nanocatalyst in a solvothermal route and investigated the effect of heat-treatment on electrocatalytic activity and long-term stability using rotating ring-disk electrode (RRDE). The results show that the heat-treatment below 400 °C under nitrogen atmosphere significantly enhanced the electrocatalytic performance of CoS catalyst as a function of annealed temperature in terms of the cathodic current density, the half-wave potential, the HO2 − product and the number of electrons transferred. The CoS catalyst that annealed at 400 °C (CoS-400) has exhibited a promising performance with the half-wave potential of 0.71 V vs. RHE (the highest one for non-precious metal chalcogenides), the minimum HO2 − product of 4.3% at 0.60 V vs. RHE and close to the 4-electron pathway during the oxygen reduction reaction in 0.1 M KOH. Also, the CoS-400 catalyst has comparable durability to the Pt/C catalyst.

Electrocatalysis in Fuel Cells

“…Non-noble metal oxides and chalcogenides are also promising catalysts for ORR. Some interesting works on the synthesis and evaluation of Ti-Nb oxides [15], CoS [16] and FeSe2 [17] were also included in this Special Issue.…”

Template-Assisted Synthesis of Nickel Sulfide Nanowires: Tuning the Compositions for Supercapacitors with Improved Electrochemical Stability

“…Transition metal sulfides, such as FeS, CoS, and ZnS, have gained intensive interest as semiconductor functional materials owning to their excellent properties and wide applications in energy storage and conversion, catalysts, and sensors. − In particular, nickel sulfides with various compositions and phases (Ni 3 S 2 , α-NiS, β-NiS, and NiS 2 ) have received considerable attention due to their promising applications in practical devices. , Since the first report of NiS as an electrode for supercapacitors by Hou et al, numerous researches have been conducted to probe the electrochemical performance of nickel sulfides. − It is noted that the poor electrical conductivity of nickel sulfides, like that of other sulfides and oxides, seriously inhibits the fast electron transport required for electrochemical stability at high current density and thereby hinders their practical application in energy storage devices . To overcome this drawback, considerable efforts have been devoted recently to explore effective strategies, including fabrication of novel nanostructures (e.g., nanotubes, nanosheets, , and hollow nanostructures , ) and hybridization with conductive materials (e.g., carbon nanotube, graphene , ).…”