Size‐Dependent Enhancement of Electrocatalytic Oxygen‐Reduction and Hydrogen‐Evolution Performance of MoS₂ Particles

Abstract

MoS2 particles with different size distributions were prepared by simple ultrasonication of bulk MoS2 followed by gradient centrifugation. Relative to the inert microscale MoS2, nanoscale MoS2 showed significantly improved catalytic activity toward the oxygen-reduction reaction (ORR) and hydrogen-evolution reaction (HER). The decrease in particle size was accompanied by an increase in catalytic activity. Particles with a size of around 2 nm exhibited the best dual ORR and HER performance with a four-electron ORR process and an HER onset potential of -0.16 V versus the standard hydrogen electrode (SHE). This is the first investigation on the size-dependent effect of the ORR activity of MoS2, and a four-electron transfer route was found. The exposed abundant Mo edges of the MoS2 nanoparticles were proven to be responsible for the high ORR catalytic activity, whereas the origin of the improved HER activity of the nanoparticles was attributed to the plentiful exposed S edges. This newly discovered process provides a simple protocol to produce inexpensive highly active MoS2 catalysts that could easily be scaled up. Hence, it opens up possibilities for wide applications of MoS2 nanoparticles in the fields of energy conversion and storage.

Robust carbon dioxide reduction on molybdenum disulphide edges

“…Such layered assemblies offer a large number of edges (inset of Fig. 1b), which are believed to be highly electrocatalytically active sites in electrochemical reactions 17,23 . To further detail the atomic arrangement, scanning transmission electron microscopy (STEM) analysis was performed on several mechanically exfoliated, mono-and multi-layer-thick sheets of MoS 2 flakes.…”

“…In addition, the CO 2 reduction current density for MoS 2 is also significantly higher ARTICLE than the maximum current density (B8.0 mA cm À 2 ) achieved when Ag NPs were used in the dynamic electrochemical flow cell using a similar electrolyte solution 13 . For all the cases, the current densities were normalized against the geometrical surface area 9,10,[16][17][25][26] . Surprisingly, the MoS 2 catalyst also shows a high current density (50 mA cm À 2 ) in an Ar-saturated electrolyte, where only H 2 was detected as the major product (Supplementary Note 1 and Supplementary Fig.…”

“…MoS 2 became widely used as an efficient catalyst for hydrodesulphurization 15,16 , oxygen reduction reactions 17 and hydrogen evolution reaction (HER) 16,17 . Moreover, it was demonstrated that MoS 2 has a noteworthy performance for water splitting, approaching that of Pt-group metals [17][18][19] .…”

Origin of the catalytic activity of phosphorus doped MoS2 for oxygen reduction reaction (ORR) in alkaline solution: a theoretical study

“…Since the discovery of the ultrathin MoS 2 monolayer, the electro-catalytic property has attracted great attention 26–29 . It was reported that with the decrease of monolayer size, MoS 2 reveals favorable performance in ORR and hydrogen evolution reaction (HER) 29 .…”

MoS2 Decorated Carbon Nanofibers as Efficient and Durable Electrocatalyst for Hydrogen Evolution Reaction

“…The observed Tafel slope is among the best-reported slope for MoS2. For example, Tafel slopes of 87, 82 and 77 mV/decade were reported for defect-free MoS2 nanosheets, nanosized bulk MoS2 and MoS2 nanoparticles, respectively [42][43][44]. Lithium intercalated MoS2 showed a Tafel slope of 62 mV/decade [22].…”