Oxygen Reduction Reaction Promoted by the Strong Coupling of MoS₂ and SnS

Abstract

Graphene-like molybdenum disulfide (MoS2) with unique catalytic features and chemical/electrochemical stability holds great potential as an oxygen reduction reaction (ORR) catalyst, but the overall weak oxygen adsorption and low electron conductivity limit its catalytic activity. Herein, MoS2 strongly coupled with an oxophilic SnS heterostructure embedded in nitrogen-doped porous carbon sheets (MoS2-SnS/NPC) was developed. The coupled SnS can not only tune the electronic structure but also promote the oxygen molecule adsorption and activation. Moreover, NPC can enhance the electron transfer as well as the structural stability of the MoS2-SnS heterostructure without agglomeration. As expected, MoS2-SnS/NPC exhibited enhanced catalytic activity that is superior to those of MoS2/NPC and SnS/NPC along with good catalytic stability for ORR. As a cathode catalyst, a homemade zinc–air battery driven by MoS2-SnS/NPC showed considerable discharging performance superior to the one driven by a commercial Pt/C catalyst in terms of open-circuit voltage, peak power density, and specific capacity. Furthermore, a MoS2-SnS/NPC-based zinc–air battery displayed a stable charging and discharging voltage gap for 48 h without an expanding trend, suggesting a robust cycling performance and heralding promising application prospects. The rotating ring-disk electrode and in situ electrochemical Raman tests revealed that the ORR underwent a combined 2-electron and 4-electron associative mechanism on MoS2-SnS/NPC, and the improved catalytic activity came from the synergistic effect of MoS2, SnS, S vacancy, and porous carbon sheets. This study provided a heterojunction strategy by coupling oxophilic SnS for boosting ORR electrocatalysis, which can be extended to other cheap transition-metal catalysts for efficient energy conversion.

A review of research progress and prospects of modified two-dimensional catalysts based on black phosphorus in the oxygen reduction reaction

“…which provides a feasible way to improve the ORR catalytic activity of MoS 2 . 25 Two dimensional molybdenum disulfide (2D MoS 2 ) is a promising electrocatalytic material, but most 2D MoS 2 has stagnated its development in the ORR caused by its low electron transfer properties and inert planes. In order to enhance the ORR performance of MoS 2 , improving the electron transfer rate and increasing the number of active sites are fundamental issues that need to be addressed.…”

“…However, embedding hydrophilic SnS into NPC can construct heterostructures, which provides a feasible way to improve the ORR catalytic activity of MoS 2 . 25…”

Recent advances in defect-engineered molybdenum sulfides for catalytic applications

“…, MoS 2 /graphene heterolayer), 237 MoS 2 with SnS ( e.g. , MoS 2 –SnS heterostructure), 238 and MoS 2 with Co 9 S 8 ( e.g. , Co 9 S 8 @MoS 2 core–shell heterostructure) 32 also show enhanced ORR/OER activity (see Table 10 for the comparison of catalytic performance of the defective MoS 2 materials), robust cycling stability, high power density, and improved cell voltage, due to the synergistic effect of the composition, interface, and defects.…”

“…236 The elevated performance is attributed to the synergy of the exposed edges of MoS 2 , highly active Mo-N coupling centers at the interface of N/ C and MoS 2 , N-induced activated carbon, improved electrical conductivity at the interface, and porous framework with diffusion channels. In addition, when employed as an air electrode, MoS 2 with graphene (e.g., MoS 2 /graphene heterolayer), 237 MoS 2 with SnS (e.g., MoS 2 -SnS heterostructure), 238 and MoS 2 with Co 9 S 8 (e.g., Co 9 S 8 @MoS 2 core-shell heterostructure) 32 also show enhanced ORR/OER activity (see Table 10 for the comparison of catalytic performance of the defective MoS 2 materials), robust cycling stability, high power density, and improved cell voltage, due to the synergistic effect of the composition, interface, and defects. It is also noteworthy that, echoing these success in metal-S and metal-O 2 /air batteries, defective MoS 2 is actively broadening its catalytic applications in fuel cells, 239 metal-CO 2 240,241 and other batteries, which also deserves attention.…”

Fe-Based Deep Eutectic Solvents for Amorphous Carbon-Encapsulated Fe3O4 Nanoparticles as Electrocatalysts for H2O2 Synthesis

“…Notably, the I D /I G value showed a decreasing trend from 0.3 to 0.2 V vs RHE and 0.1 to 0.0 V vs RHE and an increasing trend from 0.2 to 0.1 V vs RHE, suggesting reduction and oxidation processes due to the interaction between carbon defects and oxygencontaining intermediates. 68 Besides, no obvious peaks can be observed at no applied voltage and OCP, but a peak (at 590 cm −1 ) exists under 0.6 V vs RHE, belonging to a characteristic peak of Fe−O, and the peak intensity increases gradually and then weakens as the applied potential decreases (Figure 4g), 69,70 which may be caused by the adsorption and desorption of the oxygen species. In summary, it has been conjectured that the interface between ferric oxide and the carbon substrate may be the active site for two-electron oxygen reduction in Fe 3 O 4 @C.…”