2D molybdenum disulphide (2D-MoS2) modified electrodes explored towards the oxygen reduction reaction

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Two-dimensional molybdenum disulphide (2D-MoS2) nanosheets are recognized electrocatalysts, primarily for the Hydrogen Evolution Reaction (HER).
• The Oxygen Reduction Reaction (ORR) is crucial for fuel cell efficiency but less explored with 2D-MoS2, especially in acidic electrolytes.
• Conventional research often overlooks acidic conditions for 2D-MoS2 in ORR catalysis.

Purpose of the Study:

• To investigate the potential of 2D-MoS2 as an electrocatalyst for the ORR in acidic media (0.1 M H2SO4).
• To evaluate the influence of various carbon-based electrode substrates (BDD, EPPG, GC, SPE) and 2D-MoS2 mass on ORR performance.
• To provide insights into the ORR mechanism on 2D-MoS2 in acidic conditions.

Main Methods:

• Electrochemical evaluation of 2D-MoS2 modified electrodes (BDD, EPPG, GC, SPE) for ORR in 0.1 M H2SO4.
• Systematic variation of 2D-MoS2 loading/mass on different carbon supports.
• Analysis of ORR onset potential and reaction mechanism (2-electron vs. 4-electron pathway).

Main Results:

• Significant improvements in ORR activity were observed by optimizing 2D-MoS2 mass and selecting appropriate carbon supports.
• ORR onset potential was reduced to ca. +0.10 V on EPPG, GC, and SPEs with optimal 2D-MoS2 loading, approaching Pt performance (+0.46 V).
• This study demonstrates, for the first time, effective ORR catalysis by 2D-MoS2 on carbon substrates in acidic conditions.

Conclusions:

• Careful selection of carbon support materials and optimal 2D-MoS2 mass are critical for enhancing ORR activity in acidic fuel cells.
• 2D-MoS2 shows considerable promise as an ORR electrocatalyst in acidic environments, particularly on SPEs.
• The findings offer valuable guidance for designing and testing 2D-nanosheet electrocatalysts for ORR applications.