[Mo₃S₁₃]²⁻ Cluster Decorated Sulfur‐doped Reduced Graphene Oxide as Noble Metal‐Free Catalyst for Hydrogen Evolution Reaction in Polymer Electrolyte Membrane Electrolyzers

Abstract

Non‐noble metal catalysts represent a central direction of seminal scientific research in electrocatalysis due to the high cost and scarcity of present Pt‐based catalysts for the hydrogen evolution reaction (HER) in particular. Here, we develop a novel hybrid material of [Mo3S13]2− clusters decorated sulfur doped reduced graphene oxide (Mo3S13‐SrGO) as a HER catalyst for water electrolyzers. Doped S elements act as anchor points for [Mo3S13]2− cluster attachment via forming doped S−Mo coordinate bonds, which increase stability of the hybrid catalyst as well as contribute additional active sites for the HER. SrGO supports substantially enhance the activity of the hybrid catalyst, maintaining high catalyst utilization at high loading. In standard electrochemical tests, the Mo3S13‐SrGO catalyst exhibits a Tafel slope of about 40 mV per decade and a current density of 10 mA cm−2 at 174 mV overpotential, which are significantly better than those exhibited by unsupported [Mo3S13]2− clusters with a Tafel slope of 53 mV per decade and an overpotential of 244 mV at 10 mA cm−2. Further, the hybrid catalyst exhibits a good working stability in acidic media. In the form of nanostructured powder, Mo3S13‐SrGO can be readily processed into porous electrodes for practical applications using standard manufacturing technologies.

Fabrication of a Robust PEM Water Electrolyzer Based on Non‐Noble Metal Cathode Catalyst: [Mo3S13]2− Clusters Anchored to N‐Doped Carbon Nanotubes

“…The two spectra contain peaks at 531.0, 413.0, 395.0, 284.0, 229.0, and 163.0 eV, related to the characteristic binding energies of O1s, Mo3p 1/2 , Mo3p 3/2 , the overlapping Mo3d‐S2s, and S2p, respectively. [ 30,31 ] However, the C1s peak of Mo 3 S 13 ‐NCNT has a significantly higher relative intensity compared to that of freestanding [Mo 3 S 13 ] 2− due to the presence of NCNTs in the hybrids. The S/Mo ratios are 4.33 and 3.9 for [Mo 3 S 13 ] 2− and Mo 3 S 13 ‐NCNT hybrid, respectively.…”

“…Further information regarding elemental compositions of the two materials are presented in Tables S1 and S2 in the Supporting Information, which are consistent with our previous work. [ 30 ]…”

Non-Precious Metal Graphene-Based Catalysts for Hydrogen Evolution Reaction

“…Additionally, Figure 7 reveals that iron-doped tungsten oxide nanoplate supported on rGO nanocomposite (Fe-WOxP/rGO) exhibited excellent electrocatalytic activity toward HER due to the coupled synergic effect between the formation of many oxygen vacancies on tungsten oxide in the nanoplate structure of Fe-WOxP and rGO nanosheet [37]. Furthermore, a novel hybrid material of [Mo 3 S 13 ] 2clusters supported on sulfur doped rGO (S-rGO) with outstanding catalytic performance toward the HER has been reported [38]. Figure 8 depicts significant improvements in HER activity compared to four hybrid catalysts to simple [Mo 3 S 13 ] 2− clusters.…”

“…Figure 8 depicts significant improvements in HER activity compared to four hybrid catalysts to simple [Mo 3 S 13 ] 2− clusters. The last was attributed to the S-rGO support that provides properties such as high electrical conductivity, elevated porosity, an increase in the electrochemical active surface area, facilitates the mass transport, and decreases the value of the Tafel slope [38].…”

“…conductivity, elevated porosity, an increase in the electrochemical active surface area, facilitates the mass transport, and decreases the value of the Tafel slope [38]. Furthermore, a reduced graphene oxide/metallic MoSe2:Cu nanosheet has been synthesized and shown to be effective toward the HER as the Cu doping and the interface effect between MoSe2 and rGO increased the electrical conductivity of the material, resulting in an active and stable catalyst [39].…”