Crystalline and amorphous molybdenum sulfide (Mo–S) catalysts are earth-abundant materials for electrocatalytic hydrogen production. The development of a molecular motif inspired by the Mo–S catalytic materials and their active sites is of interest, as molecular species possess a great degree of tunable electronic properties. Furthermore, these molecular mimics may be important for providing mechanistic insights toward the hydrogen evolution reaction (HER) with Mo–S electrocatalysts. In this talk, I will present some Mo–S complexes based around the [MoO(S2)L] motif, in which L is a bidentate ligand such as bpy. By varying the substitution on the bpy ligand, we demonstrate the induction effect on the S−S ligand, thereby tuning the rate constants for HER and overpotentials. Complexes based on L = picolinate or pyrimidine-2-carboxylate are also synthesized and investigated. (NEt4)[MoO(S2)2picolinate] (Mo-pic) is stable in a DMSO solution after heating at 100 °C, in air, revealing unprecedented thermal and aerobic stability of the homogeneous electrocatalyst. Both Mo-pic and (NEt4)[MoO(S2)2pyrimidine-2-carboxylate] (Mo-pym) are shown to be homogeneous electrocatalysts for the HER. The TOF of 27–34 s-1 and 42–48 s-1 for Mo-pic and Mo-pym and onset potentials of 240 mV and 175 mV for Mo-pic and Mo-pym, respectively, reveal these complexes as promising electrocatalysts for the HER. At the end, catalytic polymers based around the MoO(S2)2L catalytic motif to a well-defined poly-4-vinyl-pyridine (P4VP) polymer backbone (MoS-P4VP) will also be presented. By comparing catalytic performance metrics of MoS-P4VP to the monomeric complex, the P4VP backbone was revealed to bestow stability and superior catalytic performance as a heterogeneous catalyst.

Mo-S Complexes based on [MoO(S2)2] motif as MoSx-inspired electrocatalysts for hydrogen production

253rd National Meeting (2017)

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