[MoO(S₂)₂L]^1- (L = picolinate or pyrimidine-2-carboxylate) Complexes as MoS_x-Inspired Electrocatalysts for Hydrogen...

Crystalline and amorphous molybdenum sulfide (Mo-S) catalysts are leaders as 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. Herein is presented two water-soluble Mo-S complexes based around the [MoO(S₂)₂L₂]^1- motif. We present ¹H NMR spectra that reveal (NEt₄)[MoO(S₂)₂picolinate] (Mo-pic) is stable in a d₆-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.