Embedding Amorphous Molybdenum Sulfide within a Porous Poly(3,4-ethylenedioxythiophene) Matrix to Enhance its H2 -evolving Catalytic Activity and Robustness.

Amorphous molybdenum sulfide (MoSx ) is a promising alternative to Pt catalyst for the H2 evolution in water. However, it is suffered of an electrochemical corrosion. In this report, we present a strategy to tack this issue by embedding the MoSx catalyst within a porous poly(3,4-ethylenedioxythiophene) (PEDOT) matrix. The PEDOT host is firstly grown onto a fluorine-doped tin oxide (FTO) electrode by electrochemical polymerization of EDOT monomer in an acetonitrile solution to perform a porous structure. The MoSx catalyst is subsequently deposited onto the PEDOT by an electrochemical oxidation of [MoS4 ]2- monomer. In a 0.5 M H2 SO4 electrolyte solution, the MoSx /PEDOT shows higher H2 -evolving catalytic activities (current density of 34.2 mA/cm2 at -0.4 V vs RHE) in comparison to a pristine MoSx grown on a planar FTO electrode having similar catalyst loading (24.2 mA/cm2 ). The PEDOT matrix contributes to enhance the stability of MoSx catalyst by a significant manner. As such, the MoSx /PEDOT retains 81 % of its best catalytic activity after 1000 potential scans from 0 to -0.4 V vs. RHE, whereas a planar MoSx catalyst is completely degraded after about 240 potential scans, due to its complete corrosion.