Modulating the Structure and Hydrogen Evolution Reactivity of Metal Chalcogenide Complexes through Ligand Exchange onto Colloidal Au Nanoparticles

The interaction between catalyst and support is well known to influence the reactivity and stability of heterogeneous catalysts, and electrochemical hydrogen evolution catalysts based on amorphous or nanocluster MoSx have shown enhanced reactivity when supported on Au disk electrodes. However, it has been synthetically challenging to create strong interactions between the MoSx catalyst layer and the metallic support material while maintaining high surface area and solution dispersibility for the composite catalyst. In this work, we utilize colloidal ligand-exchange methods to adsorb a single layer of tetrathiometallate complex (MoS42–, WS42–) onto colloidal Au nanoparticles and characterize the influence of the Au support on the electronic and geometric properties of the surface MSx monolayer. Utilizing spectroscopic and computational methods, we show that the Au surface templates cross-linked oligomers of MoSx to generate highly active bridging disulfide moieties and tunes the hydrogen atom binding energies through strong covalent Au–S interactions. These Au@MoS4 nanoparticles are easily incorporated into high surface area electrodes and are able to achieve 100 mA/cm2 of hydrogen evolution current density at 171 mV of overpotential.