Balancing the Hydrogen Evolution Reaction, Surface Energetics, and Stability of Metallic MoS Nanosheets via Covalent Functionalization.

We modify the fundamental electronic properties of metallic (1T phase) nanosheets of molybdenum disulfide (MoS) through covalent chemical functionalization, and thereby directly influence the kinetics of the hydrogen evolution reaction (HER), surface energetics, and stability. Chemically exfoliated, metallic MoS nanosheets are functionalized with organic phenyl rings containing electron donating or withdrawing groups. We find that MoS functionalized with the most electron donating functional group (p-(CHCH)NPh-MoS) is the most efficient catalyst for HER in this series, with initial activity that is slightly worse compared to the pristine metallic phase of MoS.