Effect of Ligand Coverage on Hydrogen Evolution Catalyzed by Colloidal WSe2

Abstract

In this work, we examine the direct influence of ligand coverage on a catalytically active surface for the hydrogen evolution reaction (HER). We tested the electrochemical and electrocatalytic properties of colloidally synthesized WSe2 with dodecylamine ligands before and after treatment with Meerwein’s reagent, which was shown to reduce the coverage of amine and lead to an improvement in the overpotential for HER by as much as 180 mV on the same electrode (reversible upon re-ligation with amine). The underlying mechanism of the improvement in HER catalysis following treatment with Meerwein’s reagent was investigated using a combination of Tafel slope analysis, electrochemically active surface area measurements, and impedance spectroscopy. These electrochemical measurements are rationalized with Fermi level and d-band center analysis from XPS. Together, these measurements suggest that, while the surface area of the WSe2 increases upon ligand stripping, the intrinsic catalytic capability of the WSe2 also c...