Mo Thio and Oxo-Thio Molecular Complexes As Water-Soluble Self-Healing Catalysts for Photocatalytic Hydrogen Evolution on 2D Materials

Abstract

2D semiconducting nanosheets of Transition Metal Dichalcogenides are attractive materials for solar energy conversion because of their unique absorption properties. Recently, Hydrogen evolution reaction (HER) was achieved with thin 2D WSe2 nanosheets activated by well-known precious metal catalysts. Here, we propose for the first time, water-soluble, noble-metal-free, Mo thio- and oxo-thio-complexes anchored on 2D p-WSe2 nanosheets for efficient water splitting under visible light irradiation with photocurrent density up to 2.0 mA cm-2 at -0.2 V/NHE. These Mo thio and oxo-thio- molecular complexes represent an ideal class of catalysts, well-suited to functionalize 2D materials since they are stable in aqueous environments, cheap, environmentally benign to synthesize and process. We propose that the high performances of the oxo thio-Mo complexe catalysts arise from the strong adsorption on point defects of the 2D WSe2 substrate of Mo complexes such as (MoS4)2-, (MoOS3)2-, (Mo2S6O2)2- as shown from DFT calculations. More particularly, advantages of the water-soluble oxo-thio Mo complexes distributions, which spontaneously formed at well-defined pH are highlighted owing to their high electro-activity combined with their strong affinity toward point defects.