Mixed-Phase 2D-MoS2 as an Effective Photocatalyst for Selective Aerobic Oxidative Coupling of Amines under Visible-Light Irradiation.

Abstract

Metal-semiconductor heterojunctions play a vital role in photocatalysis, yet their preparation can be exceedingly difficult. The heterojunction helps not only to separate the charges and inhibit recombination processes but also to transfer the photogenerated electron/hole to the reacting molecule. Here, we demonstrate 1T (metallic)-2H (semiconducting) phase boundaries intrinsic to individual sheets of chemically exfoliated 2D-MoS2 can serve as heterojunctions for enhanced photocatalysis in comparison to only semiconducting phase. Due to the abundance of heterojunctions in these multiphasic materials, chemically exfoliated 2D-MoS2 provides improved stability and transfer of photogenerated charges to the reactants, giving better yield. We demonstrate that this easy to synthesize material is an effective photocatalyst for the aerobic oxidative coupling of amines to imines under visible light irradiation. Given its broad applications, we believe mixed phase 2D-MoS2 can be of interest to several industrial synthetic applications related to semiconductor-based photocatalysis. As an added advantage, this heterogeneous photocatalyst can be recycled for several times up to five cycles without any significant loss in the activity.