First-principles calculations of 0D/2D GQDs-MoS mixed van der Waals heterojunctions for photocatalysis: a transition from type I to type II.

The fabrication of type II heterojunctions is an efficient strategy to facilitate charge separation in photocatalysis. Here, mixed dimensional 0D/2D van der Waals (vdW) heterostructures (graphene quantum dots (GQDs)-MoS) for generating hydrogen from water splitting are investigated based on density functional theory (DFT). The electronic and photocatalytic properties of three heterostructures, namely, CH-MoS, CH-MoS and CH-MoS are estimated by analyzing the density of states, charge density difference, work function, Bader charge, absorption spectra and band alignment.