Molecular Simulation of Interfacial Chemistry of Oxygen and Water Molecules Within Defective Graphene/MoS₂...

The graphene/MoS₂ composite is a functional heterostructure with broad applications that leverage the synergistic properties of its constituents. Generally, small ambient molecules might penetrate and adsorb into the interlayer of graphene/MoS₂ and interact with surface defects, leading to chemical reactions within the confined spaces. Currently, the interfacial interaction and reaction mechanisms remain largely unclear. Herein, we employed density functional theory and ab initio molecular dynamics simulations to investigate the interfacial adsorptions and reactions of O₂ and H₂O molecules at the Graphene/MoS₂ interfaces with various vacancy types of MoS₂ surfaces. Various mechanisms and pathways have been identified for the thermodynamic trends and kinetic barriers in interlayer reactions. It is demonstrated that the pristine Graphene/MoS₂ is inert for molecular interlayer adsorption. However, there are obvious chemical reactions at the defect-involved G/MoS₂ interfaces. Specifically, the dissociation of molecular oxygen can induce surface oxidation, accompanied by the restoration of the electronic properties of graphene/MoS₂. The water molecule can undergo spontaneous dissociation at the defect sites, exhibiting enhanced activity for water splitting. As compared with bare MoS₂, the hybrid interfaces of graphene/MoS₂ can alter the chemical reactivities of adsorbed molecules. This work provides new insights into the interlayer chemistry for heterojunction interfaces.