The role of the defect on the adsorption and dissociation of water on graphitic carbon nitride

Abstract

Graphitic carbon nitride (g-C3N4) as a potential photocatalyst for the water splitting has the focus of numerous experimental and theoretical studies. In the process of water splitting, water/C3N4 interface plays the key role in the process, while the detailed mechanism, such as how water adsorbs and dissociates on the metal-free C3N4, is still unclear. Here how water interacts with the defect g-C3N4 was studied employed both density functional theory (DFT) and molecular dynamics calculations which show that water monomer, dimer, and clusters with three and four molecules at the defect site can form a stable coplanar structure with the g-C3N4 sheet. The clusters help to stabilize the adsorption at the defect site. Molecular dynamics simulations show that on the perfect g-C3N4 sheet water does not dissociate but on the defect g-C3N4 sheet do. There are two reoriented water layers near the g-C3N4 sheet because of the interaction between water and the g-C3N4 sheet. Our findings indicate that the defect within g-C3N4 plays a key role in the adsorption and dissociation of water.