Mechanism of interface modulation of g-C3N4/β-ZrNBr S-type heterojunction to enhance photocatalytic performance

Creating heterojunctions by combining two-dimensional (2D) materials is an efficient strategy for enhancing photocatalytic efficiency. In this work, the density functional theory was employed to model a van der Waals heterojunction consisting of a monolayer of g-C3N4 and a monolayer of β-ZrNBr. The electronic band configurations, carrier mobility, and catalytic capabilities of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) were investigated. The impact of biaxial strain on the band edge positions and structural band formations of the g-C3N4/β-ZrNBr heterojunction was also studied. The effective mass of electrons (me*/mo = 0.571) and holes (mh*/mo = −2.667) in the g-C3N4/β-ZrNBr heterojunction is lower than that of a monolayer of g-C3N4 (me*/mo = 1.995, mh*/mo = −2.964). It is predicted that the g-C3N4/β-ZrNBr heterojunction has a higher carrier mobility than a monolayer of g-C3N4. For the HER, the g-C3N4/β-ZrNBr heterojunction has a lowest Gibbs free energy (ΔGH*), only 0.081 eV under neutral conditions. For the OER, the g-C3N4/β-ZrNBr heterojunction can undergo spontaneous reactions under neutral conditions. This study provides a theoretical basis for the preparation of a novel g-C3N4/β-ZrNBr heterojunction photocatalytic material and serves as a reference for photocatalytic water splitting and other photoelectric applications.