Unveiling the photocatalytic water splitting over metal-free g-CN/γ-BNyne heterostructures using non-adiabatic molecular dynamics

Abstract

We herein computationally designed a metal-free graphitic carbon nitride/γ-boron nitride (g-CN/γ-BNyne) heterostructure as a promising photocatalyst for overall water splitting and sustainable hydrogen fuel production. The heterostructure shows type-II band energy alignment and significant optical absorption in UV and near-visible regions. The studies on excited state dynamics show that the low nonadiabatic coupling between the VBM and CBM in the heterostructure and the faster decoherence time (22.28 fs) extend the electron–hole (e–h) recombination time to 261.52 ps, giving enough time for the photogenerated carriers to take part in redox reactions. The boron atoms of the γ-BNyne surface act as Lewis acid sites, which effectively trap water molecules, resulting in the consequent oxygen evolution, and simultaneously the g-CN surface also promotes the hydrogen evolution reaction. Thus, this work presents a design for a potential metal-free type-II photocatalyst for carrying out both oxygen and hydrogen evolution reactions simultaneously.