Boosting excitons dissociation in anion and cation co-doped polymeric semiconductor for selective oxidation reaction

Abstract

The inherent low dielectric properties and weak shielding effect of polymeric semiconductors result in excitons dominating their photoexcitation process, which greatly restricts the charge carriers mediated photocatalytic performances. Here, an anion and cation co-doping strategy was proposed to weaken the binding energy of excitons by forming distinguished positive and negative charge regions, where the charge asymmetry will give birth to an external potential to drive exciton dissociation. By taking polymeric carbon nitride as a typical model framework, we show that the incorporation of anion (Cl-, Br-, I-) and cation (Na+, K+) ions could create a significant spatial separation of electrons and holes, thereby promoting exciton dissociation. In detail, K+ and Cl- co-doped polymeric carbon nitride could effectively promote the dissociation of exciton into hot carriers, contributing to outstanding efficiency in hot-electron-involved photocatalytic processes such as superoxide radicals (O2•-) generation and phenyl boric acid oxidation under visible-light. This work presents a practical approach for promoting excitons dissociation by charge asymmetry introduction.