Insights into unidirectional migration of photo-excited electrons at ZnFe2O4/graphene van der Waals interface

Abstract

Constructing heterojunction based on the energy band step method takes on an effective solution to the high recombination rate of photo-generated carriers in single photocatalysts. Beyond binary/graphene (GR) systems, there is a rising trend of demand in multicomponent/graphene (MMO/GR) photocatalysts due to the unique opportunities offered by these composites. Towards rational design of MMO/GR-based photocatalysts, the evolution of electronic structure at ZnFe2O4/graphene (ZFO/GR) interface is carefully investigated by first-principles calculations within the framework of the density functional theory (DFT). We reveal that the bloom in photocatalytic activity of ZFO/GR mainly be attributed to the unidirectional flow of photo-excited electrons from ZFO to GR but affected by synergetic effects of surface states of ZFO and high electro-conductibility of GR. The general insights in this work not only clarify the nature of enhanced photocatalytic activity of ZFO/GR photocatalyst, but also expand and deepen the knowledge of MMO/GR composites, thus are allowed for the future rational design of MMO/GR-based energy conversion materials.