Interfacial engineering of lattice coherency at ZnO-ZnS photocatalytic heterojunctions

Abstract

Heterogeneous semiconductor interfaces with built-in electric fields are central to promoting directional carrier migration and separation for charge-induced redox reactions. Unfortunately, most heterointerfaces are structurally incoherent due to large lattice mismatch accompanied with multiple dangling bonds, imposing high energy barriers for charge transport. Here, we report the atomic engineering of ZnO-ZnS heterogeneous interfaces, transforming from incoherent characters to semi-coherent counterparts through annealing-induced spontaneous assembly of ZnS nanoparticles on single-crystalline ZnO nanowires, which is substantiated by aberration-corrected scanning transmission electron microscopy. Theoretical calculations reveal that semi-coherent interfaces are beneficial in annihilating deep local gap states and thus, remarkably reducing carrier transport barrier height by 1.25 eV. This contributes to a 5.8-fold enhanced photocatalytic hydrogen production rate with an improved stability. The study provides physical insights into interfacial lattice engineering of photocatalytic heterojunctions and offers a convenient strategy to convert incoherent interfaces to photocatalytically favorable semi-coherent phase boundaries for solar energy utilization.