Modulation of interfacial charge transfer by self-assembly of single-layer graphene enwrapped one-dimensional semiconductors toward photoredox catalysis

Abstract

A progressive layer-by-layer self-assembly strategy has been developed to construct a graphene-wrapped and WO ₃ nanorods-coupled TiO ₂ nanobelts photocatalyst, in which a highly efficient cascade electron transfer pathway was judiciously built.

Abstract

In recent years, the exquisite modulation of the transport of photogenerated electron–hole charge carriers has constituted a long-standing challenge. To this end, herein, a spatially hierarchical single-layer graphene (GR)–wrapped and WO ₃ nanorods (NRs)–coupled TiO ₂ nanobelts (TNBs) ternary nano-architecture (TNBs/WO ₃ NRs/GR), as a conceptual platform, has been progressively designed via a facile and green layer-by-layer assembly strategy based on pronounced electrostatic interaction. It was remarkable to find that the interfacial charge transfer of a TNBs/WO ₃ NRs/GR ternary heterostructure can be finely modulated by interfacial architectural engineering, thus contributing to its significantly improved photoredox performance, including photocatalytic oxidation of organic pollutants and reduction of heavy metal ions, in comparison with single and binary counterparts. The construction of highly efficient cascade electron transfer pathways at the interface is responsible for the enhancement in photoactivities of a ternary heterostructure, which is afforded by intimately intercalating WO ₃ NRs in the interfacial domains of TNBs and GR. In this unique ternary nano-architecture, the WO ₃ NRs ingredient serves as an efficient interfacial charge transfer mediator and GR serves as an electron transporter and collector to conspicuously trigger a cascade electron relay from TNBs to GR, thereby expediting the efficacious charge transfer, prolonging the lifetime of photogenerated electron–hole pairs, and resulting in the significantly enhanced photoredox activities of the TNBs/WO ₃ NRs/GR heterostructure. In addition, the predominant active species responsible for the photoredox process were determined and the underlying photocatalytic mechanism was delineated.