Assembly of β-Cu2V2O7/WO3 heterostructured nanocomposites and the impact of their composition on structure and photoelectrochemical properties

Abstract

Multinary metal oxides and their heterostructures play a key role as light absorbers in the production of solar chemicals. Synthetic tunability is crucial to understand the impact of composition and structure on the photoelectrochemical performance. Here, we assemble β-Cu₂V₂O₇/WO₃ heterostructured nanocomposites using a novel seeded-growth approach which allows an unprecedented compositional tunability. A 10 fold increase in the net photocurrent density towards sulfite oxidation was measured for the nanocomposite with the lowest loading of WO₃ (β-Cu₂V₂O₇ : WO₃ = 1 : 0.1) as compared to the bare β-Cu₂V₂O₇ counterpart. This improvement is attributed to the formation of an intimate junction between the two metal oxides which favors charge transfer and separation. An increase in the WO₃ content results in the formation of macroscopic phase segregated domains which reduce these interfacial areas, thus degrading the phototoelectrochemical performance of the nanocomposites. While highlighting the effectiveness of heterostructuring and the importance of compositional tunability, this study points at the emerging need of techniques to control and to probe the intrinsic inhomogeneity of these complex inorganic heterojunctions.