Ag sensitized TiO2 and NiFe2O4 three-component nanoheterostructures: synthesis, electronic structure and strongly enhanced visible light photocatalytic activity

Abstract

This study reports on the synthesis and characterisation of two- and three-component visible light active photocatalytic nanoparticle heterostructures, based on TiO₂ and NiFe₂O₄ and sensitized with Ag. We observe that a Ag content as small as 1 at% in the TiO₂/NiFe₂O₄ heterostructure increases by more than an order of magnitude the rate constant for the visible light photocatalytic process. We rationalise this in terms of the measured structure and electronic structure data of the binary and ternary combinations of the component materials and focus on details, which show that an optimised deposition sequence is vital for attaining high values of photocatalytic efficiency, because the charge transfer across the interfaces appears to be sensitive to where the Ag is loaded in the heterostructure. The overall higher visible light photocatalytic activity of the TiO₂/Ag/NiFe₂O₄ heterostructure was observed and is attributed to enhanced charge carrier separation efficiency and migration via vectorial electron transfer.