The critical role of intragap states in the energy transfer from gold nanoparticles to TiO2

Abstract

Cathodoluminescence spectroscopy is profitably exploited to study energy transfer mechanisms in Au and Pt/black TiO₂ heterostructures. While Pt nanoparticles absorb light in the UV region, Au nanoparticles absorb light by surface plasmon resonance and interband transitions, both of them occurring in the visible region. The intra-bandgap states (oxygen vacancies) of black TiO₂ play a key role in promoting both hot electron transfer and plasmonic resonant energy transfer from Au nanoparticles to the TiO₂ semiconductor with a consequent photocatalytic H₂ production increase. An innovative criterion is introduced for the design of plasmonic composites with increased efficiency under visible light.