Energy transfer from plasmonic gold nanoparticles to black-TiO2

The plasmonic interactions from the surface plasmon resonance (SPR) of metals to the semiconductor can occur by different mechanisms, such as: (i) hot electron transfer; (ii) thermally excited electron transfer; (iii) plasmonic resonant energy transfer (PRET) from metals to semiconductors. The deposition of metal NPs (Au and Pt) on TiO2 samples results in an enhancement of one order of magnitude in the rate of photocatalytic H2 production compared to that measured for bare oxides. Interestingly, for both supports the deposition of Au NPs led to higher H2 production rates compared to Pt and the hydrogen production rates follow the order Au/Black TiO2 > Pt/Black TiO2 >> Black TiO2. Cathodoluminescence spectroscopy revealed to be a unique tool to study the plasmonic interactions between Au nanoparticles and core-shell and highly defective black Tio2 nanocrystals In the case of P25 TiO2, investigated as a reference material, both hot electron transfer and PRET can play a significant role in boosting the H2 production rate. Differently, in the case of black TiO2, PRET only is responsible for the enhancement of the TiO2 production rate. The selective plasmonic resonant energy transfer from Au nanoparticles to electronic levels of TiO2 related to oxygen vacancies represents an innovative criterion that can be exploited for the design of plasmonic composites with enhanced visible light photoresponse.