Improving the Stability of Photodoped Metal Oxide Nanocrystals with Electrons Donating Graphene Quantum Dots

Doped metal oxide nanocrystals are emerging as versatile multi-functional materials with the potential to address several limitations of the current light-driven energy storage technology due to their unique ability to accumulate a large number of free electrons upon UV light exposure. The combination of these nanocrystals with properly designed holes collector could lead to steady-state electrons and holes accumulation thus disclosing the possibility for light-driven energy storage in a single set of nanomaterials. In this framework{,} it is important to understand the role of the hole collector during UV light exposure. Here we show{,} via optical absorbance measurements under UV light exposure{,} that well-defined graphene quantum dots with electron-donating character can act as hole acceptors and improve the stability of the photo-generated electrons in Sn-doped In2O3 nanocrystals. The results of this study offer new insight into the implementation of photo-charged storage devices based on hybrid organic/inorganic nanostructures.