(434d) Graphene Oxide Quantum Dots As Media for Hydrogen Generation from Photocatalytic Water Splitting

Graphene oxide (GO) derived from graphite oxidation is a semiconductor that can absorb light to generate electron-hole pairs for photocatalytic reactions. GO is suitable media for photocatalytic water splitting because it can be well dispersed in water. The electronic properties of GO can be tuned by varying its size and the embedded functionalities. As-received GO is a p-type semiconductor. Doping nitrogen on GO by ammonia treatment can convert GO to an n-type semiconductor. The size effect resulting from quantum confinement also influences the electronic structures of GO. Size modulation along with chemical modification represent a means to tune the electronic properties of GO for effective photocatalytic water splitting. We synthesized nitrogen-doped graphene oxide quantum dots (NGO-QDs) that exhibited promising water-reducing activities. Simultaneous presence of oxygen and nitrogen functionalities in single QDs might have eliminated defect states of the QDs to suppress charge recombination. The NGO-QDs had a band gap of approximately 2.3 eV. The Pt-deposited NGO-QDs effectively catalyzed H₂ evolution from an aqueous solution containing triethanolamine as a sacrificial electron donor. The quantum yield for H₂ evolution reached a value as high as 12 % under irradiation at 420 nm.