One-pot photoassisted synthesis, in situ photocatalytic testing for hydrogen generation and the mechanism of binary nitrogen and copper promoted titanium dioxide

For the sustainable production of hydrogen by photocatalysis, the use of renewable resources such as water, organic compounds from plant biomass and earth abundant metal promoters is desired. We herein describe the previously not reported “one-pot” photoassisted synthesis of a binary metal–nitrogen promoted Cu(0)–N-TiO2 photocatalyst from a N-TiO2 precursor by photodeposition of copper directly in the photocatalytic suspension. The N-TiO2 contains nanocrystalline anatase as found by XRD and Raman spectroscopy. X-ray Photoelectron Spectroscopy (XPS) and Electron Spin Resonance (ESR) spectroscopy indicate that a nitrogen promoter is present as a substitutional site. The scheme of relaxation of a photoexcited charge through a substitutional nitrogen induced midgap states in N-TiO2 is proposed. The binary promoted Cu(0)–N-TiO2 photocatalyst prepared from N-TiO2 by “one-pot” photodeposition of copper in the suspension showed a high activity in the in situ hydrogen generation under near-UV/visible light with glycerol in water, up to 675 μmol g−1 h−1. The “one-pot” photoassisted synthesis and mechanism of operation of the Cu(0)–N-TiO2 photocatalyst are studied by the complementary in situ spectroscopic methods.