Stable and active CuxO/TiO2 nanostructured catalyst for proficient hydrogen production under solar light irradiation

• Biphasic TiO2 nanostructures were prepared by using hydrothermal and thermal treatment methods.
• Cu2O and Cu° interacted with TiO2 nanostructures govern the improved photocatalytic properties.
• Cu1.5TNT exhibited highest rate of H2 production using ethylene glycol as a hole scavenger.
• Copper species can act as both photosensitizer and co-catalyst under solar light irradiation.

The nanostructured TiO2 materials impregnated with Cu were prepared via a simple and eco-friendly preparation route. The materials are comprised of nano -tubes, -rods and -particles whose surfaces are modified by a fine dispersion of CuxO clusters (Cuo and Cu2O) as evidenced by TEM and XPS analysis. Structural and optical characterization ascertained the biphasic (anatase-rutile) crystal structure of TiO2 nano-objects. The presence of CuxO at the surface extends the absorption from the UV to the visible light range. In contrast to the pristine and calcined TiO2 nanotubes (TNT), the CuxO/TiO2 nanostructures (Cu1.5TNT) exhibit a prolonged life-time of photogenerated charge carriers and decreased surface area as confirmed by the photoluminescence spectra and surface area analysis, respectively. The prepared photocatalysts were tested for hydrogen (H2) production activity using water, mono and di-hydroxylic alcohols solutions under solar light irradiation. Surprisingly, Cu-modified TiO2 nanostructures (Cu1.5TNT) have shown an unusually high rate of H2 production of about 114.9±2 mmol h−1 g−1cat under a set of optimized experimental conditions. Among all of the studied photocatalysts, the Cu1.5TNT catalyst exhibits enhancements of 33 and 18 fold in the H2 production rate as compared to the commercial TiO2 nanoparticles (TNP) and calcined TNT, respectively. We report here on the highest known rate of H2 production using the nanostructured Cu-doped TiO2 photocatalyst (Cu1.5TNT) under solar light irradiation. This unprecedented H2 production is attributed to synergistic effects of nanocrystalline structures, morphology and copper oxide species (Cuo and Cu2O) present in the photocatalyst.

Unprecedented hydrogen gas of 114.9±2 mmol h−1 g−1cat produced by using CuxO/TiO2 nanostructured photocatalysts in aqueous ethylene glycol solution under solar irradiation. The high activity is ascribed to the presence of both Cuo and Cu2O in nanocomposite and synergistic effects of TiO2 nanocrystalline structure, mixed morphologies of nanotube, nanorods and nanoparticles for the better surface-interfce properties.Figure optionsDownload as PowerPoint slide