Mesoporous assembled structures of Cu2O and TiO2 nanoparticles for highly efficient photocatalytic hydrogen generation from water

Photocatalytic water splitting to produce hydrogen using solar energy is a particularly attractive solution to increasing energy demands. However, to be of practical use, semiconductor electrodes need to be made of inexpensive, abundant elements and have a high, yet stable, photocatalytic H-2-production activity. Here we report the first demonstration of 3D mesoporous networks of Cu2O and TiO2 nanoparticles as highly efficient photocatalysts for hydrogen generation from water. These assembled structures feature a highly accessible pore surface that exposes a large fraction of anatase TiO2 and Cu2O nanoparticles to electrolytes, and has a small grain size of the constituent nanocrystals, which lead to excellent activity for H-2 evolution via a UV-visible light-driven reduction of protons. Catalytic results associated with optical UV-vis/NIR absorption and photoluminescence (PL) data indicated that the large separation of photogenerated electrons and holes at the Cu2O-TiO2 p-n junctions was the main reason attributed to the improved photochemical performance. Consequently, the mesoporous Cu2O/TiO2 catalyst containing similar to 1.5 wt% Cu reaches an average H-2 evolution rate of similar to 542 mmol h(-1) (or similar to 36 133 mmol h(-1) g(-1)) with an apparent quantum efficiency (QE) of 13.5% at 365 nm and an incident photon conversion efficiency of similar to 4.1% under UV-visible light illumination (360-780 nm), which is one of the best HER activities among TiO2-based semiconductor systems reported to date.