Highly efficient and stable Cu2O–TiO2 intermediate photocatalytic water splitting

Abstract Cu2O is considered to be an excellent photocatalytic material because of its narrow band gap (Eg = 2.17 eV), non-toxicity and low cost. However, it is not stable due to its serious photocorrosion. Here, we report Cu2O-doped TiO2 nanoparticles with significant catalytic activity and stability. The as-prepared Cu-doped TiO2 will be self-reduced to Cu2O–TiO2 under light conditions. Furthermore, the Cu2O–TiO2 material exhibits extraordinary catalytic activity compared with common Cu–TiO2 materials. It exhibits a H2 evolution rate (16.25 mmol h−1 g−1) at about 100 times than that of pure TiO2. It can be found that its high catalytic activity depends on the TiO2 nanostructure and the attachment site of Cu atom. TiO2 nanoparticles with good dispersion structure exposed (101) facets and chemically absorb Cu to form an electron transfer channel, so that the reduced Cu2O can be continuously stable under illumination. From the results of density functional theory and experiments, it can be proved that reduced Cu2O narrows the bandgap of TiO2, which extends the optical absorption range of the material to 800 nm. And the effective charge transfer slackens the electron-hole recombination rate with the relevant electron lifetime increasing from 2.72 ns (0%-TiO2) to 7.92 ns (2%-TiO2). Because of its low cost, good stability and high catalytic efficiency, we believe it will bring the possibility of large-scale application.