Oxygen vacancy-enriched CoPi/TiO2 nanotubes/WO3 electrode for enhanced photoelectrochemical water oxidation

TiO 2 has been widely used in photocatalytic water splitting, but its wide band gap and easy recombination carrier limit its further application. In this work, highly ordered TiO 2 nanotube arrays (TiO 2 NBs) were prepared by anodic oxidation, and more oxygen vacancies were provided by local amorphous. The increase of oxygen vacancy improves the carrier separation efficiency, and the array structure achieves faster electron transport. In addition, WO 3 semiconductor was coupled with TiO 2 to construct heterojunction, expand the range of light absorption, and enhance the electron–hole pair separation efficiency. In addition, by introducing co-catalyst CoPi, the active site of the reaction was increased, and the catalytic reaction efficiency was improved kinetically. The results show that the photocurrent of CoPi/WO 3 /TiO 2 NBs is 10.2 μ A/cm 2 , which is 1.68 times that of TiO 2 NBs.