Facile fabrication of pseudo-microspherical ZnO/CdS core-shell photocatalysts for solar hydrogen production by water splitting

Photocatalytic hydrogen production attracts great attention due to its clean energy conversion and renewable usage. In order to achieve efficient charge separations in photocatalysts, pseudo-microspherical ZnO/CdS core-shell structures were fabricated by precipitation method. ZnO pseudo-microspheres of about 2 µm diameter were uniformly synthesized, and they were used as core materials covered with various amounts of CdS shell nanoparticles. The highest hydrogen production rate from as-prepared photocatalysts was 146 μmol g⁻¹ h⁻¹ at 63 wt% CdS content under one sun irradiation condition. After thermal treatments, it was much improved to 241.2 μmol g⁻¹h⁻¹ at the same CdS content possibly due to the increased crystallinity and efficient charge flows with an aid of additional CdO component. Reproducibility of hydrogen production revealed stable mode of operation for three consecutive runs. Therefore, ZnO/CdS/CdO ternary photocatalyst systems provide efficient charge separations and electron flows for improving solar hydrogen production by suppressing electron-hole recombinations.