Site-selective doping induced synergistic effect of midgap states and aspect ratio-related charge transfer in Ag2S-ZnS heterostructure toward H2 photoproduction

Ag 2 S-ZnS (AZ) heterostructures with tunable aspect ratio (AR) and band structure were successfully synthesized by site-selective doping of metal ions. TEM and XPS results showed that by doping Cu, Mn and Cd ions in AZ heterostructures (Cu: AZ, Mn: AZ and Cd: AZ), respectively, the morphology of AZ heterostructures changed from tadpole-shape (Cu: AZ with AR of 1.2) to matchstick-shape (Cd: AZ with AR of 3.9) due to the selective doping of Cu ions in Ag 2 S head and Cd ions in ZnS tail as well as the doping of Mn ions both in Ag 2 S head and ZnS tail (Mn: AZ with AR of 2.7). All the UV-Vis spectra of doped AZ showed Urbach tail absorption, suggesting the existence of midgap-states created by metal ion dopants , which was confirmed by PL results. Cd: AZ with the largest AR values and Cd-doping induced midgap states showed the highest photocatalytic H 2 -production rate of 1443.55 μmol h −1 g −1 . The catalytic activity of the Cd: AZ can be ascribed to the synergistic effect of midgap states and aspect ratio-dependent charge transfer, which all originate from the site-selective doping of metal ions. This investigation demonstrates a facile way to manipulate the charge carrier dynamics of semiconductor heterostructures by synergistic effects through simultaneously tuning and optimizing the electronic and morphological structures.