Synthesis of ZnO core/shell hollow microspheres to boost light harvesting capability in quantum dots-sensitized solar cell

Core-shell ZnO@TiO2 hexagonal prism heterogeneous structures as photoanodes for boosting the efficiency of quantum dot sensitized solar cells

In quantum dot sensitized solar cells (QDSSCs), the photoanode provides a stable support for the quantum dots, and promotes the production of photogenerated electrons and the transfer to external circuit. Therefore, it is very important to search for excellent photoanodes for the commercial application of QDSSCs. In this paper, a core-shell ZnO@TiO2 hexagonal prism heterogeneous structure was prepared by a two-step hydrothermal method. The ZnO@TiO2 heterogeneous structure not only has a unique 1D hexagonal prism morphology, but also can effectively inhibit the electron-hole recombination and has a greater light response and higher collection efficiency while speeding up the electron transmission rate. By adjusting the concentration of the TiO2 source, the best photoanode material Zn@Ti-2 was explored, and it showed excellent cell performance: Jsc = 25.4 mA cm-2, Voc = 0.71 V, PCE = 8.5%, and FF = 0.49. Compared with a single ZnO photoanode, the PCE value is increased by 25%. EIS, Tafel polarization and transient photocurrent responses confirm that the Zn@Ti-2 photoanode has higher catalytic activity and stability. Therefore, Zn@Ti-2 may be a promising photoanode material for QDSSCs.

Photocatalytic Degradation of Rhodamine B Dye in Aqueous Suspension by ZnO and M-ZnO (M = La3+, Ce3+, Pr3+ and Nd3+) Nanoparticles in the Presence of UV/H2O2

In this study, nanoparticles of five photocatalytic systems based on pure zinc oxide and with rare earths ions M-ZnO (M = La3+, Ce3+, Pr3+ or Nd3+) calcined at 500 °C or 700 °C were synthesized and investigated as potential photocatalysts for the removal of dyes. The addition of rare earth ions causes a decrease in the bandgap of ZnO; therefore, it can be well used to improve the photocatalytic properties. The photocatalytic activity of the synthesized nanoparticles was evaluated by the degradation of Rhodamine B in the presence of H2O2 under ultraviolet illumination. The results indicate that all the synthesized nanoparticles show good dye degradation efficiency. The highest degradation efficiency was 97.72% for the Ce-ZnO sample calcined at 500 °C and was achieved in 90 min with an excellent constant of the dye degradation rate k = 0.0363 min−1 following a first-order kinetic mechanism. The presence of oxychlorides as secondary phases inhibits the rate of the photocatalytic reaction.