A ZnO/TiO2 composite nanorods photoanode with improved performance for dye‐sensitized solar cells

A dye‐sensitized solar cell (DSSC) based on ZnO/TiO₂ composite nanorods (NRs) photoanode is fabricated. The power conversion efficiency (PCE) of the ZnO/TiO₂ composite NRs film DSSC is 4.36%, which is obviously higher than that of DSSCs based on pure TiO₂ NRs (0.6%) and ZnO NRs (3.10%). The enhanced performance of ZnO/TiO₂ composite NRs film DSSC can be attributed to the combined effects of ZnO and TiO₂ NRs. In this architecture, the thick ZnO NRs overlayer offers a large surface area for enough dye absorption, while the thin TiO₂ NRs underlayer not only offers a direct and quick pathway for photoinjected electron transfer along the photoanode but also acts as a blocking layer, which effectively hinders the direct contact between the substrate and the electrolyte resulting in lower carrier recombination.     

Tunable synthesis of hierarchical TiO2 spheres consisting of rutile nanowires for dye‐sensitized solar cells and photocatalysis

Hierarchical TiO₂ spheres consisting of rutile nanowires (HTS) are successfully prepared in the bulk solution via a non‐polar solvent/polar solution interfacial syntheses strategy. The effect of reaction temperature on the morphology, size, BET surface area and monodispersion of HTS is studied systematically. Increasing reaction temperature decreases the diameter of spheres in micro‐scale whereas increases the diameter of nanowires in nano‐scale for these HTS. Monodisperse HTS are formed at 230 °C for 20 h, which can suitably be served as light scattering structure for dye‐sensitized solar cell with the additional advantage of rapid electron transport rate. A high efficiency of 8.54% was achieved for the composite DSSC consisting of nanoparticles and monodispersed HTS (synthesized at 230 °C), showing 31.38% improvement compared with that (6.5%) of the DSSCs made from pure P25 nanoparticles at the similar thickness. Furthermore, the photocatalytic performances of HTS for the degradation of methyl orange were also investigated. Contrary to the effect on the performance of DSSC, the HTS synthesized at 150 °C show higher photocatalytic degradation efficiency due to larger BET surface area.     

Studies on the fabrication and characteristics of photoelectrochemical cells using IrO2-coated TiO2 photoanode for Z-scheme water splitting and perovskite solar cell bias

ABSTRACT

In the present work, to build a water splitting system using only a neutral electrolyte solution and light source, we investigated the photoelectrochemical properties and interface resistances of an IrO₂-coated TiO₂ photoanode in Z-scheme configuration. The photoelectrochemical cell was connected to the perovskite solar cell with to realize the system with no need for an external electrical bias. Photoanodes with IrO₂ were found to support hole transport and to reduce the overpotential, therefore increasing the current density of the system consisting of photoelectrochemical cells. A maximum solar-to-hydrogen efficiency of 8.2% was achieved in a neutral electrolyte.