An ultrafine hyperbranched CdS/TiO2 nanolawn photoanode with highly efficient photoelectrochemical performance

The microstructure of semiconductor materials is of vital importance to its photoelectrochemical performance because the well-optimized special architecture offers rapid electron transport pathways for the photogenerated electrons and provides large areas for light harvesting. In the present paper, an ultrafine hyperbranched TiO2 nanolawn (TiO2 UFHBNL) photoanode was prepared through a facile one-step solvothermal method under employing a suitable dosage of H2O and diethylene glycol (DEG). Along with varying the dosages of H2O and DEG in the solvothermal process, both the crystal structure and morphology of the prepared TiO2 nanosubstrate changed gradually. With the increase of the dosage of H2O and DEG from 5 mL: 35 mL-10 mL: 30 mL and further to 20 mL: 20 mL, the crystal phase of the TiO2 nanosubstrate transforms from amorphous state to anatase phase and eventually to anatase-rutile mixed phases. And, the morphology of TiO2 nanosubstrate changes from thick nanotrees to UFHBNL architecture and then to nanoparticles. The TiO2 UFHBNL photoanode with the ultrafine hyperbranched architecture (diameter of 5-10 nm) after the CdS nanoparticles (5 nm) decoration shows an extremely enhanced photoelectrochemical performance. The ultrafine hyperbranched TiO2 substrate also induces the super-refinement of the deposited CdS nanoparticles (5 nm) on the sub-branches. A maximum photocurrent density of 5.6 and 3.8 mA cm(-2) are obtained under AM1.5 light and visible light illumination, respectively. The highly efficient photoelectrochemical performance is attributed to the decreased charge transfer barrier which contributes to fast charge transport and decreased recombination efficiency of the carriers. This strategy is beneficial for designing the high-performance photoanodes with the ultrafine hyperbranched architecture. (C) 2019 Elsevier B.V. All rights reserved.