Ordered Single-Crystalline Anatase TiO2 Nanorod Clusters Planted on Graphene for Fast Charge Transfer in Photoelectrochemical Solar Cells

Achieving efficient charge transport is a great challenge in nanostructured TiO2-electrode-based photoelectrochemical cells. Inspired by excellent directional charge transport and the well-known electroconductibility of 1D anatase TiO2 nanostructured materials and graphene, respectively, planting ordered, single-crystalline anatase TiO2 nanorod clusters on graphene sheets (rGO/ATRCs) via a facial one-pot solvothermal method is reported. The hierarchical rGO/ATRCs nanostructure can serve as an efficient light-harvesting electrode for dye-sensitized solar cells. In addition, the obtained high-crystallinity anatase TiO2 nanorods in rGO/ATRCs possess a lower density of trap states, thus facilitating diffusion-driven charge transport and suppressing electron recombination. Moreover, the novel architecture significantly enhances the trap-free charge diffusion coefficient, which contributes to superior electron mobility properties. By virtue of more efficient charge transport and higher energy conversion efficiency, the rGO/ATRCs developed in this work show significant advantages over conventional rGO-TiO2 nanoparticle counterparts in photoelectrochemical cells.