Enhanced photocatalytic activity of multifunctional graphene quantum dots decorated TiO₂ film for dye-sensitized solar cells

Graphene quantum dots, as one of the pioneering materials applied in energy storage devices, possess outstanding electrical, optical, thermal, and mechanical properties. Concerning the commercial application of dye-sensitized solar cells, it is imperative to seek materials with highly effective photocatalytic activity. Herein, a novel carbon-based material based on graphene quantum dot nanorods has been prepared via hydrothermal treatment in addition to the syntheses of graphene quantum dots (GQDs) with sizes of approximately 5 and 20 nm. Efficient photoelectrodes are fabricated based on graphene quantum dot nanorods (GQDs-NRs) decorated TiO₂ and their use in dye-sensitized solar cells (DSSCs) is successfully demonstrated with the maximum short circuit current density of 18.20 ± 0.02 mA cm⁻² and an efficiency of 8.06 ± 0.01%, which are remarkably greater than even traditional DSSCs (without GQDs). Hence, incorporating GQDs-NRs and GQDs with controllable size not only enhances dye-sensitized solar cell properties but also decreases the amount of dye or colorant required, which is significant for cost reduction and environmental protection. Thus, the present work provides a practical approach for configuring the size of GQDs-NRs and original GQDs for their onward utilization in TiO₂-coated electrodes. The synthesized material shows high photocatalytic activity, making it suitable for efficient and cost-effective energy transformation devices.