Preparation of nitrogen-doped TiO₂/graphene nanohybrids and application as counter electrode for dye-sensitized solar cells

The preparation of nitrogen-doped TiO₂/graphene nanohybrids and their application as counter electrode for dye-sensitized solar cell (DSSC) are presented. These nanohybrids are prepared by self-assembly of pyrene modified H₂Ti₃O₇ nanosheets and graphene in aqueous medium via π-π stacking interactions, followed by thermal calcination at different temperatures in ammonia atmosphere to afford nitrogen-doped TiO ₂/graphene nanohybrids. H₂Ti₃O₇ nanosheets were synthesized from TiOSO₄·xH₂O by a hydrothermal reaction at 150 C for 48 h. The microstructure of the obtained mixed-phase nanohybrids was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transforms infrared spectroscopy (FTIR). Moreover, the performances of the as-prepared nanohybrids as counter electrode materials for DSSC was investigated, and the results indicated that the nanohybrids prepared at higher nitridation temperature would lead to higher short-circuit current density than those prepared at lower nitridation temperature, indicating that it can be utilized as a low-cost alternative to Pt for DSSCs and other applications.