Remarkable Enhancement in the Photoelectric Performance of Uniform Flower-like Mesoporous Fe3O4 Wrapped in Nitrogen-Doped Graphene Networks.

The porous structure and excellent specific surface area are superior for use as a counter electrode (CE) material. In addition, N-doped graphene possesses a remarkable electron-transfer pathway and many active sites. Therefore, a novel idea is to wrap uniform flower-like mesoporous Fe3O4 (Fe3O4UFM) in an N-doped graphene (N-RGO) network structure to enhance the power conversion efficiency (PCE). The hybrid materials of Fe3O4UFM@N-RGO are first used as a CE in dye-sensitized solar cells (DSSCs), showing a preeminent conductive interconnected 3D porous structure with more catalytic activity sites and a better ability for and a faster reaction rate of charge transfer, resulting in quicker reduction of I3- than Pt. A 9.26% photoelectric conversion efficiency has been achieved for the DSSCs with Fe3O4UFM@N-RGO as the CE, which is beyond the value of Pt (7.72%). The positive synergetic effect between Fe3O4 and N-RGO is mainly responsible for the remarkable photoelectric property enhancement of this uniform flower-like mesoporous Fe3O4 wrapped in N-doped graphene networks, as demonstrated by the Tafel polarization, electrochemical impedance spectra, and CV curves. These methods will provide a simple way to effectively reproduce CE materials.